Patent Description:
Ornithine, which is a material widely found in plants, animals, and microorganisms, is biosynthesized from glutamate, and is used as a precursor in the biosynthesis of putrescine, citrulline, and proline. Further, ornithine plays an important role in the pathway for excretion of urea produced from amino acids or ammonia by the ornithine cycle in the in vivo metabolism of higher animals. Ornithine is effective in enhancing muscle growth and reducing body fat and thus is used as nutrient supplements and also as pharmaceutical drugs for improving liver cirrhosis and liver function disorders. The known methods for producing ornithine include treatment of milk casein with digestive enzymes and use of transformed E. coli or a microorganism of the genus Corynebacterium (<CIT>; <NPL>).

Putrescine (or <NUM>,<NUM>-butanediamine) is a very important raw material for the production of polyamide-<NUM>,<NUM> including nylon-<NUM>,<NUM>, and can be produced on an industrial scale by hydrogenation of succinonitrile, which is produced from acrylonitrile by addition of hydrogen cyanide. The synthesis pathway of these chemical substances requires non-renewable petrochemical products as raw materials. Additionally, high temperature and pressure, which are implicated with the use of expensive catalyst systems, as well as relatively complex preparation steps and equipment are also needed. Accordingly, as an alternative to the chemical production process, a process of producing putrescine from a renewable biomass-derived carbon source is required. Recently, studies have been continuously conducted to use environment-friendly microorganisms for the production of industrially available high-concentration polyamines (putrescine) (<NPL>; <NPL>).

Meanwhile, NCgl2522 has been identified as a gene having an ability to export putrescine (<CIT>). However, in order to produce putrescine in a higher yield, there is still a need to develop a protein with an improved ability to export putrescine, which can more effectively export putrescine from a putrescine-producing strain.

L-arginine has been widely used in medicines as hepatic function-promoting agents, brain function-promoting agents, and as ingredients of multiple amino acid supplements. Additionally, L-arginine has gained much interest in food industry as a food additive for fish cakes and health beverages, and as a salt substitute for hypertension patients. Studies have been continuously conducted to use microorganisms for the production of industrially available high-concentration arginine, and examples thereof include a method of using a mutant strain induced from the microorganism belonging to the genus Brevibacterium or Corynebacterium, which is a glutamate-producing strain, or a method of using an amino acid-producing strain, whose growth is improved through cell fusion. Meanwhile, lysE of the microorganism belonging to the genus Corynebacterium having an ability to export L-lysine has also been shown to export the same basic amino acid L-arginine (<NPL>). Further, a method for enhancing the production ability of L-arginine-producing strains through the enhancement of the gene above has been known (<CIT>).

<CIT> describes a process for preparing terminal amino carboxylic acids and amino aldehydes from diamines by means of a recombinant microorganism. Specifically, it describes a process for preparing gamma-aminobutyric acid (GABA) or gamma-aminobutyraldehyde (ABAL) using the recombinant microorganism.

The database geneseq. Accession No. BCE12454 (XP <NUM>) describes a Corynebacterium glutamicum major facilitator superfamily permease cgmA.

<NPL>) describes the elimination of polyamine N-acetylation and regulatory engineering putrescine production by Corynebacterium glutamicum.

<CIT> relates to a recombinant microorganism capable of producing putrescine with high yield and a method of producing putrescine using said microorganism.

<NPL>) describes the roles of export genes cgmA and lysE for the production of L-arginine and L-citrulline by Corynebacterium glutamicum.

The present inventors have made extensive efforts to develop a variant of an export protein capable of further improving the production ability by enhancing the ability to export an ornithine product, and as a result, it was confirmed that the ability to export an ornithine-based product was enhanced when a modification was introduced on a specific site of the amino acid sequence of the NCgl2522 protein. Accordingly, they have found that putrescine or arginine, which is an ornithine-based product, can be produced in high yield by introducing the protein variant into putrescine- or arginine-producing strains, thereby completing the present invention.

One object of the present invention is to provide a polypeptide having an ability to export an ornithine-based product.

Another object of the present invention is to provide a polynucleotide encoding the polypeptide, and a vector comprising the polynucleotide.

Still another object of the present invention is to provide a microorganism of the genus Corynebacterium producing an ornithine-based product, comprising the polypeptide or having an enhanced activity of the polypeptide.

Still another object of the present invention is to provide a method for producing an ornithine-based product, comprising:.

The polypeptide having an ability to export an ornithine-based product of the present invention shows an excellent activity for exporting an ornithine-based product and thus, the ability to produce an ornithine-based product can be further improved when such an activity is introduced into a microorganism producing an ornithine-based product.

The present invention will be described in detail as follows.

In order to achieve the objects above, an aspect of the present invention provides a polypeptide having an ability to export an ornithine-based product, wherein the alanine residue at position <NUM> from the N-terminus of the amino acid sequence of an ornithine-based product-exporting protein, which consists of an amino acid sequence of SEQ ID NO: <NUM> or SEQ ID NO: <NUM>, is substituted with other amino acids.

Thus, as used herein, the ornithine-based product-exporting protein refers to a protein, which plays a role in the extracellular export of the products biosynthesized from ornithine as a precursor, and specifically refers to a protein, which plays a role in the extracellular export of putrescine or arginine. The NCgl2522 protein as disclosed in <CIT> can be used. The NCgl2522 protein consisting of an amino acid sequence of SEQ ID NO: <NUM> or SEQ ID NO: <NUM>, but any sequence having the activity identical to the protein can be used, and the sequence information thereof can be obtained from GenBank of NCBI, a known database.

