# Patent

## Title
Method for producing 3-acetylamino-4-hydroxybenzoic acid

## Abstract

The present invention provides a method for conveniently and efficiently producing a 3-acetylamino-4-hydroxybenzoic acid-type compound that is a stable compound by a process using a microorganism. Specifically the present invention provides a microorganism having an ability to produce 3-amino-4-hydroxybenzoic acid, that is modified so as to increase an activity to form 3-amino-4-hydroxybenzoic acid from dihydroxyacetone phosphate and aspartate semialdehyde, wherein the microorganism is modified so as to increase an N-hydroxyarylamine O-acetyltransferase (NhoA) activity, as well as a method for producing the 3-acetylamino-4-hydroxybenzoic acid-type compound using such a microorganism.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of, and claims priority under 35 U.S.C. §120 to, International Patent Application No. PCT/JP2013/056025, filed on Mar. 5, 2013, which claims priority therethrough under 35 U.S.C. §119 to Japanese Patent Application No. 2012-122388, filed on May 29, 2012, which are incorporated in their entireties by reference. Also, the Sequence Listing filed electronically herewith is hereby incorporated by reference (File name: 2014-11-19T_US-526_Seq_List; File size: 67 KB; Date recorded: Nov. 19, 2014).


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for producing 3-acetylamino-4-hydroxybenzoic acid, and the like.
2. Brief Description of the Related Art
Amino-hydroxybenzoic acid-type compounds are useful as intermediates of dyes, agricultural chemicals, pharmaceuticals, and other organic synthesized products and as a monomer for polymer polybenzoxazole with high performance and heat resistance. 3-Amino-4-hydroxybenzoic acid (3,4-AHBA) is biosynthesized in two steps by both GriI and GriH. GriI catalyzes a carbon-carbon binding reaction between a C4 compound having an amino group and a C3 or C4 compound and GriH catalyzes cyclization of a C7 compound or cyclization of a C8 compound with decarboxylation using dihydroxyacetone phosphate (DHAP) and aspartate semialdehyde (ASA) as substrates.




3,4-AHBA is unstable, and easily oxidized to form 2-aminophenoxazin-3-one-8-carboxylic acid (APOC) (see below). JP 2004-283163-A describes that when 3,4-AHBA forms as a byproduct, it is converted into APOC over time in the culture medium during production of 3-acetylamino-4-hydroxybenzoic acid (3,4-AcAHBA). However, 3,4-AcAHBA is more stable than 3,4-AHBA because 3,4-AcAHBA is stabilized by acetylation and hence avoids oxidation. 3,4-AcAHBA can easily be converted into 3,4-AHBA by treating with an acid, a base or the like. 3,4-AcAHBA can be handled more easily than 3,4-AHBA that is oxidized to form APOC and thus is unstable. Therefore, development of an excellent method for producing 3,4-AcAHBA is desirable.




JP 2004-283163-A describes that when 3,4-AHBA forms as a byproduct, it is converted into APOC over time in the culture medium during production of 3,4-AcAHBA. JP 2004-283163-A also discloses that 3,4-AcAHBA is deacetylated to form 3,4-AHBA.
International Publication WO2010/005099 discloses that 3,4-AHBA is formed by using Corynebacterium glutamicum that has been transformed with griI and griH.
J. Biol. Chem. 281 (2006), 36944-36951 discloses that 3,4-AHBA and 3,4-AcAHBA are formed by introducing griI and griH into Escherichia coli. 
J. Bacteriol. 189 (2007), 2155-2159 discloses that 3,4-AcAHBA is not formed in culture by deleting arylamine N-acetyltransferase (natA) gene in Streptomyces griseus. 
Biochim. Biophys. Acta. 1475 (2000), 10-16 discloses that N-hydroxyarylamine O-acetyltransferase (nhoA) gene derived from Escherichia coli works to catalyze acetylation for an aromatic amino group. Meanwhile, J. Antibiot., vol. 59 (2006), p. 464 discloses that E. coli BAP1 strain forms an N-acetylated product (3,5-AcAHBA) as a byproduct of 3,5-AHBA (a structural isomer of 3,4-AHBA), and also discloses that it is conceivable that NhoA is not a major factor for N-acetylation of 3,5-AHBA because 3,4-AcAHBA is also formed as a byproduct in an NhoA gene-deleted strain (MAR1 strain) of E. coli BAP1.
SUMMARY OF INVENTION
It is an aspect of disclosed subject matter to provide a method for conveniently and efficiently producing a stable 3-acetylamino-4-hydroxybenzoic acid-type compound by a process using a microorganism.
It has been found that nhoA is involved in production of 3,4-AcAHBA as a byproduct from 3,4-AHBA in Escherichia coli. Also, AcAHBA can be formed without production of the byproduct AHBA by the use of a microorganism modified so as to increase an NhoA activity, and the like.
It is an aspect of the disclosed subject matter to provide a microorganism that is able to produce 3-amino-4-hydroxybenzoic acid, wherein said microorganism is modified so as to increase formation of 3-amino-4-hydroxybenzoic acid from dihydroxyacetone phosphate and aspartate semialdehyde, wherein the microorganism is modified so as to increase an N-hydroxyarylamine O-acetyltransferase (NhoA) activity.
It is a further aspect of the disclosed subject matter to provide the microorganism as described above, wherein NhoA is increased by transformation with a recombinant vector comprising a DNA encoding the NhoA.
It is a further aspect of the disclosed subject matter to provide the microorganism as described above, wherein the NhoA is a protein selected from the group consisting of:
(I) a protein comprising the amino acid sequence of SEQ ID NO:2;
(II) a protein comprising an amino acid sequence having one or several amino acid substitutions, deletions, insertions or additions in the amino acid sequence of SEQ ID NO:2 and having an N-hydroxyarylamine O-acetyltransferase activity; and
(III) protein comprising an amino acid sequence having 70% or more identity to the amino acid sequence of SEQ ID NO:2 and having an N-hydroxyarylamine O-acetyltransferase activity.
It is a further aspect of the disclosed subject matter to provide the microorganism as described above, wherein the DNA encoding the NhoA is selected from the group consisting of:
(i) a DNA comprising the nucleotide sequence of SEQ ID NO:3;
(ii) a DNA that hybridizes under a stringent condition with the nucleotide sequence complementary to the nucleotide sequence of SEQ ID NO:3 and encodes a protein having an N-hydroxyarylamine O-acetyltransferase activity; and
(iii) a DNA comprising a nucleotide sequence having 70% or more identity to the nucleotide sequence of SEQ ID NO:3 and encoding a protein having an N-hydroxyarylamine O-acetyltransferase activity.
It is a further aspect of the disclosed subject matter to provide the microorganism as described above, wherein the microorganism belongs to the genus Escherichia, the genus Pantoea, or the genus Corynebacterium. 
It is a further aspect of the disclosed subject matter to provide the microorganism as described above, wherein the microorganism is Escherichia coli, Pantoea ananatis, or Corynebacterium glutamicum. 
It is a further aspect of the disclosed subject matter to provide the microorganism as described above], wherein 3-amino-4-hydroxybenzoic acid is produced by transformation with a recombinant vector comprising a DNA encoding a protein having an activity to form the 3-amino-4-hydroxybenzoic acid from the dihydroxyacetone phosphate and the aspartate semialdehyde.
It is a further aspect of the disclosed subject matter to provide the microorganism as described above, wherein the proteins having the activity to form 3-amino-4-hydroxybenzoic acid are GriI and GriH.
It is a further aspect of the disclosed subject matter to provide the microorganism as described above, wherein the GriI is selected from the group consisting of:
(A) a protein comprising an amino acid sequence of SEQ ID NO:9 or SEQ ID NO:18;
(B) a protein comprising an amino acid sequence having one or several amino acid substitutions, deletions, insertions or additions in the amino acid sequence in (A) above and having an aldolase activity; and
(C) a protein comprising an amino acid sequence having 70% or more identity to the amino acid sequence in (A) above and having an aldolase activity;
and wherein the GriH protein is selected from the group consisting of:
(D) a protein comprising an amino acid sequence of SEQ ID NO:11 or SEQ ID NO:20;
(E) a protein comprising an amino acid sequence having one or several amino acid substitutions, deletions, insertions or additions in the amino acid sequence in (D) above and having a 3-amino-4-hydroxybenzoic acid synthase activity; and
(F) a protein comprising an amino acid sequence having 70% or more identity to the amino acid sequence in (D) above and having a 3-amino-4-hydroxybenzoic acid synthase activity.
It is a further aspect of the disclosed subject matter to provide the microorganism as described above, wherein the DNA encoding the protein having the activity to form 3-amino-4-hydroxybenzoic acid is selected from the group consisting of:
(a) a DNA comprising a nucleotide sequence of SEQ ID NO:10 or SEQ ID NO:19;
(b) a DNA that hybridizes under a stringent condition with a nucleotide sequence complementary to the nucleotide sequence in (a) above and encodes a protein having an aldolase activity;
(c) a DNA that has 70% or more identity to the nucleotide sequence in (a) above and encodes a protein having an aldolase activity;
and wherein the griH gene is a DNA selected from the group consisting of:
(d) a DNA comprising a nucleotide sequence of SEQ ID NO:12 or SEQ ID NO:21;
(e) a DNA that hybridizes under a stringent condition with a nucleotide sequence complementary to the nucleotide sequence in (d) above and encodes a protein having a 3-amino-4-hydroxybenzoic acid synthase activity; and
(f) a DNA that has 70% or more identity to the nucleotide sequence in (d) above and encodes a protein having a 3-amino-4-hydroxybenzoic acid synthase activity.
It is another aspect of the disclosed subject matter to provide a method for producing a 3-acetylamino-4-hydroxybenzoic acid-type compound, comprising culturing the microorganism as described above to form the 3-acetylamino-4-hydroxybenzoic acid-type compound.
It is a further aspect of the disclosed subject matter to provide the method for producing a 3-amino-4-hydroxybenzoic acid-type compound, comprising:
(1) forming a 3-acetylamino-4-hydroxybenzoic acid-type compound as described above; and
(2) deacetylating the 3-acetylamino-4-hydroxybenzoic acid-type compound to form the 3-amino-4-hydroxybenzoic acid-type compound.
It is a further aspect to provide a method for producing a polymer containing a 3-amino-4-hydroxybenzoic acid-type compound as a component, comprising:
(1′) forming the 3-amino-4-hydroxybenzoic acid-type compound as described above; and
(2′) polymerizing the 3-amino-4-hydroxybenzoic acid-type compound to obtain a polymer containing the 3-amino-4-hydroxybenzoic acid-type compound as a component.
It is a further aspect to provide the method as described above, wherein the polymer is a polybenzoxazole polymer.
According to the described subject matter, it is possible to conveniently and efficiently produce a stable 3-acetylamino-4-hydroxybenzoic acid-type compound.



BRIEF DESCRIPTION OF DRAWINGS
FIG. 1(a)-(c) show analysis results of (a) culture supernatant of Escherichia coli BW25113/pSTV28-EcGri/pUC19 strain, (b) culture supernatant of Escherichia coli BW25113/pSTV28-EcGri/pUC19-NhoA strain, and (c) a 3,4-AHBA standard product, by reverse phase column chromatography.