The polypeptide having an ability to export an ornithine-based product of the present invention has a feature in which the alanine residue at position <NUM> from the N-terminus of the amino acid sequence of an ornithine-based product-exporting protein, which consists of an amino acid sequence of SEQ ID NO: <NUM> or SEQ ID NO: <NUM>, is substituted with other amino acids, and thus has an improved ability to export an ornithine-based product as compared to a non-modified polypeptide, specifically, a polypeptide having an alanine residue at position <NUM>. The other amino acids may include serine, asparagine, histidine, proline, lysine, glutamic acid, cysteine, glutamine, or methionine. Therefore, the polypeptide having an ability to export an ornithine-based product may be, for example, those in which the alanine at position <NUM> in the amino acid sequence of an ornithine-based product-exporting protein, which consists of an amino acid sequence of SEQ ID NO: <NUM> or SEQ ID NO: <NUM>, is substituted with serine, asparagine, histidine, proline, lysine, glutamic acid, cysteine, glutamine, or methionine. Specifically, the polypeptide may be a polypeptide consisting of an amino acid sequence of any one of SEQ ID NO: <NUM> to SEQ ID NO: <NUM>, or an amino acid sequence having a homology or identity thereto of <NUM>% or more, specifically <NUM>% or more, more specifically <NUM>% or more, even more specifically <NUM>% or more, even more specifically <NUM>% or more, and even more specifically <NUM>% or more, as long as it has an ability to export putrescine by substitution of alanine at position <NUM> with other amino acids. An amino acid sequence with deletion, modification, substitution, or addition of a part of the sequence can be used as long as the amino acid sequence has a biological activity substantially identical or corresponding to the polypeptide consisting of the amino acid sequence of any one of SEQ ID NO: <NUM> to SEQ ID NO: <NUM>.

As used herein, the term "ornithine-based product" refers to a material, which can be biosynthesized from ornithine as a precursor. Specifically, examples of the materials that can be produced by the ornithine cycle include putrescine, citrulline, proline, and arginine, as long as it can be biosynthesized from ornithine as a precursor. For example, the ornithine-based product may be putrescine and arginine. Additionally, any material, which can be synthesized from ornithine as a precursor and exported by the polypeptide having an ability to export an ornithine-based product of the present invention, may be used.

Another aspect of the present invention provides a polynucleotide encoding the polypeptide of the present invention having an ability to export an ornithine-based product.

The polynucleotide may include a polynucleotide encoding a polypeptide having an amino acid sequence of any one of SEQ ID NO: <NUM> to SEQ ID NO: <NUM>, or a polypeptide having a homology or identity thereto of <NUM>% or more, specifically <NUM>% or more, more specifically <NUM>% or more, even more specifically <NUM>% or more, even more specifically <NUM>% or more, and even more specifically <NUM>% or more, can be used, as long as it has an activity similar to the polypeptide having an ability to export an ornithine-based product. Additionally, it is apparent that due to codon degeneracy, polynucleotides, which can be translated into the protein consisting of the amino acid sequence of SEQ ID NO: <NUM> or proteins having a homology or identity thereto can also be used. Alternatively, a probe, which can be prepared from a known gene sequence, for example, any sequence, which hybridizes with a sequence complementary to all or part of the nucleotide sequence under stringent conditions to encode a protein having the activity of the protein consisting of the amino acid sequence of SEQ ID NO: <NUM>, can be used. The sequence having a homology or identity may exclude a sequence having a homology of <NUM>% within the range above, or may be a sequence having a homology of less than <NUM>%.

The "stringent conditions" refer to conditions, under which specific hybridization between polynucleotides is allowed. Such conditions are specifically disclosed in the literature (e.g., J. Sambrook et al. For example, the stringent conditions may include conditions under which genes having a high homology or identity, a homology or identity of <NUM>% or more, specifically <NUM>% or more, more specifically <NUM>% or more, even more specifically <NUM>% or more, even more specifically <NUM>% or more, and even more specifically <NUM>% or more, hybridize with each other, while genes having a homology or identity lower than the above homology or identity do not hybridize with each other; or may include ordinary washing conditions of Southern hybridization, i.e., washing once, specifically two or three times, at a salt concentration and a temperature corresponding to <NUM>, <NUM>×SSC, and <NUM>% SDS; specifically <NUM>, <NUM>×SSC, and <NUM>% SDS; and more specifically <NUM>, <NUM>×SSC, and <NUM>% SDS.

Hybridization requires that two nucleic acids have complementary sequences, although mismatches between bases are possible depending on the stringency of the hybridization. The term "complementary" is used to describe the relationship between nucleotide bases that can hybridize with each other. For example, with respect to DNA, adenosine is complementary to thymine, and cytosine is complementary to guanine. Therefore, an isolated nucleic acid fragment complementary to the entire sequence as well as a nucleic acid sequence substantially similar thereto can also be used.

Specifically, the polynucleotide having homology may be detected using hybridization conditions including a hybridization step at a Tm value of <NUM> under the above-described conditions. Additionally, the Tm value may be <NUM>, <NUM>, or <NUM>, and may be appropriately controlled by those skilled in the art depending on the purpose thereof.

The appropriate stringency for hybridizing polynucleotides depends on the length and degree of complementarity of the polynucleotides, and these variables are well known in the art (Sambrook et al. , supra, <NUM>-<NUM>, <NUM>-<NUM>).

As used herein, the term "homology" refers to the degree of correspondence between two given amino acid sequences or nucleotide sequences, and may be expressed as a percentage. In the present invention, a homologous sequence having an activity, which is identical or similar to that of the given amino acid sequence or nucleotide sequence may be indicated in terms of "% homology".

As used herein, the term "identity" refers to the degree of relevance between two given amino acid sequences or nucleotide sequences. In some cases, the identity is determined by the correspondence between strings of such sequences.

The terms "homology" and "identity" are often used interchangeably with each other.