DETAILED DESCRIPTION
The presently disclosed subject matter provides a microorganism having an ability to produce 3-acetylamino-4-hydroxybenzoic acid. When the microorganism is used, the formation of 3-acetylamino-4-hydroxybenzoic acid (3,4-AcAHBA) is facilitated, and accumulation of the non-acetylated product 3-amino-4-hydroxybenzoic acid (3,4-AHBA) can be suppressed in culture medium.
<1> Modification to Increase Activity of N-Hydroxyarylamine O-Acetyltransferase (NhoA)
The production of 3,4-AcAHBA can be facilitated by modifying a microorganism so as to increase the activity of N-hydroxyarylamine O-acetyltransferase (NhoA), and consequently accumulation of 3,4-AHBA can be suppressed in the culture medium. The NhoA activity is an N-hydroxyarylamine O-acetyltransferase activity, and refers to an activity to form 3-acetylamino-4-hydroxybenzoic acid (3,4-AcAHBA) from 3-amino-4-hydroxybenzoic acid (3,4-AHBA) in relationship with 3,4-AHBA.
“Modified so as to increase an NhoA activity” can mean that the NhoA activity becomes higher than the specific activity of an unmodified strain, e.g., a wild-type strain of the microorganism. The NhoA activity can be increased to 150% or more per microbial cell, 180% or more, or 200% or more per microbial cell, as compared with that of the unmodified strain. The microorganism as described herein has only to have more increased NhoA activity than the wild-type strain or the unmodified strain, but it is more desirable that the accumulation of 3,4-AcAHBA in the microorganism is enhanced compared with these strains. “Modified so as to increase an NhoA activity” can also corresponds to when a molecular number of NhoA per cell increases or when the NhoA activity per molecule increases, among others. Specifically, the modification to increase the NhoA activity may be introduced by ordinary mutagenesis or gene engineering treatment. Examples of the mutagenesis include X ray and ultraviolet ray irradiations, and treatments with mutagenic agents such as N-methyl-N′-nitro-N-nitrosoguanidine. Examples of such modification may include introduction of a mutation into a nhoA gene (including an expression regulating region) on a chromosome so that the NhoA activity can be increased compared with that of non-mutant strains. Such modification can be accomplished by transforming a desired microorganism with a recombinant vector including a DNA that encodes a protein having the NhoA activity.
The activity and the degree of an increase of the activity in a target enzyme can be confirmed by measuring the enzyme activity using a cell extract obtained from a candidate microbial strain or a purified fraction therefrom, and comparing it with an activity in the wild-type strain or the unmodified strain. For example, the NhoA activity can be measured by a method described in Biochim. Biophys. Acta. 1475 (2000), 10-16.
A microorganism modified so as to increase the NhoA activity can include a microorganism inherently able to produce 3,4-AHBA, and/or a microorganism to which the ability to produce 3,4-AHBA has been imparted. The ability to produce 3,4-AHBA can be imparted by methods described later. Examples of the microorganism may include, but are not limited to, bacteria, actinomycetes and fungi. The microorganisms can be bacteria belonging to the genus Escherichia, bacteria belonging to the genus Pantoea, or coryneform bacteria.
The bacteria belonging to the genus Escherichia that can be used include strains described in, for example, Neidhardt et al. (Neidhardt, F. C. Ed. 1996. Escherichia coli and Salmonella: Cellular and Molecular Biology/Second Edition pp. 2477-2483. Table 1. American Society for Microbiology Press, Washington, D.C.). Examples of Escherichia coli may include K12 strain (ATCC10798) or its substrains (e.g., BW25113(CGSC7630), DH1 (ATCC33747), MG1655 (ATCC700926), W3110(ATCC27325)), B strain or its substrains (e.g., BL21 (ATCC BAA-1025), REL606 (CGSC12149)) or the like. Those having a CGSC number in the above bacterial strains are available from The Coli Genetic Stock Center (cgsc.biology.yale.edu). Those having an ATCC number in the above bacterial strains are available from American Type Culture Collection (atcc.org).
Bacteria belonging to the genus Pantoea can mean bacteria classified into the genus Pantoea by professionals in microbiology. Some species of Enterobacter agglomerans have been recently reclassified into Pantoea agglomerans, Pantoea ananatis, Pantoea stewartii, and the like, based on analysis of nucleotide sequences of 16S rRNA and the like (Int. J. Syst. Bacteriol. 1993. 43: 162-173). In the present invention, the bacteria belonging to the genus Pantoea also include such bacteria reclassified into the genus Pantoea. Representative bacterial strains in the genus Pantoea may include Pantoea ananatis, Pantoea stewartii, Pantoea agglomerans, and Pantoea citrea. Specific examples thereof may include Pantoea ananatis AJ13355 strain (FERM BP-6614) (Europe Patent Application Publication No. 0952221), Pantoea ananatis AJ13356 strain (FERM BP-6615) (Europe Patent Application Publication No. 0952221), and the like. These bacterial strains are described as bacteria belonging to Enterobacter agglomerans in Europe Patent Application Publication No. 0952221, but have been currently reclassified into Pantoea ananatis based on the analysis of the nucleotide sequences of 16S rRNA and the like as described above.
The group of coryneform bacteria includes bacteria that were conventionally classified into the genus Brevibacterium but have been currently integrated into the genus Corynebacterium (Int. J. Syst. Bacteriol., 41, 255(1991)), also includes bacteria belonging to the genus Brevibacterium that are closely related to bacteria belonging to the genus Corynebacterium, and following are specifically exemplified (International Publication WO2010/005099):
Corynebacterium acetoacidphilum, 
Corynebacterium acetoglutamicum, 
Corynebacterium alkanolyticum, 
Corynebacterium callunae, 
Corynebacterium glutamicum, 
Corynebacterium lilium (Corynebacterium glutamicum),
Corynebacterium melassecola, 
Corynebacterium thermoaminogenes, 
Corynebacterium herculis, 
Brevibacterium divaricatum (Corynebacterium glutamicum),
Brevibacterium flavum (Corynebacterium glutamicum),
Brevibacterium immariophilum, 
Brevibacterium lactofermentum (Corynebacterium glutamicum),
Brevibacterium roseum, 
Brevibacterium saccharolyticum, 
Brevibacterium thiogenitalis, 
Brevibacterium album, 
Brevibacterium cerinum, and 
Microbacterium ammoniaphilum. 
NhoA may include a protein having an amino acid sequence having 70% or more, 80% or more, 90% or more, 95% or more, or 98% or 99% or more identity to the amino acid sequence of SEQ ID NO:2 and having the NhoA activity. Also the nhoA gene may include a DNA having a nucleotide sequence having 70% or more, 80% or more, 90% or more, 95% or more, or 98% or 99% or more identity to the nucleotide sequence of SEQ ID NO:3 and encoding the protein having the NhoA activity.
Homology (e.g., identity or similarity) between the amino acid sequences or between the nucleotide sequences can be determined, for example, by using the algorithm BLAST by Karlin and Altschul (Pro. Natl. Acad. Sci. USA, 90, 5873 (1993)) and FASTA by Pearson (Methods Enzymol., 183, 63 (1990)). Programs termed BLASTP and BLASTN were developed based on this algorithm BLAST (see ncbi.nlm.nih.gov). Thus, the homology between the amino acid sequences and between the nucleotide sequences may be calculated using these programs using the default settings. Also, for example, a numerical value obtained by calculating as a percentage using a full length portion of a polypeptide encoded in ORF using software GENETYX Ver. 7.0.9 with a setting of Unit Size to Compare=2, which is available from Genetyx Corporation employing Lipman-Pearson method may be used as the homology between the amino acid sequences. The lowest value in the values derived from these calculations may be employed as the homology between the amino acid sequences and between the nucleotide sequences.
The nucleotide sequence of the nhoA gene can vary depending on the strain of the microorganism. Examples of the protein encoded by the nhoA gene may include proteins having an amino acid sequence having one or several amino acid substitutions, deletions, insertions or additions at one or multiple positions in the amino acid sequence of SEQ ID NO:2 and having the NhoA activity. Here, “several” varies depending on locations of the amino acid residues in a three-dimensional structure of a protein or types of the amino acid residues, but can be 1 to 100, 1 to 50, 1 to 30, most preferably 1 to 20, or 1 to 10 (for example, 1, 2, 3, 4, or 5). Such a substitution, deletion, insertion, addition or the like includes those due to a naturally occurring mutation (mutant or variant) based on individual difference of a microorganism having the nhoA gene.
The above substitution may be a conservative substitution that is a neutral mutation that causes no functional change. The conservative mutation is a mutation in which the substitution occurs mutually between Phe, Trp and Tyr when a site to be substituted is an aromatic amino acid, between Leu, Ile and Val when a site to be substituted is a hydrophobic amino acid, between Gln and Asn when a site to be substituted is a polar amino acid, between Lys, Arg and His when a site to be substituted is a basic amino acid, between Asp and Glu when a site to be substituted is an acidic amino acid, and between Ser and Thr when a site to be substituted is an amino acid having a hydroxyl group. More specifically, the conservative substitution may include the substitution from Ala to Ser or Thr, the substitution from Arg to Gln, His or Lys, the substitution from Asn to Glu, Gln, Lys, His or Asp, the substitution from Asp to Asn, Glu or Gln, the substitution from Cys to Ser or Ala, the substitution from Gln to Asn, Glu, Lys, His, Asp or Arg, the substitution from Glu to Gly, Asn, Gln, Lys or Asp, the substitution from Gly to Pro, the substitution from His to Asn, Lys, Gln, Arg or Tyr, the substitution from Ile to Leu, Met, Val or Phe, the substitution from Leu to Ile, Met, Val or Phe, the substitution from Lys to Asn, Glu, Gln, His or Arg, the substitution from Met to Ile, Leu, Val or Phe, the substitution from Phe to Trp, Tyr, Met, Ile or Leu, the substitution from Ser to Thr or Ala, the substitution from Thr to Ser or Ala, the substitution from Trp to Phe or Tyr, the substitution from Tyr to His, Phe or Trp, and the substitution from Val to Met, Ile or Leu.
The nhoA gene may also be a DNA that hybridizes with the nucleotide sequence complementary to the nucleotide sequence of SEQ ID NO:3 under a stringent condition and encodes the protein having the NhoA activity. Here, “stringent condition” can mean when a so-called specific hybrid is formed while a non-specific hybrid is not formed. One example is a condition where polynucleotides having high homology (e.g., identity or similarity), for example, 70% or more, 80% or more, 90% or more, 95% or more, or 98% or more homology hybridize each other while polynucleotides having lower homology than that do not hybridize each other. Specifically, such a condition may include hybridization in 6×SSC (sodium chloride/sodium citrate) at about 45° C. followed by one or two or more washings in 0.2×SSC and 0.1% SDS at 50 to 65° C.
<2> Modification to Increase Activity to Form 3-Amino-4-Hydroxybenzoic Acid from Dihydroxyacetone Phosphate and Aspartate Semialdehyde
A microorganism can be modified so as to increase the activity to form 3-amino-4-hydroxybenzoic acid (3,4-AHBA) from dihydroxyacetone phosphate (DHAP) and aspartate semialdehyde (ASA). Such modification can be accomplished by, for example, transforming a desired microorganism with a recombinant vector including a DNA encoding a protein having the activity to form 3,4-AHBA from DHAP and ASA. The protein having the activity to form 3,4-AHBA from DHAP and ASA is not particularly limited as long as the protein contributes to the formation of 3,4-AHBA from DHAP and ASA, and includes, for example, proteins having an enzyme activity to catalyze formation of a carbon-carbon bond between DHAP and ASA (hereinafter sometimes abbreviated as an “aldolase activity”) and proteins having an enzyme activity to catalyze cyclization of a C7 compound obtained by forming the carbon-carbon bond between DHAP and ASA (hereinafter sometimes abbreviated as a 3-amino-4-hydroxybenzoic acid synthase activity). Hereinafter, both the above activities are sometimes referred to as the ability to biosynthesize 3,4-AHBA.
A gene encoding the protein having the enzyme activity to catalyze the formation of the carbon-carbon bond between DHAP and ASA may include a griI gene or a griI gene homolog (both the griI gene and the griI gene homolog are sometimes simply referred to as the griI gene) derived from Streptomyces griseus. The griI gene homolog can refer to a gene that is derived from another microorganism, exhibits high homology to the above gene derived from Streptomyces griseus, and encodes a protein having the aldolase activity. Such a gene can be found by a BLAST search. Examples thereof may include an nspl gene derived from Streptomyces murayamaensis (SEQ ID NO:18 and 19), fructose-bisphosphate aldolase (Accession no. YP_483282) and Fructose-bisphosphate aldolase (Accession no. YP_481172) derived from Frankia sp., Fructose-bisphosphate aldolase (sanger.ac.uk/cgi-bin/blast/submitblast/s —scabies) derived from Streptomyces scabies, fructose-bisphosphate aldolase (Accession no. Q39NQ9) derived from Burkholderia sp. 383, fructose-bisphosphate aldolase (Accession no. NP_247374) derived from Methanococcus jannaschii, and a dhnA gene (Accession no. NC_000913) derived from Escherichia coli(Journal of Biochemistry vol. 281, NO. 48, pp.36944-36951, supplementary data).
The gene encoding the protein having the enzyme activity to catalyze the cyclization of the C7 compound obtained by forming the carbon-carbon bond between DHAP and ASA may include a griH gene or a griH gene homolog (both the griH gene and the griH gene homolog are sometimes simply referred to as the griH gene) derived from Streptomyces griseus. The griH gene homolog can refer to a gene that is derived from another microorganism, exhibits high homology to the above gene derived from Streptomyces griseus, and encodes a protein having the 3-amino-4-hydrosybenzoic acid synthase activity. Such a gene can be found by BLAST search. Examples thereof may include an nspH gene derived from Streptomyces murayamaensis (SEQ ID NO:20 and 21), 3-dehydroquinate synthase (Accession no. YP_483283) and 3-dehydroquinate synthase (Accession no. YP_481171) derived from Frankia sp., 3-dehydroquinate synthase (Accession no.YP—366552) and 3-dehydroquinate synthase (Accession no. YP_366553) derived from Burkholderia sp. 383, 3-dehydroquinate synthase (sanger.ac.uk/cgi-bin/blast/submitblast/s_scabies) derived from
Streptomyces scabies, and 3-dehydroquinate synthase (Accession no. NP_248244) derived from Methanococcus jannaschii (Journal of Biochemistry vol. 281, NO. 48, pp.36944-36951, supplementary data).
GriI and GriH or the griI gene and the griH gene derived from any organism can be used. For example, they can be derived from microorganisms such as the bacteria or actinomycetes described above. Examples of actinomycetes can include microorganisms belonging to the genus Streptomyces. Examples of the microorganisms belonging to the genus Streptomyces can include Streptomyces griseus, Streptomyces murayamaensis, Streptomyces lividans, and Streptomyces scabies. GriI and GriH or the griI gene and the griH gene can be derived from the same microorganism or different microorganisms.
A GriI homolog can have an amino acid sequence having 70% or more, 80% or more, 90% or more, 95% or more, 98% or 99% or more identity to SEQ ID NO:9 or 18 that is an amino acid sequence of a protein encoded by the above griI gene and having the aldolase activity. Examples thereof may include SEQ ID NOS:9, 11, 13, 15, 17, 19, and 21 in the international Publication WO2010/005099. The griI gene homolog can include a nucleotide sequence having 70% or more, 80% or more, 90% or more, 95% or more, 98% or 99% or more identity to SEQ ID NO:10 or 19, and can encode a protein having aldolase activity. Examples thereof may include SEQ ID NOS:8, 10, 12, 14, 16, 18 and 20 in the international Publication WO2010/005099.
A GriH homolog can have an amino acid sequence having 70% or more, 80% or more, 90% or more, 95% or more, 98% or 99% or more identity to SEQ ID NO:11 or 20, is encoded by the above griH gene, and has 3-amino-4-hydroxybenzoic acid synthase activity. Examples thereof may include SEQ ID NOS:23, 25, 27, 29, 31, 33, and 35 in the international Publication WO2010/005099. Also, the griH gene homolog can have a nucleotide sequence having 70% or more, 80% or more, 90% or more, 95% or more, 98% or 99% or more identity to SEQ ID NO:12 or 21, and can encode a protein having 3-amino-4-hydroxybenzoiic acid synthase activity. Examples thereof may include SEQ ID NOS:22, 24, 26, 28, 30, 32, and 34 in the international Publication WO2010/005099.
A position or positions of an amino acid residue, when mutated, which do not influence activity in an amino acid sequence is evident to those of ordinary skill in the art, and a protein mutant may be made further with reference to a sequence alignment. Specifically, those skilled in the art can (1) compare amino acid sequences of a plurality of homolog proteins, (2) determine relatively conserved region(s) and relatively non-conserved region(s), then (3) predict region(s) capable of playing an important role for its function and region(s) incapable of playing an important role for its function from the relatively conserved region(s) and the relatively non-conserved region(s), respectively, and thus recognize correlativity of its structure/function. The international Publication WO2010/005099 discloses the alignment of the amino acid sequences of the above griI gene homologs (FIGS. 1 and 2 in International Publication WO2010/005099), the alignment of the amino acid sequences of the above griH gene homologs (FIGS. 3 and 4 in International Publication WO2010/005099), and their consensus (common) sequences (SEQ ID NOS:36 and 37 in International Publication WO2010/005099). The homologs of the griI gene include a gene encoding the amino acid sequence of SEQ ID NO:36 in International Publication WO2010/005099, and the homologs of the griH gene include a gene encoding the amino acid sequence of SEQ ID NO:37 in International Publication WO2010/005099).
The homology (e.g., identity or similarity) between the amino acid sequences and between the nucleotide sequences can be determined as described above.
The nucleotide sequence of the griI gene or the griH gene may vary depending on species and microbial strain of the microorganism. Thus, it is only necessary that the griI gene and the griH gene be able to enhance the ability to produce 3,4-AHBA in Escherichia coli by expressing them in Escherichia coli, e.g., augmenting their expression. For example, a protein encoded by the griI gene can have an amino acid sequence having one or several amino acid substitutions, deletions, insertions, additions or the like at one or multiple positions in the amino acid sequence of the protein encoded by the griI gene (SEQ ID NO:9 or 18) and have aldolase activity. Examples thereof may include SEQ ID NOS:9, 11, 13, 15, 17, 19, and 21 in the international Publication WO2010/005099. A protein encoded by the griI gene can have an amino acid sequence having one or several amino acid substitutions, deletions, insertions additions or the like at one or multiple positions in the amino acid sequence of the protein encoded by the griH gene (for example, SEQ ID NO:11 or 20) and have 3-amino-4-hydroxybenzoic acid synthase activity. Examples thereof may include SEQ ID NOS:23, 25, 27, 29. 31, 33, and 35 in the international Publication WO2010/005099. Here, “several” varies depending on locations of the amino acid residues in a three-dimensional structure of a protein or types of the amino acid residues, but can be 1 to 50, 1 to 20, 1 to 10 and 1 to 5. Such an amino acid substitution, deletion, insertion, addition or the like can include those that naturally occur (mutant or variant) based on individual difference or species difference of the microorganism having the griI gene or the griH gene, or the like. The substitution can be a conservative substitution that is neutral substitution in which a function is not changed. The conservative substitution is as described above.
Furthermore, degeneracy of the griI gene and the griH gene varies depending on a host to which such a gene is introduced. Thus, codons may be replaced with codons available in a desired microorganism. Likewise, the griI gene and the griH gene may be genes encoding proteins that are extended or truncated on an N terminal side and/or a C terminal side as long as the gene has a function to enhance the ability to produce 3,4-AHBA in a microorganism. For example, a length of extended or truncated residues is 50 or less, 20 or less, 10 or less, or 5 or less of amino acid residues. More specifically, the gene may be a gene encoding a protein in which 50 to 5 amino acid residues on the N terminal side or 50 to 5 amino acid residues on the C terminal side have been extended or truncated.
Such a gene that is homologous to the griI gene or the griH gene can be acquired by, for example, modifying the gene encoding an amino acid sequence by site-specific mutagenesis so that an amino acid residue at a particular position of the encoded protein can include the substitution, deletion, insertion or addition. Such a homologous gene can also be acquired by conventionally known mutation treatments, such as by treating the griI gene or the griH gene with hydroxylamine and the like in vitro or treating a microorganism carrying the gene with ultraviolet ray or a mutating agent such as N-methyl-N′-nitro-N-nitrosoguanidine (NTG) or ethyl methanesulfonate (EMS) generally used for the mutation treatment, error prone PCR (Cadwell, R. C. PCR Meth. Appl. 2, 28(1992)), DNA shuffling (Stemmer, W. P. Nature 370, 389 (1994)), and StEP-PCR (Zhao, H. Nature Biotechnol. 16, 258 (1998)). Utilizing these treatments, a mutation can be artificially introduced into the griI gene or the griH gene by gene recombination to acquire a gene encoding an enzyme with high activity.
The griI gene can also be a DNA that hybridizes under a stringent condition with a nucleotide sequence complementary to a nucleotide sequence of the griI gene or its homolog gene (e.g., SEQ ID NO:10 or 19, or SEQ IDS NO:8, 10, 12, 14, 16, 18 or 20 in the international Publication WO2010/005099) and encodes a protein having the aldolase activity. The griH gene can also be a DNA that hybridizes under a stringent condition with a nucleotide sequence complementary to a nucleotide sequence of the griH gene or its homolog gene (e.g., SEQ ID NO:12 or 21, or SEQ ID NOS:22, 24, 26, 28, 30, 32 or 34 in the international Publication WO2010/005099) and encodes a protein having the 3-amino-4-hydroxybenzoic acid synthase activity. The “stringent condition” is the same as described above.
The descriptions concerning the above gene homologs and the conservative substitution can be applied to the other genes described herein in the same manner.
Whether these griI gene and griH gene and the homolog genes thereof encode or do not encode the protein that enhances the ability to produce 3,4-AHBA can be confirmed by introducing these genes into a bacterium and the like having a gene encoding mutated aspartokinase in which feedback inhibition is canceled, and examining whether the activity of forming 3,4-AHBA is enhanced or not. In such a case, the effect can be verified more clearly by quantifying 3,4-AHBA using reverse phase chromatography according to, for example, Suzuki, et al.'s method [J. Bio. Chem., 281, 823-833 (2006)].
<3> Recombinant Vector
A recombinant vector that can be used can be obtained by introducing a desired gene into an expression vector. For example, when using nhoA, griI, and griH are used together, they may be each carried on a separate recombinant vector for transformation, or they may be linked via an appropriate spacer and carried on the same recombinant vector, as long as they can be expressed. The griI gene and the griH gene may be derived from the same microorganism or different microorganisms. When the griI gene and the griH gene are derived from the same microorganism and located in close proximity on a chromosome, a DNA fragment including both griI and griH may be cut out and carried on a vector.
The recombinant vector generally has a promoter, the aforementioned DNA, e.g., nhoA, griI and griH, and regulatory regions (operator and terminator) necessary for expression of the genes in the recombinant microorganism at appropriate positions so that they can function.
An expression vector that can be used as a recombinant vector is not particularly limited, as long as it can function in the chosen microorganism, and can be a plasmid that autonomously replicates out of a chromosome or can be integrated into the chromosome in a bacterium. Specifically, examples of the expression vector may include pBR322, pHSG299, pHSG298, pHSG399, pHSG398, pSTV28, pSTV29 (pHSG and pSTV are available from Takara Bio Inc.), pMW119, pMW118, pMW219, MW218 (pMW series are available from Nippon Gene Co., Ltd.), and the like, which are plasmids capable of autonomously replicating in bacteria belonging to enteric bacteria groups when introduced into a bacterium belonging to the genus Escherichia or Pantoea. A phage DNA may be used as the vector in place of the plasmid. When introduced into a bacterium belonging to the genus Corynebacterium, examples of the expression vector may include pCRY30 (described in JP 3-210184-A), pCRY21, pCRY2KE, pCRY2KX, pCRY31, pCRY3KE and pCRY3KX (described in JP 2-72876-A and U.S. Pat. No. 5,185,262), pCRY2 and pCRY3 (described in JP 1-191686-A), pAM330 (described in JP 58-67679-A), pHM1519 (described in JP 58-77895-A), pAJ655, pAJ611 and pAJ1844 (described in JP 58-192900-A), pCG1 (described in JP 57-134500-A), pCG2 (described in JP 58-35197-A), pCG4 and pCG11 (described in JP 57-183799-A), pVC7 (described in JP 9-070291-A), pVK7 (described in JP 10-215883-A), which are plasmids capable of autonomously replicating in bacteria belonging to the genus Corynebacterium, and derivatives thereof.
The promoter is not particularly limited, and a promoter generally used for production of a foreign protein in a desired microorganism can be used. For example, a T7 promoter, a lac promoter, a trp promoter, a trc promoter, a tac promoter, a PR promoter and PL promoter of a lambda phage, a T5 promoter and the like are known in the use for the genus Escherichia or Pantoea. Strong promoters such as promoters for genes encoding PS 1 and PS2 that are cell surface proteins derived from the genus Corynebacterium (described in JP 6-502548-A) and a promoter for a gene encoding SlpA that is a cell surface protein derived from the genus Corynebacterium (described in JP 10-108675-A) may be included in the use for the genus Corynebacterium. 
<4. Transformant>
The microorganism is not particularly limited as long as it is able to produce 3-amino-4-hydroxybenzoic acid and is modified so as to increase the activity of N-hydroxyarylamine O-acetyltransferase (NhoA), and can be a transformant. The transformant can be obtained by transforming with a recombinant vector that includes a DNA that encodes a protein having an activity to form 3-amino-4-hydroxybenzoic acid from dihydroxyacetone phosphate and aspartate semialdehyde.
A host microorganism can be a microorganism that can efficiently supply dihydroxyacetone phosphate, aspartate semialdehyde, and an acetyl group donor (e.g., acetyl CoA) that are substrates for biosynthesis of 3-acetylamino-4-hydroxybenzoic acid-type compounds. Aspartokinase (AK) in microorganisms is originally subjected to concerted feedback inhibition by an amino acid such as lysine. For example, Escherichia coli has aspartokinase III (AKIII) that is a non-conjugated enzyme and functions alone. AKIII in Escherichia coli is originally subjected to feedback inhibition by lysine. On the other hand, it is known that AK in a coryneform bacterium is a heteroprotein composed of an α-subunit and a β-subunit and coding regions of the α-subunit gene and the β-subunit gene are partially overlapped. AK in a coryneform bacterium is originally subjected to concerted feedback inhibition by lysine and threonine. A microorganism having an AK gene with a mutation that substantially cancels the feedback inhibition can be used.
The mutations capable of canceling the feedback inhibition by an amino acid such as lysine have been reported for aspartokinase derived from various microorganisms such as Escherichia coli, Corynebacterium glutamicum, Serratia marcescens and the like. For example, the mutation of glutamic acid at position 250 to lysine (E250K), the mutation of methionine at position 318 to isoleucine (M318I), the mutation of threonine at position 344 to methionine (T344M), the mutation of serine at position 345 to leucine (S345L), the mutation of threonine at position 352 to isoleucine (T352I) have been reported as the mutation capable of canceling the feedback inhibition by lysine in AKIII from Escherichia coli (see, e.g., Kikuchi et al., FEMS Microbiology Letters 173, 211-215 (1999), and Falco et al., BioTechnology 13, 577-582 (1995)). The mutation capable of canceling the feedback inhibition in AK from a coryneform bacterium is explained by taking an α-subunit of wild-type AK derived from Corynebacterium glutamicum (Brevibacterium lactofermentum) ATCC 13869 (see, e.g., SEQ ID NO:38 in the international Publication WO2010/005099) as an example. Canceling the feedback inhibition in AK is accomplished by substituting the alanine residue at position 279 from the N terminus on the α-subunit with a threonine residue, or substituting the threonine residue at position 311 from the N terminus with an isoleucine residue, or substituting the serine residue at position 301 from the N terminus with a tyrosine residue, or substituting the threonine residue at position 380 from the N terminus with an isoleucine residue, or substituting the threonine residue at position 308 from the N terminus with an isoleucine residue, or substituting the arginine residue at position 320 from the N terminus with a glycine residue, or substituting the glycine residue at position 345 from the N terminus with an aspartic acid (the international Publication WO94/25605, the international Publication WO00/63388, U.S. Pat. No. 6,844,176, International Publication WO01/049854 and the like). The amino acid sequence of AK even derived from the wild type is different in several amino acid residues from the amino acid sequence of SEQ ID NO:38 in the international Publication WO2010/005099, depending on type and strain of the coryneform bacterium from which the AK is derived. AK may be such an allelic variant. The definition of such mutations is the same as that described for aforementioned griI and griH.
The microorganism having the AK gene in which the mutation as described above has been introduced can be used. The amino acid sequence of AK even derived from the wild type is different in several amino acid residues depending on the type and the strain of the coryneform bacterium from which the AK is derived. Such an allelic variant may be used. The position to be modified for canceling the feedback inhibition in the allelic variant can be identified by performing a sequence alignment. The modification for canceling the feedback inhibition in AK can be accomplished by a method publicly known to those skilled in the art, for example, acquisition of a mutant strain having resistance to a lysine analog such as 2-aminoethylcysteine or introduction of site-specific mutagenesis by gene replacement utilizing homologous recombination. Also, a microorganism with an augmented activity of a mutated AK in which the feedback inhibition was canceled can also be obtained by transforming the microorganism with a plasmid that includes a mutated AK gene in which the feedback inhibition was canceled.
The expression of a pyruvate carboxylase gene may further be augmented in the microorganism having the mutated AK gene in which the feedback inhibition was canceled.
According to methods known in the art, the microorganism can be transformed with a recombinant vector that includes a DNA encoding a protein able to form 3-amino-4-hydroxybenzoic acid from dihydroxyacetone phosphate and aspartate semialdehyde. For example, a protoplast method (Gene, 39, 281-286 (1985)), an electroporation method (Bio/Technology, 7, 1067-1070 (1989)), and the like can be used. When transformation for canceling the feedback inhibition in AK is performed, either the transformation for conferring the activity of forming 3,4-AHBA or the transformation for canceling the feedback inhibition in AK may be performed first.
<5> Methods for Producing 3-acetyamino-4-hydroxybenzoic Acid-Type Compound, and Methods for Producing 3-amino-4-hydroxybenzoic Acid-Type Compound and Polymer Comprising 3-amino-4-hydroxybenzoic Acid-Type Compound as Component
<5-1> Methods for Producing 3-acetyamino-4-hydroxybenzoic Acid-Type Compound
A method for producing a 3-acetylamino-4-hydroxybenzoic acid-type compound is described, and includes steps of culturing the microorganism as described herein to form the 3-acetylamino-4-hydroxybenzoic acid-type compound. The 3-acetylamino-4-hydroxybenzoic acid-type compound can be biosynthesized from dihydroxyacetone phosphate, aspartate semialdehyde and an acetyl group donor (e.g., acetyl CoA). Therefore, the microorganism can efficiently supply the dihydroxyacetone phosphate, the aspartate semialdehyde and the acetyl group donor (e.g., acetyl CoA), which are substrates in biosynthesis of the 3-acetylamino-4-hydroxybenzoic acid-type compound. Also, the microorganism may be cultured in a medium containing the dihydroxyacetone phosphate, the aspartate semialdehyde and the acetyl group donor in large amounts.
The 3-acetyamino-4-hydroxybenzoic acid-type compound includes 3-acetyamino-4-hydroxybenzoic acid (hereinafter sometimes abbreviated as “3,4-AcAHBA”) having the following structure as well as a derivative and a salt thereof.