The sequence homology or identity of conserved polynucleotides or polypeptides may be determined by standard alignment algorithms and can be used together with default gap penalty established by the program being used. Substantially, homologous or identical polynucleotides or polypeptides are generally expected to hybridize to all or at least about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>% or about <NUM>% of the entire length of the target polynucleotides or polypeptides under moderate or high stringent conditions. Polynucleotides that contain degenerate codons instead of codons are also considered in the hybridizing polynucleotides.

Whether any two polynucleotide or polypeptide sequences have a homology or identity of at least <NUM>%, <NUM>%, <NUM>%, <NUM>% <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>% or <NUM>% with each other, it may be determined by a known computer algorithm such as the "FASTA" program (e.g., <NPL>) using default parameters. Alternatively, it may be determined by the Needleman-Wunsch algorithm (<NPL>), which is performed using the Needleman program of the EMBOSS package (<NPL>) (preferably, version <NUM>. <NUM> or versions thereafter) (GCG program package (<NPL>)), BLASTP, BLASTN, FASTA (<NPL>); <NPL>, and [<NPL>). For example, the homology or identity may be determined using BLAST or ClustalW of the National Center for Biotechnology Information (NCBI).

The homology or identity of polynucleotides or polypeptides may be determined by comparing sequence information using, for example, the GAP computer program, such as <NPL> as disclosed in <NPL>. In summary, the GAP program defines the homology or identity as the value obtained by dividing the number of similarly aligned symbols (i.e. nucleotides or amino acids) by the total number of the symbols in the shorter of the two sequences. Default parameters for the GAP program may include (<NUM>) a unary comparison matrix (containing a value of <NUM> for identities and <NUM> for non-identities) and the weighted comparison matrix of <NPL>, as disclosed in <NPL>; (<NUM>) a penalty of <NUM> for each gap and an additional <NUM> penalty for each symbol in each gap (or a gap opening penalty of <NUM> and a gap extension penalty of <NUM>); and (<NUM>) no penalty for end gaps. Accordingly, as used herein, the term "homology" or "identity" refers to the comparison between polypeptides or polynucleotides.

Still another aspect of the present invention provides a vector comprising the polynucleotide.

As used herein, the term "vector" refers to a DNA construct containing the nucleotide sequence of a polynucleotide encoding the target polypeptide, which is operably linked to a suitable regulatory sequence such that the target polypeptide can be expressed in an appropriate host. The regulatory sequence may include a promoter capable of initiating transcription, any operator sequence for the control of the transcription, a sequence encoding an appropriate mRNA ribosome-binding domain, and a sequence regulating the termination of transcription and translation. After being transformed into a suitable host cell, the vector may be replicated or function irrespective of the host genome, and may be integrated into the host genome itself.

The vector used in the present invention is not particularly limited as long as it can be replicated in a host cell, and any vector known in the art may be used. Examples of conventionally used vectors may include natural or recombinant plasmids, cosmids, viruses, and bacteriophages. For example, as a phage vector or cosmid vector, pWE15, M13, MBL3, MBL4, IXII, ASHII, APII, t10, t11, Charon4A, Charon21A, etc., may be used, and as a plasmid vector, those based on pBR, pUC, pBluescriptII, pGEM, pTZ, pCL, pET, etc. may be used. The vector that can be used in the present invention is not particularly limited, and a known expression vector may be used. Specifically, the vectors pDZ, pACYC177, pACYC184, pCL, pECCG117, pUC19, pBR322, pMW118, pCC1BAC, etc. may be used.

In an embodiment, a polynucleotide encoding a target polypeptide in the chromosome may be replaced with a modified polynucleotide through a vector for intracellular chromosome insertion. The insertion of the polynucleotide into the chromosome may be performed by any method known in the art, for example, homologous recombination.

As used herein, the term "transformation" refers to a process of introducing a vector comprising a polynucleotide encoding a target polypeptide into a host cell, thereby enabling expression of the polypeptide encoded by the polynucleotide in the host cell. As long as the transformed polynucleotide can be expressed in the host cell, it does not matter whether it is inserted into the chromosome of a host cell and located therein or located outside the chromosome, and both cases may be included. For example, the transformation may be carried out via electroporation, calcium phosphate (CaPO<NUM>) precipitation, calcium chloride (CaCl<NUM>) precipitation, microinjection, a polyethylene glycol (PEG) technique, a DEAE-dextran technique, a cationic liposome technique, a lithium acetate-DMSO technique, etc.. Additionally, the polynucleotide includes DNA and RNA, which encode a target polypeptide. The polynucleotide may be introduced in any form as long as it can be introduced into a host cell and expressed therein. For example, the polynucleotide may be introduced into a host cell in the form of an expression cassette, which is a gene construction including all elements necessary for self-expression. The expression cassette may conventionally include a promoter operably linked to the polynucleotide, a terminator, a ribosome-binding domain, and a stop codon. The expression cassette may be in the form of an expression vector capable of self-replication. Additionally, the polynucleotide may be introduced into a host cell as it is and operably linked to a sequence necessary for its expression in the host cell.

Further, as used above, the term "operably linked" refers to a functional linkage between the above gene sequence and a promoter sequence, which initiates and mediates the transcription of the polynucleotide encoding the target polypeptide of the present invention.

Still another aspect of the present invention provides a microorganism producing an ornithine-based product, comprising the polypeptide having an ability to export an ornithine-based product or having an enhanced activity of the polypeptide.

Specifically, the present invention provides a microorganism of the genus Corynebacterium producing putrescine or arginine, including the polypeptide having an ability to export an ornithine-based product or having an enhanced activity of the polypeptide.

As used herein, the term "microorganism" includes all of wild-type microorganisms, or naturally or artificially genetically modified microorganisms, and it may be a microorganism in which a particular mechanism is weakened or enhanced due to insertion of a foreign gene, or enhancement or inactivation of the activity of an endogenous gene.