In the derivative of the 3-acetylamino-4-hydroxybenzoic acid-type compound, (1) either the carboxyl group at position 1, the acetylamino group at position 3, and/or the hydroxyl group at position 4, or a combination of these, is/are derivatized, (2) the carboxyl group at position 1, the acetylamino group at position 3, and the hydroxyl group at position 4 are kept and a hydrogen atom on at least one carbon atom at position 2, 5 or 6 is substituted with other atom or group, or (3), (1) and (2) are combined. Examples of the other atom or group in (2) above may include halogen atoms (e.g., a fluorine atom, a bromine atom, a chlorine atom, an iodine atom), alkyl groups (e.g., alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, and hexyl), a hydroxyl group, an alkyloxy group (the alkyl moiety is the same as described above), an amino group, a mono- or di-alkylamino group (the alkyl moiety is the same as described above), a cyano group, a nitro group, a sulfonyl group, and a carboxyl group. Specifically, examples of the derivative in (1) above may include derivatives in which the carboxyl group at position 1 is derivatized (e.g., 3-amino-4-hydroxybenzaldehyde in which the carboxyl group in 3-acetylamino-4-hydroxybenzoic acid is aldehydated), derivatives in which the acetylamino group at position 3 is derivatized with the group such as the above alkyl group (e.g., 3-acetylalkylamino derivatives), and derivatives in which the hydroxyl group at position 4 is derivatized with the group such as the above alkyl group (e.g., 4-alkyloxy derivatives).
Base salts such as alkali metal (e.g., sodium, potassium, lithium) salts and alkali earth metal (e.g., calcium, magnesium) salts of carboxylic acid, and acid addition salts such as hydrochloride salts, sulfate salts, lead nitrate and phosphate salts are exemplified as salts.
The 3-acetylamino-4-hydroxybenzoic acid-type compound can be produced by culturing the microorganism and recovering the 3-acetylamino-4-hydroxybenzoic acid-type compound produced in the medium.
The medium for culturing the microorganism is not particularly limited as long as the desired microorganism is grown, and the microorganism can be cultured according to methods known in the art. For example, the microorganism can be cultured in an ordinary medium containing a carbon source, a nitrogen source, and inorganic ions. Organic trace nutrients such as vitamins and amino acids may be added if necessary in order to obtain higher proliferation. A cultivation temperature is generally 25 to 42° C., and it is desirable to control pH to 5 to 8. A cultivation time period is generally 20 to 90 hours.
It is desirable to perform the cultivation of the microorganism under a condition that controls oxygen supply. Specifically, it is desirable to keep oxygen at 2.0 ppm or less when microbial growth enters the logarithmic growth phase.
A recovery method used in steps of recovering and purifying the 3-acetylamino-4-hydroxybenzoic acid-type compound from the culture medium may be appropriately selected from known methods. For example, recovery can occur from a culture medium supernatant obtained by removing microbial cells by centrifugation or membrane filtration after adjusting pH of the culture medium to an acidic pH at which solubility of the 3-acetylamino-4-hydroxybenzoic acid-type compound is high. The recovery method of 3-acetylamino-4-hydroxybenzoic acid from the culture medium supernatant in which the microbial cells have been removed may include purification by a porous adsorbent, crystallization and precipitation.
The porous adsorbent can be a porous solid adsorbent having a large surface area, and specifically can include hydrophilic adsorbents typified by silica gel, alumina, zeolite, bauxite, magnesia, activated white earth, acrylic synthetic adsorbents, and the like, and hydrophobic adsorbents typified by vegetable charcoal, bone charcoal, activated charcoal and aromatic synthetic adsorbents, and the like. Any adsorbent can be used without particular limitation as long as the purity of the 3-acetylamino-4-hydroxybenzoic acid-type compound can be enhanced by adsorbing the impurities. In this regard, however, the impurities adsorbed by the porous adsorbent abundantly contain aromatic compounds mainly produced in the process of biochemical synthesis. Thus, the hydrophobic adsorbent typified by the activated charcoal and the aromatic synthetic adsorbent to which these compounds easily adsorb can be used. These hydrophobic adsorbents may be used alone or in combination of two or more.
When the activated charcoal is used, its raw material is not particularly limited, and may include, but is not particularly limited to, plant raw materials such as wood powder and palm shell, coal/petroleum-based raw materials such as smokeless coal, petroleum pitch and cokes, synthetic resin-based raw materials such as acrylic resins, phenol resins, epoxy resins and polyester resins. Shapes of the activated charcoal are powder, grain and fibrous, and secondary processed articles such as filters and cartridges, and that easily handled may be appropriately selected.
Meanwhile, when an aromatic synthetic adsorbent is used, the raw material thereof is not particularly limited, and for example, the porous resins such as 1) unsubstituted aromatic resins, 2) aromatic resins having a hydrophobic substituent(s), and 3) aromatic resins obtained by giving a special treatment to the unsubstituted aromatic resins can be used. Specific compounds may include, for example, styrene- and divinylbenzene-based resins.
As mentioned above, an objective of contacting the 3-acetylamino-4-hydroxybenzoic acid-type compound in the culture medium with the porous adsorbent is to adsorb the impurities to the porous adsorbent and to improve the purity of the 3-acetylamino-4-hydroxybenzoic acid-type compound. However, the 3-acetylamino-4-hydroxybenzoic acid-type compound which is an objective product is sometimes adsorbed together in no small part with the impurities to the porous adsorbent. Thus, it is also possible to isolate and recover the 3-acetylamino-4-hydroxybenzoic acid-type compound by contacting the 3-acetylamino-4-hydroxybenzoic acid-type compound in the culture medium to the porous adsorbent, then contacting the porous adsorbent with a polar organic solvent to detach the 3-acetylamino-4-hydroxybenzoic acid-type compound from the porous adsorbent and dissolve the 3-acetylamino-4-hydroxybenzoic acid-type compound in the polar organic solvent. The polar organic solvent can be an organic solvent composed of polar molecules having a high dielectric constant, and can be used without particular limitation as long as the 3-acetylamino-4-hydroxybenzoic acid-type compound can be detached from the porous adsorbent and the 3-acetylamino-4-hydroxybenzoic acid-type compound can be dissolved in the polar organic solvent. The polar organic solvent may be used alone or in combination with two or more at a desired combination ratio.
The crystallization or the precipitation can produce a crystal or a precipitate by evaporating the solvent in which an objective substance is dissolved to concentrate, or lowering the temperature, or keeping the concentration higher than a saturation solubility by adding a poor solvent to the solvent in which an objective substance is dissolved, and is not particularly limited including conventionally and publicly known methods. The produced crystal or precipitate can be separated by precipitation, filtration, centrifugation or the like.
<5-2> Methods for Producing 3-amino-4-hydroxybenzoic Acid-Type Compound
The present invention also provides a method for producing a 3-amino-4-hydroxybenzoic acid-type compound. This method includes the following:
(1) forming a 3-acetylamino-4-hydroxybenzoic acid-type compound by the aforementioned method; and
(2) deacetylating the 3-acetylamino-4-hydroxybenzoic acid-type compound to form the 3-amino-4-hydroxybenzoic acid-type compound.
The 3-amino-4-hydroxybenzoic acid-type compound in the present invention includes 3-amino-4-hydroxybenzoic acid (hereinafter sometimes abbreviated as “3,4-AHBA”) having the following structure as well as a derivative and a salt thereof.




In the derivative of the 3-amino-4-hydroxybenzoic acid-type compound, (1) the carboxyl group at position 1, the amino group at position 3, and/or the hydroxyl group at position 4 is derivatized, (2) the carboxyl group at position 1, the amino group at position 3 and the hydroxyl group at position 4 are kept and a hydrogen atom on at least one carbon atom at positions 2, 5 and 6 is substituted with other atom or group, or (3), (1) and (2) are combined. Examples of the other atom or group in (2) above may include halogen atoms (e.g., a fluorine atom, a bromine atom, a chlorine atom, an iodine atom), alkyl groups (e.g., alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl and the like), a hydroxyl group, an alkyloxy group (the alkyl moiety is the same as described above), an amino group, a mono- or di-alkylamino group (the alkyl moiety is the same as described above), a cyano group, a nitro group, a sulfonyl group, and a carboxyl group. Specifically, examples of the derivative in (1) above may include derivatives in which the carboxyl group at position 1 is derivatized (e.g., 3-amino-4-hydroxybenzaldehyde in which the carboxyl group in 3-amino-4-hydroxybenzoic acid is aldehydated), derivatives in which the amino group at position 3 is derivatized with the group such as the above alkyl group (e.g., 3-alkylamino derivatives), and derivatives in which the hydroxyl group at position 4 is derivatized with the group such as the above alkyl group (e.g., 4-alkyloxy derivatives).
Base salts such as alkali metal (e.g., sodium, potassium, lithium) salts and alkali earth metal (e.g., calcium, magnesium) salts of carboxylic acid, and acid addition salts such as hydrochloride salts, sulfate salts, lead nitrate and phosphate salts are exemplified as salts.
The step (1) in the above method can be carried out in the same manner as in the aforementioned method for producing the 3-acetylamino-4-hydroxybenzoic acid-type compound.
The deacetylation in the step (2) in the above method can be carried out in any method known in the art. For example, the deacetylation can be carried out by hydrolysis utilizing an acid or a base. The acid is not particularly limited as long as a deacetylation reaction of Ac-AHBA-type compounds progresses, and can be a strong acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and the like. The base is not particularly limited as long as the deacetylation reaction of Ac-AHBA-type compounds progresses, and it can be capable of increasing the reactivity of the deacetylation reaction to use a strong base such as sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, and the like. The obtained 3-amino-4-hydroxybenzoic acid-type compound may be recovered and purified. The recovery and the purification of the 3-amino-4-hydroxybenzoic acid-type compound can be carried out in the same manner as in the recovery and the purification of the 3-acetylmino-4-hydroxybenzoic acid-type compound as described above.
<5-3> Methods for Producing Polymer Having 3-amino-4-hydroxybenzoic Acid-Type Compound as Component
The present invention also provides a method for producing a polymer including a 3-amino-4-hydroxybenzoic acid-type compound as a component. This method includes the following:
(1′) forming the 3-amino-4-hydroxybenzoic acid-type compound by the aforementioned method; and
(2′) polymerizing the 3-amino-4-hydroxybenzoic acid-type compound to obtain a polymer containing the 3-amino-4-hydroxybenzoic acid-type compound as a component.
The step (1′) can be carried out in the same manner as in the aforementioned method for producing the 3-amino-4-hydroxybenzoic acid-type compound.
The step (2′) can be carried out in any method known in the art. For example, the 3-amino-4-hydroxybenzoic acid-type compound obtained by the aforementioned method can be polymerized by condensation polymerization in a non-oxidizing solvent acid such as methanesulfonic acid or polyphosphoric acid at high temperature (see, e.g., WO91/01304). In the production method of a polymer according to the present invention, the 3-amino-4-hydroxybenzoic acid-type compound may be polymerized with other constituents of a polymer. Examples of the other constituents include terephthalic acid and bisphenol A, or terephthalic acid and p-phenylenediamine. Polymerizing method can be practiced by utilizing various known methods (U.S. Pat. Nos. 5,142,021, 5,219,981 and 5,422,416, and Kricheldorf et. al., (1992) Makromol. Chem., 193, 2467-2476, and Marcos-Fernandez et. al., (2001) Polymer, 42, 7933-7941). Examples of the polymer that includes a 3-amino-4-hydroxybenzoic acid-type compound as a component which is produced by the method as described herein include polybenzoxazole polymers, polyesters and polyamides.
EXAMPLES
The present invention will be described below with reference to the following non-limiting Examples. Chosen host microorganisms can efficiently supply dihydroxyacetone phosphate, aspartate semialdehyde, and acetyl CoA that is the acetyl group donor, which are substrates in biosynthesis of a 3-acetylamino-4-hydroxybenzoic acid-type compound.
Example 1
Construction of 3,4-AcAHBA-producing bacterium by introducing 3,4-AHBA synthetase gene group derived from Streptomyces griseus and nhoA gene derived from Escherichia coli into Escherichia coli, and evaluation of amount of accumulated 3,4-AcAHBA
(1) Search of Enzyme that Catalyzes N-Acetylation of 3,4-AHBA Based on Genomic Information of Escherichia coli 
It has been reported that arylamine N-acetyltransferase (convertible term: NatA; NCBI accession ID: BAF46971.1) catalyzes an N-acetylation reaction of 3,4-AHBA in Streptomyces griseus IFO13350 strain (Suzuki et. al., (2007) J. Bacteriol., 189, 2155-2159). An amino acid sequence of NatA is shown as SEQ ID NO:1. In order to search an enzyme having the same function as that in NatA, sequences exhibiting homology to NatA were searched from genomic information of Escherichia coli K-12 strain. As a result of searching utilizing published database (EcoCyc, ecocyc.org, Keseler et al., (2005) Nucleic Acids Res., 33, 334-337) and using BLASTP, N-hydroxyarylamine O-acetyltransferase from Escherichia coli K-12 strain (convertible term: NhoA, EC: 2.3.1.118, NCBI accession ID: NP_415980.1) was found to exhibit 49% homology to NatA derived from Streptomyces griseus IFO13350 strain. An amino acid sequence of NhoA and a nucleotide sequence of a gene encoding NhoA (convertible term: nhoA: GenBank accession No.: NC_000913.2, nucleotides 1532048 to 1532893, GI: 947251) are shown as SEQ ID NO:2 and SEQ ID NO:3, respectively.
(2) Construction of Plasmid for Expressing nhoA Gene
An expression plasmid for expressing the nhoA gene in Escherichia coli was constructed by the following procedure. PCR with genomic DNA from Escherichia coli BW25113 strain as a template was carried out using the synthesized oligonucleotide having a restriction enzyme recognition sequence for HindIII at the 3′ terminus and shown as SEQ ID NO:4 and further the synthesized oligonucleotide having a restriction enzyme recognition sequence for EcoRI at the 3′ terminus and shown as SEQ ID NO:5 as primers and using PrimeStar GXL polymerase (supplied from Takara). A reaction solution was prepared according to a composition attached to the kit, and 30 cycles of the reaction at 98° C. for 10 seconds, 55° C. for 15 seconds and 68° C. for 60 seconds were carried out. As a result, a PCR product of about 1.1 kbp including a native promoter of the nhoA gene and a nhoA gene fragment was obtained. This fragment was digested with EcoRI and HindIII, and subsequently cloned into pUC19 (supplied from Takara) digested with the same restriction enzymes. The resulting vector was designated as pUC19-NhoA. The full length sequence of pUC19-NhoA is shown as SEQ ID NO:6.
(3) Construction of Expression Plasmid pSTV28-Ptac-Ttrp
An expression plasmid pSTV28-Ptac-Trp was constructed to impart an ability to produce 3,4-AHBA to Escherichia coli. First, a DNA fragment comprising a tac promoter (convertible term: Ptac) region (deBoer, et al., (1983) Proc. Natl. Acad. Sci. U.S.A., 80, 21-25) and a terminator region of a tryptophan operon (convertible term: Ttrp) derived from Escherichia coli (Wu et al., (1978) Proc. Natl. Acad. Sci. U.S.A., 75, 5442-5446) and having a KpnI site at the 5′ terminus and a BamHI site at the 3′ terminus was chemically synthesized (the nucleotide sequence is shown as SEQ ID NO:7). The resulting DNA fragment was digested with KpnI and BamHI to obtain a DNA fragment including Ptac and Ttrp. The purified DNA fragment was ligated to pSTV28 (supplied from Takara Bio Inc.) digested with KpnI and BamHI by a ligation reaction with DNA ligase. The resulting plasmid was designated as pSTV28-Ptac-Ttrp (the nucleotide sequence is shown as SEQ ID NO:8). An objective gene can be expressed and amplified by cloning the objective gene downstream of Ptac of this plasmid.
(4) Chemical Synthesis of griI Gene and griH Gene Corresponding to Codon Usage in Escherichia coli 
It has been reported that the synthesis of 3,4-AHBA is catalyzed by a 3,4-AHBA synthetase gene group consisting of aldolase (convertible term: SGR_4249, GriI) and 3,4-AHBA synthase (convertible term: SGR_4248, GriH) in Streptomyces griseus IFO13350 strain (Suzuki et. al., (2006) J. Biol. Chem., 281, 36944-36951). GriI is encoded by the griI gene (GenBank accession no. AB259663.1, nucleotides 13956 to 14780; GI: 117676060). The amino acid sequence of the GriI protein and a nucleotide sequence of the griI gene are shown as SEQ ID NO:9 and SEQ ID NO:10, respectively. Also, GriH is encoded by the griH gene (GenBank accession no. AB259663.1, nucleotides 12690 to 13880; GI: 117676059). The amino acid sequence of the GriH protein and a nucleotide sequence of the griH gene are shown as SEQ ID NO:11 and SEQ ID NO:12, respectively.
In order to efficiently express the griI gene and griH gene in Escherichia coli, the sequences of the griI gene and the griH gene were changed so as to correspond to codon usage in Escherichia coli, designed so as to express as an operon, and this was designated as EcGriIH. Restriction enzyme recognition sequences for EcoRI and HindIII were added to the 5′ terminus and the 3′ terminus of EcGriIH, respectively, and this fragment was chemically synthesized (shown as SEQ ID NO:13). EcGriIH, both termini of which the restriction enzyme recognition sequence had been added to, was digested with EcoRI and HindIII, and subsequently cloned into pUC57 (supplied from Genscript) which had been digested with the same restriction enzymes. The resulting vector was designated as pUC57-EcGri. The full length sequence of pUC57-EcGri is shown as SEQ ID NO:14.
(5) Construction of Plasmid for Expressing griI Gene and griH Gene
An expression plasmid for expressing the griI gene and the griH gene in Escherichia coli was constructed using the following procedure. PCR with pUC57-EcGri as a template was carried out using the synthesized oligonucleotide represented by SEQ ID NO:15 and further the synthesized oligonucleotide represented by SEQ ID NO:16 as primers and using PrimeStar GXL polymerase (supplied from Takara). A reaction solution was prepared according to a composition attached to the kit, and 30 cycles of the reaction at 98° C. for 10 seconds, 55° C. for 15 seconds and 68° C. for 150 seconds were carried out. As a result, a PCR product of about 2.1 kbp including an EcGriIH gene fragment was obtained. Subsequently, the purified EcGriIH gene fragment was ligated to pSTV28-Ptac-Ttrp digested with SmaI using In-Fusion HD Cloning Kit (supplied from Clontech). The resulting plasmid for expressing the griIH gene was designated as pSTV28-EcGri. The full length sequence of pSTV28-EcGri is shown as SEQ ID NO:17.
(6) Construction of 3,4-AcAHBA-Producing Bacterium
Competent cells of Escherichia coli BW25113 strain were prepared, and then pSTV28-EcGri was introduced thereto by electroporation. Subsequently the cells were uniformly applied onto an LB plate containing 30 mg/L of chloramphenicol, and cultured at 37° C. for 18 hours. A transformant exhibiting resistance to chloramphenicol was obtained from the resulting plate. A strain in which pSTV28-EcGri had been introduced into Escherichia coli BW25113 strain was designated as BW25113/pSTV28-EcGri strain. Subsequently, competent cells of BW25113/pSTV28-EcGri strain were prepared, and then pUC19 or pUC19-NhoA was introduced by the electroporation. The cells were uniformly applied onto an LB plate containing 30 mg/L of chloramphenicol and 100 mg/L of ampicillin, and cultured at 37° C. for 18 hours. A transformant exhibiting resistance to both chloramphenicol and ampicillin was obtained from the resulting plate. A strain in which pUC19 had been introduced into BW25113/pSTV28-EcGri strain was designated as BW25113/pSTV28-EcGri/pUC19 strain. A strain in which pUC19-NhoA had been introduced into BW25113/pSTV28-EcGri strain was designated as BW25113/pSTV28-EcGri/pUC19-NhoA strain.
(7) 3,4-AcAHBA-Producing Culture
Microbial cells from BW25113/pSTV28-EcGri/pUC19 strain and BW25113/pSTV28-EcGri/pUC19-NhoA strain were uniformly applied onto an LB plate containing 30 mg/L of chloramphenicol and 100 mg/L of ampicillin, and cultured at 37° C. for 18 hours. One loopful of microbial cells obtained from the resulting plate was inoculated to 4 mL of MS glucose/Asp medium containing 30 mg/L of chloramphenicol and 100 mg/L of ampicillin in a test tube, and cultured on a reciprocal shaking cultivation apparatus at 30° C. for 48 hours. A composition of the MS glucose/Asp medium is as described in the following Table 1.