As used herein, the term "microorganism of the genus Corynebacterium" may be specifically Corynebacterium glutamicum, Corynebacterium ammoniagenes, Brevibacterium lactofermentum, Brevibacterium flavum, Corynebacterium thermoaminogenes, Corynebacterium efficiens, etc.. More specifically, the microorganisms of the genus Corynebacterium in the present invention may be Corynebacterium glutamicum, the cell growth and survival of which are hardly affected even when exposed to a high concentration of putrescine or arginine.

As used herein, the term "microorganism of the genus Corynebacterium producing an ornithine-based product" refers to a microorganism of the genus Corynebacterium having an ability to produce an ornithine-based product naturally or via modification. The microorganism of the genus Corynebacterium producing an ornithine-based product may be those modified such that the activity of at least one selected from the group consisting of, for example, acetylglutamate synthase, which converts glutamate to N-acetylglutamate, or ornithine acetyltransferase (argJ), which converts N-acetylornithine to ornithine, acetylglutamate kinase (ArgB), which converts N-acetylglutamate to N-acetylglutamyl phosphate, acetyl-gamma-glutamyl-phosphate reductase (ArgC), which converts N-acetylglutamyl phosphate to N-acetylglutamate semialdehyde, and acetylornithine aminotransferase (ArgD), which converts N-acetylglutamate semialdehyde to N-acetylornithine is further enhanced compared to the endogenous activity thereof, in order to enhance the biosynthetic pathway from glutamate to ornithine, thereby improving ornithine productivity.

As used herein, the term "microorganism of the genus Corynebacterium producing putrescine or arginine" refers to a microorganism of the genus Corynebacterium having an ability to produce putrescine or arginine naturally or via modification. The microorganism of the genus Corynebacterium does not produce putrescine, can produce arginine, but the productivity of arginine is remarkably low. Therefore, as used herein, the microorganism of the genus Corynebacterium producing putrescine or arginine refers to a native strain itself or a microorganism of the genus Corynebacterium, in which a foreign gene involved in the putrescine or arginine production mechanism is inserted, or the activity of an endogenous gene is enhanced or weakened, so as to have an improved productivity of putrescine or arginine.

Additionally, the microorganism producing putrescine may be those further modified such that the activity of at least one selected from the group consisting of ornithine carbamoyltransferase (ArgF), which is involved in the synthesis of arginine from ornithine, a protein involved in glutamate export, and acetyltransferase, which acetylates putrescine, is further inactivated compared to the endogenous activity thereof, and/or may be those modified such that an ornithine decarboxylase (ODC) activity is introduced.

Further, the microorganism producing arginine may be those further modified such that the activity of at least one selected from the group consisting of ornithine carbamoyltransfrase, (ArgF), which is involved in the synthesis of arginine from ornithine, argininosuccinate synthase (argG), argininosuccinate lyase (argH), aspartate ammonia lyase, and aspartate aminotransferase is further increased, compared to the endogenous activity thereof.

As used herein, the term "enhancement" of activity of a protein means that the activity of a protein is introduced, or the activity is enhanced as compared with the endogenous activity thereof. The "introduction" of the activity means that the activity of a specific polypeptide that the microorganism did not originally have is naturally or artificially expressed.

As used herein, the term "increase" in the activity of a protein as compared with the endogenous activity thereof means that the activity of a protein is improved as compared with the endogenous activity of a protein possessed by a microorganism, or the activity of a non-modified protein before transformation. The "endogenous activity" refers to the activity of a specific protein originally possessed by the parental strain or a non-modified microorganism prior to transformation thereof, when the traits of the microorganism are altered through genetic modification due to natural or artificial factors, and it can be interchangeably used with the activity before transformation.

Specifically, the enhancement of activity in the present invention may be performed by the following methods:.

The increasing of the copy number of the polynucleotide in method <NUM>) above may be performed in the form in which the polynucleotide is operably linked to a vector, or by inserting into a chromosome of a host cell. Specifically, it may be performed by operably linking the polynucleotide encoding the protein of the present invention to a vector, which can replicate and function regardless of the host cell, and introducing the same into the host cell. Alternatively, it may be performed by a method for increasing the copy number of the polynucleotide in the chromosome of the host cell by operably linking the polynucleotide to a vector, which can insert the polynucleotide into the chromosome of the host cell, and introducing the same into the host cell.

Next, the modification of an expression regulatory sequence such that the expression of the polynucleotide is increased in method <NUM>) may be performed by inducing a modification in the sequence through deletion, insertion, or non-conservative or conservative substitution of a nucleic acid sequence, or a combination thereof so as to further enhance the activity of the expression regulatory sequence, or by replacing with a nucleic acid sequence having a stronger activity. Additionally, the expression regulatory sequence may include a promoter, an operator sequence, a sequence encoding a ribosome-binding domain, a sequence regulating the termination of transcription and translation, etc..

A strong heterologous promoter may be linked to the upstream region of the expression unit of the polynucleotide instead of the original promoter. Examples of the strong promoter include CJ7 promoter (<CIT> and International Publication No. <CIT>), lysCP1 promoter (International Publication No. <CIT>), EF-Tu promoter, groEL promoter, aceA or aceB promoter, etc.. Further, the modification of the polynucleotide sequence on a chromosome in method <NUM>) may be performed by inducing a modification in the expression regulatory sequence through deletion, insertion, or non-conservative or conservative substitution of a nucleic acid sequence, or a combination thereof so as to further enhance the activity of the polynucleotide sequence, or by replacing the polynucleotide sequence with a polynucleotide sequence modified to have a stronger activity.