TABLE 1







Table 1. Composition of MS glucose/Asp medium











Final



Component
concentration















Glucose
40
(g/L)



(NH4)2SO4
24
(g/L)



Aspartic acid
5
(g/L)



KH2PO4
1
(g/L)



MgSO4•7H2O
1
(g/L)



FeSO4•7H2O
10
(mg/L)



MnSO4•7H2O
82
(mg/L)



Bacto-yeast extract
2
(g/L)



CaCO3
50
(g/L)










The medium was adjusted to pH 7.0 with KOH, and autoclaved at 121° C. for 20 minutes. But, glucose and MgSO4.7H2O were mixed and separately sterilized. CaCO3 was added after dry-heat sterilization.
(8) Analysis of Molecular Weight of Compound (R.T., 9.5 Minutes) Converted from 3,4-AHBA
Charts obtained from reverse phase column chromatography for culture supernatants of BW25113/pSTV28-EcGri/pUC19 strain and BW25113/pSTV28-EcGri/pUC19-NhoA strain described in Example 1 (7) and a 3,4-AHBA standard preparation (Cat No. A0859 supplied from Tokyo Chemical Industry Co., Ltd.) are shown in FIG. 1 (The analysis condition was described in Suzuki et. al., (2006) J. Biol. Chem., 281, 36944-36951). No 3,4-AHBA was detected in the culture supernatant of BW25113/pSTV28-EcGri/pUC19-NhoA strain, and the height of a peak detected at retention time (R.T.) of 9.5 minutes was found to increase compared with that of BW25113/pSTV28-EcGri/pUC19 that was a control. This suggested that 3,4-AHBA was converted into a compound detected at R.T. of 9.5 minutes by overexpressed NhoA.
The molecular weight of the compound (R.T., 9.5 minutes) converted from 3,4-AHBA which was contained in the culture supernatant after the cultivation of cells from BW25113/pSTV28-EcGri/pUC19-NhoA strain was analyzed by LC/MS. The analysis condition is as follows.

    
    
        Column: Inertsil ODS-3 2 μm, 2.1×75 mm (supplied from GL Science)
        Mobile phase: A=0.1% formic acid/H2O
        B=0.1% formic acid/acetonitrile
        Gradient Program
    
    


















 0 minute
A/B = 100/0



 3 minutes
A/B = 100/0



23 minutes
A/B = 20/80



25 minutes
A/B = 20/80










    
    
        Flow rate: 0.2 mL/minute
        Column temperature: Room temperature (25° C.)
        Detection wavelength: 254 nm (PDA)
        MS ionization mode: ESI
        Analysis machines: Agilent Infinity 1290 (LC)
        Agilent Quadrupole LC/MS 6130 (MS)
    
    


As a result of the analysis, the m/z value of the converted compound (R.T., 9.5 minutes) was 195.1, and matched with the calculated m/s value of acetylated 3,4-AHBA (195.1). Hereinafter, the converted compound (R.T., 9.5 minutes) is referred to as 3,4-AcAHBA.
(9) Absorbance of Culture Medium and Quantification of Accumulated 3,4-AHBA and 3,4-AcAHBA in Culture Supernatant
Optical density (OD) values of culture media of cells from BW25113/pSTV28-EcGri/pUC19 strain and BW25113/pSTV28-EcGri/pUC19-NhoA strain described in Example 1 (7) at 600 nm were measured using a spectrophotometer (HITACHI U-2900). 3,4-AHBA and 3,4-AcAHBA accumulated in a culture supernatant were separated by reverse phase column chromatography and their accumulated amounts were quantified (Suzuki et. al., (2006) J. Biol. Chem., 281, 36944-36951). The OD values of the culture media at 600 nm, the amount of accumulated 3,4-AHBA, and the amount of accumulated 3,4-AcAHBA were shown in Table 2. No 3,4-AHBA was detected and the amount of accumulated 3,4-AcAHBA increased in the culture supernatant of BW25113/pSTV28-EcGri/pUC19-NhoA strain compared with the culture supernatant of BW25113/pSTV28-EcGri/pUC19 strain that was the control. The sum of the concentration of 3,4-AHBA and the concentration of 3,4-AcAHBA in the culture supernatant of BW25113/pSTV28-EcGri/pUC19-NhoA strain was 1.67 times larger than that of BW25113/pSTV28-EcGri/pUC19 strain.







TABLE 2







Table 2. Accumulated amounts of 3,4-AHBA and 3,4-AcAHBA and


their summation in culture supernatant of Escherichia coli transformed


with 3,4-AHBA synthetase gene group derived from Streptomyces


griseus and nhoA gene derived from Escherichia coli















Sum of






accumulated






3,4-




Amount of
Amount of
AHBA and




accumulated
accumulated 3,
accumulated



OD
3,4-AHBA
4-AcAHBA
3,4-AcAHBA


Strain name
(600 nm)
(g/L)
(g/L)
(g/L)





BW25113/
30.3 ± 1.3
0.08 ± 0.01
0.43 ± 0.01
0.51 ± 0.01


pSTV28-


EcGri/


pUC19


BW25113/
24.5 ± 0.6
N.D.
0.85 ± 0.03
0.85 ± 0.03


pSTV28-


EcGri/


pUC19-


NhoA





N.D.: not detected


Each value is represented as a mean value obtained from cultivations in triplicate.






Example 2
Construction of 3,4-AHBA producing bacterium by introducing 3,4-AHBA synthetase gene group derived from Streptomyces murayamaensis and nhoA gene derived from Escherichia coli into Escherichia coli, and evaluation of amount of accumulated 3,4-AcAHBA
(1) Chemical Synthesis of nspI Gene and nspH Gene Corresponding to Codon Usage in Escherichia coli 
It has been already known that the synthesis of 3,4-AHBA is catalyzed by the 3,4-AHBA synthetase gene group consisting of aldolase (convertible term: NspI; NCBI accession ID:BAJ08171.1) and 3,4-AHBA synthase (convertible term: NspH; NCBI accession ID:BAJ08172.1) in Streptomyces murayamaensis (Noguchi et. al., (2010) Nat. Chem. Biol., 6,641-643). NspI is encoded by the nspI gene (GenBank accession No. AB530136, nucleotides 8730 to 9584; GI: 296784943). The amino acid sequence of the NspI protein and the nucleotide sequence of the nspI gene are shown as SEQ ID NO:18 and SEQ ID NO:19, respectively. Also, NspH is encoded by the nspH gene (GenBank accession No. AB530136, nucleotides 9599 to 10702; GI: 296784944). The amino acid sequence of the NspH protein and the nucleotide sequence of the nspH gene are shown as SEQ ID NO:20 and SEQ ID NO:21, respectively.
In order to efficiently express the nspI gene and nspH gene in Escherichia coli, the sequences of the nspI gene and the nspH gene were changed so as to correspond to codon usage in Escherichia coli, designed so as to express as an operon, and this was designated as EcNspIH. Restriction enzyme recognition sequences for EcoRI and HindIII were added to the 5′ terminus and the 3′ terminus of EcNspIH, respectively, and this fragment was chemically synthesized. EcNspIH, both termini of which the restriction enzyme recognition sequence had been added to, was digested with EcoRI and HindIII, and then cloned into pUC57 (supplied from Genscript) digested with the same restriction enzymes. The resulting vector was designated as pUC57-EcNsp.
(2) Construction of Plasmid for Expressing nspI Gene and nspH Gene
An expression plasmid for expressing the nspI gene and the nspH gene in Escherichia coli was constructed using the following procedure. PCR with pUC57-EcNsp as a template was carried out using the synthesized oligonucleotides as primers and using PrimeStar GXL polymerase (supplied from Takara). A reaction solution was prepared according to a composition attached to the kit, and 30 cycles of the reaction at 98° C. for 10 seconds, 55° C. for 15 seconds and 68° C. for 150 seconds were carried out. As a result, a PCR product of about 2.1 kbp comprising an EcNspIH gene fragment was obtained. Subsequently, the purified EcNspIH gene fragment was ligated to pSTV28-Ptac-Ttrp [described in Example 1 (3)] digested with SmaI using In-Fusion HD Cloning Kit (supplied from Clontech). The resulting plasmid for expressing the nspIH gene was designated as pSTV28-EcNsp.
(3) Construction of 3,4-AcAHBA-Producing Bacterium
Competent cells of Escherichia coli BW25113 strain were prepared, and then pSTV28-EcNsp was introduced thereto by electroporation. The cells were uniformly applied onto an LB plate containing 30 mg/L of chloramphenicol, and cultured at 37° C. for 18 hours. A transformant exhibiting resistance to chloramphenicol was obtained from the resulting plate. A strain in which pSTV28-EcNsp had been introduced into Escherichia coli BW25113 strain was designated as BW25113/pSTV28-EcNsp strain. Subsequently, competent cells of BW25113/pSTV28-EcNsp strain were prepared, and pUC19 or pUC19-NhoA [described in Example 1 (2)] was introduced by electroporation. The cells were uniformly applied onto an LB plate containing 30 mg/L of chloramphenicol and 100 mg/L of ampicillin, and cultured at 37° C. for 18 hours. A transformant exhibiting resistance to both chloramphenicol and ampicillin was obtained from the resulting plate. A strain in which pUC19 had been introduced into BW25113/pSTV28-EcNsp strain was designated as BW25113/pSTV28-EcNsp/pUC19 strain. A strain in which pUC19-NhoA had been introduced into BW25113/pSTV28-EcNsp strain was designated as BW25113/pSTV28-EcNsp/pUC19-NhoA strain.
(4) Evaluation of 3,4-AcAHBA-Producing Culture
Microbial cells from BW25113/pSTV28-EcNsp/pUC19 strain and BW25113/pSTV28-EcNsp/pUC19-NhoA strain were uniformly applied onto an LB plate containing 30 mg/L of chloramphenicol and 100 mg/L of ampicillin, and cultured at 37° C. for 18 hours. One loopful of microbial cells obtained from the resulting plate was inoculated to 4 mL of MS glucose/Asp medium containing 30 mg/L of chloramphenicol and 100 mg/L of ampicillin in a test tube, and cultured on the reciprocal shaking cultivation apparatus at 30° C. for 48 hours. The composition of the MS glucose/Asp medium is as described in Table 1.
After the cultivation, OD values of the culture media at 600 nm were measured using the spectrophotometer (HITACHI U-2900). Also, 3,4-AHBA and 3,4-AcAHBA accumulated in the culture supernatant were separated by reverse phase column chromatography and their amounts were measured in the same manner as in Example 1. The OD values of the culture media at 600 nm, the amount of accumulated 3,4-AHBA, and the amount of accumulated 3,4-AcAHBA were shown in Table 3. No 3,4-AHBA was detected and the amount of accumulated 3,4-AcAHBA increased in the culture supernatant of BW25113/pSTV28-EcNsp/pUC19-NhoA strain compared with the culture supernatant of BW25113/pSTV28-EcNsp/pUC19 strain that was the control. The sum of the concentration of 3,4-AHBA and the concentration of 3,4-AcAHBA in the culture supernatant of BW25113/pSTV28-EcNsp/pUC19-NhoA strain was 1.69 times larger than that of BW25113/pSTV28-EcNsp/pUC19 strain.







TABLE 3







Table 3. Accumulated amounts of 3,4-AHBA and 3,4-AcAHBA and


their summation in culture supernatant of Escherichia coli transformed


with 3,4-AHBA synthetase gene group derived from Streptomyces


murayamaensis and nhoA gene derived from Escherichia coli















Sum of






Accumulated






3,4-AHBA




Amount of
Amount of
and




accumulated
accumulated
accumulated



OD
3, 4-AHBA
3,4-AcAHBA
3,4-AcAHBA


Strain name
(600 nm)
(g/L)
(g/L)
(g/L)





BW25113/
32.4 ± 2.2
0.24 ± 0.02
0.43 ± 0.03
0.67 ± 0.03


pSTV28-


EcNsp/


pUC19


BW25113/
25.1 ± 1.4
N.D.
1.13 ± 0.08
1.13 ± 0.08


pSTV28-


EcNsp/


pUC19-


NhoA





N.D.: not detected


Each value is represented as a mean value obtained from cultivations in triplicate.






Example 3
Construction of 3,4-AcAHBA producing bacterium by introducing 3,4-AHBA synthetase gene group derived from Streptomyces griseus and nhoA gene derived from Escherichia coli into Pantoea ananatis, and evaluation of amount of accumulated 3,4-AcAHBA
(1) Construction of Plasmid for Expressing nhoA Gene
An expression plasmid for expressing the nhoA gene in Pantoea ananatis was constructed using the following procedure. PCR with genomic DNA from Escherichia coli BW25113 strain as a template was carried out using the synthesized oligonucleotide having a restriction enzyme recognition sequence for HindIII at the 3′ terminus and represented by SEQ ID NO:4 and further the synthesized oligonucleotide having a restriction enzyme recognition sequence for EcoRI at the 3′ terminus and represented by SEQ ID NO:5 as primers and using PrimeStar GXL polymerase (supplied from Takara). A reaction solution was prepared according to a composition attached to the kit, and 30 cycles of the reaction at 98° C. for 10 seconds, 55° C. for 15 seconds and 68° C. for 60 seconds were carried out. As a result, a PCR product of about 1.1 kbp comprising a native promoter of the nhoA gene and an nhoA gene fragment was obtained. This fragment was digested with EcoRI and HindIII, and then cloned into pMW219 (supplied from Takara) digested with the same restriction enzymes. The resulting vector was designated as pMW219-NhoA. The full length sequence of pMW219-NhoA is shown as SEQ ID NO:22.
(2) Construction of 3,4-AcAHBA-Producing Bacterium
Competent cells of Pantoea ananatis SC17 strain (described in JP 2006-230202-A) were prepared, and then pSTV28-EcGri was introduced thereto by electroporation. The cells were uniformly applied onto an LB plate containing 30 mg/L of chloramphenicol, and cultured at 30° C. for 24 hours. A transformant exhibiting resistance to chloramphenicol was obtained from the resulting plate. A strain in which pSTV28-EcGri had been introduced into Pantoea ananatis SC17 strain was designated as SC17/pSTV28-EcGri strain. Subsequently, competent cells of SC17/pSTV28-EcGri strain were prepared, and then pMW219 or pMW219-NhoA was introduced by electroporation. The cells were uniformly applied onto an LB plate containing 30 mg/L of chloramphenicol and 50 mg/L of kanamycin, and cultured at 30° C. for 24 hours. A transformant exhibiting resistance to both chloramphenicol and kanamycin was obtained from the resulting plate. A strain in which pMW219 had been introduced into SC17/pSTV28-EcGri strain was designated as SC17/pSTV28-EcNsp/pMW219 strain. A strain in which pMW219-NhoA had been introduced into SC17/pSTV28-EcGri strain was designated as SC17/pSTV28-EcGri/pMW219-NhoA strain.
(3) Evaluation of 3,4-AcAHBA-Producing Culture
Microbial cells from SC17/pSTV28-EcGri/pMW219 strain and SC17/pSTV28-EcGri/pMW219-NhoA strain were uniformly applied onto an LB plate containing 30 mg/L of chloramphenicol and 50 mg/L of kanamycin, and cultured at 30° C. for 24 hours. One loopful of microbial cells obtained from the resulting plate was inoculated to 4 mL of MS glucose/Asp medium containing 30 mg/L of chloramphenicol and 50 mg/L of kanamycin in a test tube, and cultured on the reciprocal shaking cultivation apparatus at 30° C. for 32 hours. The composition of the MS glucose/Asp medium is as described in Table 1.
After the cultivation, OD values at 600 nm of the culture media were measured using the spectrophotometer (HITACHI U-2900). Also, 3,4-AHBA and 3,4-AcAHBA accumulated in the culture supernatant were separated by reverse phase column chromatography and their amounts were measured in the same manner as in Example 1 (9). The OD values at 600 nm of the culture media, the amount of accumulated 3,4-AHBA, and the amount of accumulated 3,4-AcAHBA were shown in Table 4. No 3,4-AHBA was detected and the amount of accumulated 3,4-AcAHBA increased in the culture supernatant of SC17/pSTV28-EcGri/pMW219-NhoA strain compared with that in the culture supernatant of SC17/pSTV28-EcGri/pMW219 strain that was the control. The sum of the concentration of 3,4-AHBA and the concentration of 3,4-AcAHBA in the culture supernatant of SC17/pSTV28-EcGri/pMW219-NhoA strain was 2.46 times larger than that of SC17/pSTV28-EcGri/pMW219 strain.







TABLE 4







Table 4. Accumulated amounts of 3,4-AHBA and 3,4-AcAHBA


and their summation in culture supernatant of Pantoea ananatis


transformed with 3,4-AHBA synthetase gene group derived


from Streptomyces griseus and nhoA gene derived from


Escherichia coli















Sum of






accumulated




Amount of
Amount of
3,4-AHBA and




accumulated
accumulated
accumulated



OD
3,4-AHBA
3,4-AcAHBA
3,4-AcAHBA


Strain name
(600 nm)
(g/L)
(g/L)
(g/L)





SC17/
15.2 ± 0.6
0.39 ± 0.00
N.D.
0.39 ± 0.00


pSTV28-


EcGri/


pMW219


SC17/
16.8 ± 1.0
N.D.
0.96 ± 0.05
0.96 ± 0.05


pSTV28-


EcGri/


pMW219-


NhoA





N.D.: not detected


Each value is represented as a mean value obtained from cultivations in triplicate.






Example 4
Construction of 3,4-AcAHBA-producing bacterium by introducing 3,4-AHBA synthetase gene group derived from Streptomyces griseus and nhoA gene derived from Escherichia coli into Corynebacterium glutamicum, and evaluation of amount of accumulated 3,4-AcAHBA
(1) Construction of Plasmid for Expressing nhoA Gene
An expression plasmid for expressing the nhoA gene in Corynebacterium glutamicum was constructed using the following procedure. PCR with genomic DNA from Escherichia coli BW25113 strain as a template was carried out using the synthesized oligonucleotide having a restriction enzyme recognition sequence for HindIII at the 3′ terminus and represented by SEQ ID NO:4 and further the synthesized oligonucleotide having a restriction enzyme recognition sequence for EcoRI at the 3′ terminus and represented by SEQ ID NO:5 as primers and using PrimeStar GXL polymerase (supplied from Takara). A reaction solution was prepared according to a composition attached to the kit, and 30 cycles of the reaction at 98° C. for 10 seconds, 55° C. for 15 seconds and 68° C. for 60 seconds were carried out. As a result, a PCR product of about 1.1 kbp comprising a native promoter of the nhoA gene and an nhoA gene fragment was obtained. This fragment was digested with EcoRI and HindIII, and then cloned into pVC7 (described in JP 9-070291-A) digested with the same restriction enzymes. The resulting vector was designated as pVC7-NhoA. The full length sequence of pVC7-NhoA is shown as SEQ ID NO:23.
(2) Construction of 3,4-AcAHBA-Producing Bacterium
A plasmid pPK4griIH described in JP 2010-005099-A was used in order to express the griI gene and the griH gene in Corynebacterium glutamicum. pPK4griIH includes a sequence connecting the griI gene and the griH gene downstream of a promoter sequence of a cell surface protein gene derived from Corynebacterium glutamicum ATCC 13869 strain (Peyret et al., (1993) Mol. Microbiol., 9, 97-109), and is a plasmid capable of efficiently expressing the griI gene and the griH gene in Corynebacterium glutamicum. Competent cells of Corynebacterium glutamicum ATCC 13869 strain were prepared, and then pPK4griIH was introduced thereto by electroporation. The cells were then applied uniformly onto a CMDex plate containing 25 mg/L of kanamycin, and cultured at 30° C. for 24 hours. The composition of the CMDex plate is shown in following Table 5.