Additionally, the introduction a foreign polynucleotide sequence in method <NUM>) may be performed by introducing into a host cell a foreign polynucleotide encoding a protein that exhibits an activity identical or similar to that of the protein above, or a modified polynucleotide in which the codons of the foreign polynucleotide have been optimized. The foreign polynucleotide may be used by its origin or sequence as long as it exhibits an activity identical or similar to that of the protein. Further, the foreign polynucleotide may be introduced into a host cell after optimization of its codons so as to achieve the optimized transcription and translation in the host cell. The introduction may be performed by those skilled in the art by selecting a suitable transformation method known in the art, and a protein can be produced as the introduced polynucleotides are expressed in the host cell, thereby increasing its activity.

Finally, the method for modification to enhance the activity by a combination of methods <NUM>) to <NUM>) in method <NUM>) may be performed by a combined application of at least one of the following methods: increasing the copy number of the polynucleotide encoding the protein, modifying an expression regulatory sequence such that the expression of the polynucleotide is increased, modifying the polynucleotide sequence on a chromosome, and modifying a foreign polynucleotide exhibiting the activity of the protein or a codon-optimized modified polynucleotide thereof.

As used herein, the term "inactivation" of the activity of a protein includes both reduction in activity due to weakening or having no activity at all, as compared to the endogenous activity thereof.

The inactivation of the activity of a protein may be achieved by various methods well known in the art. Examples of the methods include a method of deleting a part or the entirety of a gene encoding the protein on a chromosome, including the case where the activity of the protein is eliminated; a method of replacing the gene encoding the protein on the chromosome with a gene mutated so as to reduce the enzyme activity; a method of introducing a modification into an expression regulatory sequence of the gene encoding the protein on the chromosome; a method of replacing an expression regulatory sequence of the gene encoding the protein with a sequence having a weak activity or no activity (e.g., a method of replacing the gene promoter with a promoter weaker than the endogenous promoter); a method of deleting a part or the entirety of a gene encoding the protein on a chromosome; a method of introducing an antisense oligonucleotide that binds complementarily to the transcript of the gene on the chromosome to inhibit the translation of the mRNA into the protein (e.g., antisense RNA); a method of artificially adding a sequence complementary to the upstream of the SD sequence of the gene encoding the enzyme to form a secondary structure, thereby making the adhesion of ribosome impossible; and a method of reverse transcription engineering (RTE), which adds a promoter to the <NUM>' end of the open reading frame (ORF) of the corresponding sequence so as to be reverse-transcribed, or a combination thereof.

Specifically, the method of deleting a part or the entirety of a gene encoding the protein may be performed by replacing the polynucleotide encoding the endogenous target protein within the chromosome with a polynucleotide having a partially deleted nucleic acid sequence or a marker gene through a vector for chromosomal insertion into microorganisms. In an embodiment, a method for deleting a gene by homologous recombination may be used. Additionally, as used herein, the term "part", although it may vary depending on the kinds of polynucleotide and may be appropriately selected by those skilled in the art, may specifically refer to <NUM> to <NUM> nucleotides, more specifically <NUM> to <NUM> nucleotides, and even more specifically <NUM> to <NUM> nucleotides.

Additionally, the method of modifying an expression regulatory sequence may be performed by inducing a modification in the expression regulatory sequence through deletion, insertion, conservative or non-conservative substitution, or a combination thereof so as to further weaken the activity of the expression regulatory sequence; or by replacing the sequence with a nucleic acid sequence having a weaker activity. The expression regulatory sequence may include a promoter, an operator sequence, a sequence encoding a ribosome-binding domain, and a sequence regulating the termination of transcription and translation.

Further, the method of modifying the gene sequence on the chromosome may be performed by inducing a modification in the gene sequence through deletion, insertion, conservative or non-conservative substitution, or a combination thereof so as to further inactivate the activity of the protein; or by replacing the sequence with a gene sequence modified to further inactivate the activity, or a gene sequence modified to have no activity at all.

Still another aspect of the present invention provides a method for producing an ornithine-based product, comprising:.

In a specific embodiment, the present invention provides a method for producing putrescine, comprising:.

In another specific embodiment, the present invention provides a method for producing L-arginine, comprising:.

The polypeptide having an ability to export an ornithine-base product and/or the microorganism producing an ornithine-based product are as described above.

In the method above, the culturing of the microorganism may be performed by a known batch culture method, continuous culture method, fed-batch culture method, etc.. In particular, with respect to the culture conditions, the pH of the culture may be adjusted to a suitable pH (e.g., pH <NUM> to <NUM>, specifically pH <NUM> to <NUM>, and most specifically pH <NUM>) using a basic compound (e.g., sodium hydroxide, potassium hydroxide, or ammonia) or an acidic compound (e.g., phosphoric acid or sulfuric acid). Additionally, oxygen or oxygen-containing gas mixture may be injected into the culture in order to maintain an aerobic state. The culture temperature may be maintained at <NUM> to <NUM>, specifically at <NUM> to <NUM>, and the culturing may be performed for about <NUM> hours to <NUM> hours. The putrescine produced by the culture may be secreted in the medium or may remain in the cells.

Additionally, as a carbon source for the culture medium to be used, sugars and carbohydrates (e. , glucose, sucrose, lactose, fructose, maltose, molasses, starch, and cellulose), oils and fats (e.g., soybean oil, sunflower seed oil, peanut oil, and coconut oil), fatty acids (e.g., palmitic acid, stearic acid, and linoleic acid), alcohols (e.g., glycerol and ethanol), organic acids (e.g., acetic acid), etc. may be used alone or in combination. As a nitrogen source, nitrogen-containing organic compounds (e.g., peptone, yeast extract, meat gravy, malt extract, corn steep liquor, soybean flour, and urea) or inorganic compounds (e.g., ammonium sulfate, ammonium chloride, ammonium phosphate, ammonium carbonate, and ammonium nitrate), etc. may be used alone or in combination. As a phosphorus source, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, corresponding sodium-containing salts thereof, etc. may be used alone or in combination. In addition, essential growth-promoting materials such as other metal salts (e.g., magnesium sulfate or iron sulfate), amino acids, vitamins, etc. may be contained in the medium.