TABLE 5







Table 5. Composition of CMDex









Final


Component
concentration












Glucose
5
(g/L)


KH2PO4
1
(g/L)


MgSO4•7H2O
0.4
(g/L)


FeSO4•7H2O
10
(mg/L)


MnSO4•5H2O
10
(mg/L)


Polypeptone
10
(g/L)


Bacto-yeast extract
10
(g/L)


Urea
3
(g/L)


Hydrolyzed soybean product (as total nitrogen content)
1.2
(g/L)


Biotin
10
(μg/L)


Agar
20
(g/L)









The pH value was adjusted to 7.5 with KOH. The components were autoclaved at 121° C. for 20 minutes, but agar was added after adjusting the pH value.
A transformant exhibiting resistance to kanamycin was obtained from the resulting plate. A strain in which pPK4griIH had been introduced into Corynebacterium glutamicum ATCC 13869 strain was designated as ATCC13869/pPK4griIH strain. Subsequently, competent cells of ATCC13869/pPK4griIH strain were prepared, and then pCV7 or pCV7-NhoA was introduced by electroporation. The cells were then applied uniformly onto a CMDex plate containing 20 mg/L of kanamycin and 5 mg/L of chloramphenicol, and cultured at 30° C. for 24 hours. A transformant exhibiting resistance to both kanamycin and chloramphenicol was obtained from the resulting plate. A strain in which pVC7 had been introduced into ATCC13869/pPK4griIH strain was designated as ATCC13869/pPK4griIH/pVC7 strain. A strain in which pVC7-NhoA had been introduced into ATCC13869/pPK4griIH strain was designated as ATCC13869/pPK4griIH/pVC7-NhoA strain.
(3) Evaluation of 3,4-AcAHBA-Producing Culture
Microbial cells from ATCC13869/pPK4griIH/pVC7 strain and ATCC13869/pPK4griIH/pVC7-NhoA strain were uniformly applied onto a CMDex plate containing 20 mg/L of kanamycin and 5 mg/L of chloramphenicol, and cultured at 30° C. for 24 hours. One loopful of microbial cells obtained from the resulting plate was inoculated to 4 mL of a medium for producing 3,4-AcAHBA and containing 20 mg/L of kanamycin and 5 mg/L of chloramphenicol in a test tube, and cultured on the reciprocal shaking cultivation apparatus at 30° C. for 56 hours. The composition of the medium for producing 3,4-AcAHBA is as described in following Table 6.







TABLE 6







Table 6. Composition of medium for producing 3,4-AcAHBA











Final



Component
concentration















Glucose
100
(g/L)



(NH4)2SO4
55
(g/L)



KH2PO4
1
(g/L)



MgSO4•7H2O
1
(g/L)



FeSO4•7H2O
10
(mg/L)



MnSO4•7H2O
10
(mg/L)



Hydrolyzed soybean product (as total
1.05
(g/L)



nitrogen content)



Nicotine amide
5
(mg/L)



Thiamine hydrochloride
2
(mg/L)



Biotin
0.5
(mg/L)



CaCO3
50
(g/L)










The pH value was adjusted to 7.5 with KOH. The components were autoclaved at 121° C. for 20 minutes, but glucose and MgSO4.7H2O were mixed and sterilized separately. CaCO3 was added after dry-heat sterilization.
After the cultivation, OD values at 600 nm of the culture media were measured using the spectrophotometer (HITACHI U-2900). Also, 3,4-AHBA and 3,4-AcAHBA accumulated in the culture supernatant were separated by reverse phase column chromatography and their amounts were measured in the same manner as in Example 1 (9). The OD values at 600 nm of the culture media, the amount of accumulated 3,4-AHBA, and the amount of accumulated 3,4-AcAHBA were shown in Table 7. No 3,4-AHBA was accumulated and the amount of accumulated 3,4-AcAHBA increased in the culture supernatant of ATCC13869/pPK4griIH/pVC7-NhoA strain compared with that in the culture supernatant of ATCC13869/pPK4griIH/pVC7 strain that was the control.







TABLE 7







Table 7. Accumulated amounts of 3,4-AHBA and 3,4-AcAHBA


and their summation in culture supernatant of Corynebacterium


glutamicum transformed with 3,4-AHBA synthetase gene group


derived from Streptomyces griseus and nhoA gene derived from


Escherichia coli















Sum of






Amount of






accumulated






3,4-AHBA





Amount of
and




Amount of
accumulated
accumulated




accumulated
3,4-
3,4-



OD
3,4-AHBA
AcAHBA
AcAHBA


Strain name
(600 nm)
(g/L)
(g/L)
(g/L)





ATCC13869/
95.5 ± 2.4
0.48 ± 0.00
N.D.
0.48 ± 0.00


pPK4griIH/


pVC7


ATCC13869/
97.5 ± 3.4
N.D.
0.48 ± 0.00
0.48 ± 0.00


pPK4griIH/


pVC7-


NhoA





N.D.: not detected


Each value is represented as a mean value obtained from cultivations in triplicate.






INDUSTRIAL APPLICABILITY
According to the present invention, it is possible to conveniently and efficiently produce acetylamino-hydroxybenzoic acid-type compounds that can easily be converted to amino-hydroxybenzoic acid-type compounds that are useful as intermediates for dyes, agricultural chemicals, pharmaceuticals and other organic synthesized products and as monomers of polybenzoxazoles. Therefore, for example, 3-acetylamono-4-hydroxybenzoic acid obtained as described herein is converted to 3-amino-4-hydroxybenzoic acid and then the converted 3-amino-4-hydroxybenzoic acid is polymerized to yield polybenzoxazole (PBO), thereby being capable of inexpensively providing PBO fibers and PBO films having high intensity, high elastic modulus and high heat resistance. The 3-acetylamino-4-hydroxybenzoic acid-type compound that is a stable compound and can easily be converted to the 3-amino-4-hydroxybenzoic acid-type compound that is a raw material can be produced by biosynthesis. Thus, the method as described herein is a process with low environmental load and is friendly for the global environment.
While the invention has been described in detail with reference to preferred embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. Each of the aforementioned documents is incorporated by reference herein in its entirety.

## Claims

1. A method for producing 3-acetylamino-4-hydroxybenzoic acid or a salt thereof, comprising:
a) culturing a microorganism so that 3-acetylamino-4-hydroxybenzoic acid or a salt thereof is produced, and
b) collecting said 3-acetylamino-4-hydroxybenzoic acid or salt thereof;
wherein the microorganism is transformed with a recombinant vector encoding a GriI protein, a GriH protein, or GriI and GriH proteins, and has increased formation of 3-amino-4-hydroxybenzoic acid from dihydroxyacetone phosphate and aspartate semialdehyde as compared to the same microorganism that does not comprise said recombinant vector, and
wherein the microorganism is transformed with a recombinant vector encoding a N-hydroxyarylamine O-acetyltransferase (NhoA) protein and has increased NhoA activity as compared to the same microorganism that does not comprise said recombinant vector, and wherein said NhoA protein is selected from the group consisting of:
(I) a protein comprising the amino acid sequence of SEQ ID NO: 2;
(II) a protein comprising the amino acid sequence of SEQ ID NO: 2, but having no more than one to ten amino acid substitutions, deletions, insertions or additions, and wherein said protein has NhoA activity;
(III) a protein comprising an amino acid sequence having 95% or more sequence identity to the amino acid sequence of SEQ ID NO:2 and having NhoA activity; and
(IV) combinations thereof.

2. A method for producing 3-amino-4-hydroxybenzoic acid, or a salt thereof, comprising:
(1) producing the 3-acetylamino-4-hydroxybenzoic acid or the salt thereof by the method according to claim 1; and
(2) deacetylating the 3-acetylamino-4-hydroxybenzoic acid or the salt thereof to form the 3-amino-4-hydroxybenzoic acid or the salt thereof.

3. A method for producing a polymer containing a 3-amino-4-hydroxybenzoic acid or a salt thereof as a component, comprising:
(1′) forming the 3-amino-4-hydroxybenzoic acid or the salt thereof by the method according to claim 2; and
(2′) polymerizing the 3-amino-4-hydroxybenzoic acid or the salt thereof to obtain a polymer containing the 3-amino-4-hydroxybenzoic acid or the salt thereof as a component.

4. The method according to claim 3, wherein the polymer is a polybenzoxazole polymer.

5. The method according to claim 1, wherein the NhoA protein is encoded by a DNA selected from the group consisting of:
(i) a DNA comprising the nucleotide sequence of SEQ ID NO: 3;
(ii) a DNA that hybridizes under stringent conditions with the nucleotide sequence complementary to the nucleotide sequence of SEQ ID NO:3 and encodes a protein having NhoA activity;
(iii) a DNA comprising a nucleotide sequence having 95% or more sequence identity to the nucleotide sequence of SEQ ID NO:3 and encodes a protein having NhoA activity; and
(iv) combinations thereof; and
wherein the stringent conditions include hybridization in 6×SSC at 45° C. followed by one or more washings in 0.2×SSC and 0.1% SDS at 50 to 65° C.

6. The method according to claim 1, wherein the microorganism belongs to the genus Escherichia, the genus Pantoea, or the genus Corynebacterium.

7. The method according to claim 1, wherein the microorganism is Escherichia coli, Pantoea ananatis, or Corynebacterium glutamicum.

8. The method according to claim 1, wherein said recombinant vector encodes GriI and GriH proteins.

9. The method according to claim 1, wherein said GriI protein is selected from the group consisting of:
(A) a protein comprising the amino acid sequence of SEQ ID NO:9 or SEQ ID NO: 18;
(B) a protein comprising the amino acid sequence of SEQ ID NO: 9 or SEQ ID NO: 18, but having no more than one to ten amino acid substitutions, deletions, insertions or additions in said amino acid sequence and said protein having aldolase activity;
(C) a protein comprising an amino acid sequence having 95% or more sequence identity to the amino acid sequence of SEQ ID NO: 9 or SEQ ID NO: 18 and having aldolase activity; and
(D) combinations thereof; and
wherein said GriH protein is selected from the group consisting of:
(E) a protein comprising the amino acid sequence of SEQ ID NO: 11 or SEQ ID NO:20;
(F) a protein comprising the amino acid sequence of SEQ ID NO: 11 or SEQ ID NO:20, but having no more than one to ten amino acid substitutions, deletions, insertions or additions in said amino acid sequence and said protein having 3-amino-4- hydroxybenzoic acid synthase activity;
(G) a protein comprising an amino acid sequence having 95% or more sequence identity to the amino acid sequence of SEQ ID NO: 11 or SEQ ID NO:20 and having 3-amino-4-hydroxybenzoic acid synthase activity; and
(H) combinations thereof.

10. The method according to claim 1, wherein said GriI protein is encoded by a DNA selected from the group consisting of:
(a) a DNA comprising the nucleotide sequence of SEQ ID NO: 10 or SEQ ID NO:19;
(b) a DNA that hybridizes under stringent conditions with the nucleotide sequence complementary to the nucleotide sequence of SEQ ID NO: 10 or SEQ ID NO: 19 and wherein said DNA encodes a protein having aldolase activity;
(c) a DNA that has 95% or more sequence identity to the nucleotide sequence of SEQ ID NO: 10 or SEQ ID NO: 19 and encodes a protein having aldolase activity; and
wherein said GriH protein is encoded by a DNA selected from the group consisting of:
(d) a DNA comprising the nucleotide sequence of SEQ ID NO: 12 or SEQ ID NO:21;
(e) a DNA that hybridizes under stringent conditions with the nucleotide sequence complementary to the nucleotide sequence of SEQ ID NO:12 or SEQ ID NO: 21 and wherein said DNA encodes a protein having 3-amino-4-hydroxybenzoic acid synthase activity; and
(f) a DNA that has 95% or more sequence identity to the nucleotide, sequence of SEQ ID NO:12 or SEQ ID NO:21 and encodes a protein having 3-amino-4-hydroxybenzoic acid synthase activity; and
(g) combinations thereof; and
wherein the stringent conditions include hybridization in 6×SSC at 45° C. followed by one or more washings in 0.2×SSC and 0.1% SDS at 50 to 65° C.