In the method for recovering the ornithine-based product produced in the culturing step of the present invention, the desired products may be collected from the cultured microorganism or medium using an appropriate method known in the art. For example, centrifugation, filtration, anion-exchange chromatography, crystallization, HPLC, etc. may be used. Additionally, the method for recovering the ornithine-based product may further include a purification process using an appropriate method known in the art.

The present invention will be described in more detail through exemplary embodiments.

It has been found that NCgl2522, a gene of Corynebacterium glutamicum, has an ability to export putrescine (<CIT>). To this end, the following experiment was conducted to confirm whether NCgl2522 can also export citrulline, proline, and arginine, which can be biosynthesized from ornithine as a starting material, in addition to putrescine.

Specifically, it was confirmed whether NCgl2522 has an ability to export arginine as a representative example, among the products that can be biosynthesized from ornithine as a starting material.

In order to enhance the NCgl2522 activity in the wild-type ATCC21831 strain and KCCM10741P (<CIT>) having an arginine-producing ability, the CJ7 promoter (<CIT>) was introduced to the upstream of the initiation codon of NCgl2522 within the chromosome.

A homologous recombinant fragment, which includes the CJ7 promoter disclosed in <CIT> and in which both ends of the promoter have the original NCgl2522 sequence on the chromosome, was obtained. Specifically, the <NUM>'-end region of the CJ7 promoter was obtained by performing PCR using a primer pair of SEQ ID NOS: <NUM> and <NUM> shown in Table <NUM>, based on the genomic DNA of the Corynebacterium glutamicum ATCC21831 or KCCM10741P as a template. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> seconds. Additionally, the CJ7 promoter region was obtained by performing PCR under the same conditions using a primer pair of SEQ ID NOS: <NUM> and <NUM> shown in Table <NUM>, and the <NUM>'-end region of the CJ7 promoter was obtained by performing PCR using a primer pair of SEQ ID NOS: <NUM> and <NUM> under the same conditions, based on the genomic DNA of the Corynebacterium glutamicum ATCC21831 or KCCM10741P as a template. The primers used in the substitution of promoters are shown in Table <NUM> below.

Each of the PCR products obtained above was subjected to fusion cloning into the pDZ vector treated with BamHI and XbaI. The fusion cloning was performed at <NUM> for <NUM> minutes using the In-Fusion® HD Cloning Kit (Clontech Laboratories, Inc. ), and the thus-obtained plasmids were named pDZ-P(CJ7)-NCgl2522-<NUM> and pDZ-P(CJ7)-NCgl2522-10741P, respectively.

The plasmids pDZ-P(CJ7)-NCgl2522-<NUM> and pDZ-P(CJ7)-NCgl2522-10741P prepared above were respectively introduced into ATCC21831 and KCCM10741P, which are arginine-producing strains, via electroporation to obtain transformants, and the thus-obtained transformants were plated on BHIS plate media (<NUM>/L of brain heart infusion, <NUM>/L of sorbitol, and <NUM>% agar) containing kanamycin (<NUM>µg/mL) and X-gal (<NUM>-bromo-<NUM>-chloro-<NUM>-indolin-D-galactoside) and cultured to form colonies. Among the thus-formed colonies, the strains introduced with the plasmid pDZ-P(CJ7)-NCgl2522-<NUM> or pDZ-P(CJ7)-NCgl2522-10741P were selected.

The selected strains were cultured with shaking (<NUM>, <NUM> hours) in CM media (<NUM>/L of glucose, <NUM>/L of polypeptone, <NUM>/L of yeast extract, <NUM>/L of beef extract, <NUM>/L of NaCl, and <NUM>/L of urea at pH <NUM>) and sequentially diluted from <NUM>-<NUM> to <NUM>-<NUM>, plated on solid media containing X-gal, and cultured to form colonies. Among the thus-formed colonies, white colonies, which appeared at a relatively low rate were selected, thereby finally selecting the strains, in which the promoter of the NCgl2522 gene was substituted with the CJ7 promoter by a secondary crossover. The finally selected strains were subjected to PCR using a primer pair of SEQ ID NOS: <NUM> and <NUM> shown in Table <NUM>, and the thus-obtained products were applied to sequencing. As a result, it was confirmed that the CJ7 promoter was introduced into the upstream of the initiation codon of NCgl2522 within the chromosome. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> minute.

The thus-selected modified strains of Corynebacterium glutamicum were named ATCC21831_Pcj7 Ncgl2522 and KCCM10741P_Pcj7 NCgl2522, respectively.

In order to confirm the effect of the NCgl2522 gene on the ability to export arginine, one of the ornithine-based products, the arginine-producing ability was compared among the modified strains of Corynebacterium glutamicum ATCC21831_Pcj7 Ncgl2522 and KCCM10741P _Pcj7 NCgl2522 prepared in Example <NUM> above.

As the control groups, Corynebacterium glutamicum ATCC21831 and KCCM10741P, which are the parent strains, were used, and one platinum loop of each strain was inoculated into a <NUM>-mL corner-baffled flask containing <NUM> of production media [<NUM>% glucose , <NUM>% ammonium sulfate, <NUM>% monopotassium phosphate, <NUM>% magnesium sulfate heptahydrate, <NUM>% corn steep liquor (CSL), <NUM>% NaCl, <NUM>% yeast extract, and <NUM>µg/L of biotin at pH <NUM>] and cultured at <NUM> at a rate of <NUM> rpm for <NUM> hours to produce arginine. After completion of the culture, the arginine production was measured by HPLC.

As shown in Table <NUM>, when the promoter of the NCgl2522 gene in KCCM10741P and ATCC21831 was enhanced by substitution with the CJ7 promoter, the modified strains of Corynebacterium glutamicum showed an increase in the arginine production by <NUM>% and <NUM>% as compared to the parent strains, respectively. Additionally, it was confirmed that the concentration of ornithine, a reactant before conversion to arginine, was also increased in the modified strains as compared to the parent strains.

Based on these findings, it was confirmed that the NCgl2522 gene is not only a gene for exporting putrescine, but also has an ability to export products including ornithine, which are biosynthesized from ornithine as a starting material. Additionally, it can be interpreted from the above results that the NCgl2522 gene and the variants of the present invention can be very useful in the production of ornithine-based products using biomass.

In order to increase the activity of the ornithine-based product-exporting protein, the present inventors constructed variants for NCgl2522 (<CIT>), a gene encoding the putrescine-exporting protein.

Specifically, in order to construct a library of the NCgl2522 gene variants, a random mutagenesis PCR (JENA error-prone PCR) was performed using a specific primer pair of SEQ ID NOS: <NUM> and <NUM> excluding the initiation codon of ORF of the NCgl2522 gene shown in Table <NUM>, based on the genomic DNA of Corynebacterium glutamicum ATCC13032 as a template.

The thus-prepared mutant gene fragments were subjected to fusion cloning into the pDZ vector cleaved with XbaI. The fusion cloning was performed at <NUM>° C for <NUM> minutes using the In-Fusion® HD Cloning Kit (Clontech Laboratories, Inc. ), thereby completing the construction of plasmid libraries of pDZ-N2522 variants.

The thus-constructed recombinant plasmid libraries were screened via high throughput screening (HTS). In particular, the platform strain used for screening was KCCM11240P, which is a Corynebacterium glutamicum-derived recombinant microorganism capable of producing putrescine (<CIT>).

Specifically, in order to obtain variants with an improved activity for exporting putrescine, the thus-constructed plasmid libraries were introduced into KCCM11240P via electroporation to obtain transformants, and the thus-obtained transformants were plated on BHIS plate media (<NUM>/L of brain heart infusion, <NUM>/L of sorbitol, and <NUM>% agar) containing kanamycin (<NUM>µg/mL) and X-gal (<NUM>-bromo-<NUM>-chloro-<NUM>-indolin-D-galactoside) and cultured to form colonies. Among the thus-formed colonies, the strains introduced with the plasmid pDZ-N2522 variant libraries were selected.

The selected strains were cultured by shaking in a <NUM> deep well plate along with titer media (<NUM>/L of glucose, <NUM>/L of MgSO<NUM>·<NUM><NUM>O, <NUM>/L of MgCl<NUM>, <NUM>/L of KH<NUM>PO<NUM>, <NUM>/L of (NH<NUM>)<NUM>SO<NUM>, <NUM>/L of soybean protein hydrolysate, <NUM>/L of MnSO<NUM>·<NUM><NUM>O, <NUM>µg/L of thiamine HCl, <NUM>µg/L of biotin, <NUM>/L of FeSO<NUM>·<NUM><NUM>O, <NUM> arginine, and <NUM>µg/mL of kanamycin at pH <NUM>), and the concentration of putrescine produced in each culture was measured, and then one transformant with the greatest increase in putrescine productivity compared to the control was selected. Subsequently, it was confirmed as to which modification was induced in the amino acid sequence of the NCgl2522 protein for the selected transformant. The sequence of the Ncgl2522 variant was confirmed as follows: a homologous recombinant fragment was obtained by performing colony PCR using a primer pair of SEQ ID NOS: <NUM> and <NUM>, based on the transformant including the corresponding variants, followed by applying the product to genome sequencing using a primer of SEQ ID NO: <NUM>. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> minute.

As a result, it was confirmed that the selected NCgl2522 variant was modified such that the alanine (Ala), which is the amino acid residue at position <NUM> from the N-terminus of the NCgl2522 amino acid sequence (SEQ ID NO: <NUM>) of Corynebacterium glutamicum ATCC13032 was substituted with serine (Ser), and was named NCgl2522_M1 (SEQ ID NO: <NUM>).

Based on the NCgl2522_M1 variant prepared in Example <NUM>, the present inventors realized that the amino acid residue at position <NUM> from the N-terminus is important for the activity of the NCgl2522 protein. Accordingly, various variants, in which the amino acid residue at position <NUM> of the NCgl2522 protein was substituted with other amino acid residues, were prepared.

Specifically, a homologous recombinant fragment was obtained using a specific primer pair of SEQ ID NOS: <NUM> and <NUM> excluding the initiation codon of ORF of NCgl2522 gene, based on the genomic DNA of Corynebacterium glutamicum ATCC13032 as a template. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> seconds.

Subsequently, the PCR product obtained above was subjected to fusion cloning into the pDZ vector treated with XbaI. The fusion cloning was performed using the In-Fusion® HD Cloning Kit (Clontech Laboratories, Inc. ), and the thus-obtained plasmid was named pDZ-NCgl2522_A152.

Then, in order to induce a random mutagenesis on the amino acid residue at position <NUM> of NCgl2522, a plasmid library for the pDZ-NCgl2522_A152 variant was completed by performing PCR using a primer pair of SEQ ID NOS: <NUM> and <NUM> shown in Table <NUM>, based on the plasmid pDZ-NCgl2522_A152 constructed above as a template. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> minutes.

The thus-constructed recombinant plasmid libraries were screened via high throughput screening (HTS). In particular, the platform strain used for screening was KCCM11240P, which is a Corynebacterium glutamicum-derived recombinant microorganism capable of producing putrescine.

The constructed plasmid libraries were introduced into KCCM11240P via electroporation to obtain transformants, and the strains introduced with the plasmid pDZ-NCgl2522_A152 variant were selected in the same manner as in Example <NUM>. Eight transformants with the greatest increase in putrescine productivity compared to the control group were selected, and it was confirmed as to which modifications were induced in the amino acid sequence of the NCgl2522 protein for each transformant, in the same manner as in Example <NUM>.

As a result, variants in which alanine, the amino acid residue at position <NUM> from the N-terminus of the NCgl2522 amino acid sequence (SEQ ID NO: <NUM>) of Corynebacterium glutamicum ATCC13032, was substituted with other amino acids, were confirmed. Among them, the variant, in which the amino acid residue at position <NUM> was substituted with asparagine, was named NCgl2522_M4 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with proline, was named NCgl2522_M5 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with lysine, was named NCgl2522_M6 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with glutamic acid, was named NCgl2522_M7 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with cysteine, was named NCgl2522_M8 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with glutamine, was named NCgl2522_M9 (SEQ ID NO: <NUM>), and the variant, in which the amino acid residue at position <NUM> was substituted with methionine, was named NCgl2522_M10 (SEQ ID NO: <NUM>).

Additionally, in order to confirm whether the effect of increasing putrescine productivity due to the modification can be applied to NCgl2522 proteins derived from different strains, various variants, in which the amino acid residue at position <NUM> of the NCgl2522 protein derived from Corynebacterium glutamicum ATCC13869 was substituted with other amino acid residues, were constructed.

Specifically, a homologous recombinant fragment was obtained using a specific primer pair of SEQ ID NOS: <NUM> and <NUM> excluding the initiation codon of ORF of NCgl2522 gene, based on the genomic DNA of Corynebacterium glutamicum ATCC13869 as a template. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> seconds.

The PCR product obtained above was subjected to fusion cloning into the pDZ vector treated with XbaI. The fusion cloning was performed using the In-Fusion® HD Cloning Kit (Clontech Laboratories, Inc. ), and the thus-obtained plasmid was named pDZ-<NUM>-NCgl2522_A152.

Then, in order to induce a random mutagenesis on the amino acid residue at position <NUM> of NCgl2522, a plasmid library for the pDZ-<NUM>-NCgl2522_A152 variant was completed by performing PCR using a primer pair of SEQ ID NOS: <NUM> and <NUM>, based on the plasmid pDZ-<NUM>-NCgl2522_A152 constructed above as a template. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> minutes.

Subsequently, the thus-constructed recombinant plasmid libraries were screened via high throughput screening (HTS). In particular, the platform strain used for screening was DAB <NUM>-b, which is a Corynebacterium glutamicum-derived recombinant microorganism capable of producing putrescine. Then, the constructed plasmid libraries were introduced into DAB <NUM>-b via electroporation to obtain transformants, and the strains introduced with the plasmid pDZ-<NUM>-NCgl2522_A152 variant were selected in the same manner as in Example <NUM>.

As a result, nine variants, in which the amino acid residue at position <NUM> from the N-terminus of the NCgl2522 amino acid sequence (SEQ ID NO: <NUM>) of Corynebacterium glutamicum ATCC13869 was substituted, were selected, as the NCgl2522 variants of Corynebacterium glutamicum ATCC13032. Among them, the variant in which alanine, the amino acid residue at position <NUM>, was substituted with serine was named NCgl2522_M2 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with asparagine, was named NCgl2522_M11 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with histidine, was named NCgl2522_M12 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with proline, was named NCgl2522_M13 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with lysine, was named NCgl2522_M14 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with glutamic acid, was named NCgl2522_M15 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with cysteine, was named NCgl2522_M16 (SEQ ID NO: <NUM>), the variant, in which the amino acid residue at position <NUM> was substituted with glutamine, was named NCgl2522_M17 (SEQ ID NO: <NUM>), and the variant, in which the amino acid residue at position <NUM> was substituted with methionine, was named NCgl2522_M18 (SEQ ID NO: <NUM>).

In order to increase the ability to export putrescine of the putrescine-producing strain, NCgl2522_M1, NCgl2522_M3, NCgl2522_M4, NCgl2522_M5, NCgl2522_M6, NCgl2522_M7, NCgl2522_M8, NCgl2522_M9 and NCgl2522_M10, which are variants of the NCgl2522 gene, were respectively introduced into the chromosome of the Corynebacterium glutamicum ATCC13032-based putrescine-producing strain.

Specifically, homologous recombinant fragments having a modified sequence of NCgl2522_M1, NCgl2522_M3, NCgl2522_M4, NCgl2522_M5, NCgl2522_M6, NCgl2522_M7, NCgl2522_M8, NCgl2522_M9, and NCgl2522_M10 were respectively obtained by performing PCR using primer pairs of SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, and SEQ ID NOS: <NUM> and <NUM> shown in Table <NUM>, based on the genomic DNA of Corynebacterium glutamicum ATCC13032 as a template. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> seconds.

Each of the PCR products obtained above was subjected to fusion cloning into the pDZ vector treated with XbaI. The fusion cloning was performed using the In-Fusion® HD Cloning Kit (Clontech Laboratories, Inc. ), and the thus-obtained plasmids were named pDZ-NCgl2522_M1, pDZ-NCgl2522_M3, pDZ-NCgl2522_M4, pDZ-NCgl2522_M5, pDZ-NCgl2522_M6, pDZ-NCgl2522_M7, pDZ-NCgl2522_M8, pDZ-NCgl2522_M9 and pDZ-NCgl2522_M10, respectively.

The plasmids pDZ-NCgl2522_M1, pDZ-NCgl2522_M3, pDZ-NCgl2522_M4, pDZ-NCgl2522_M5, pDZ-NCgl2522_M6, pDZ-NCgl2522_M7, pDZ-NCgl2522_M8, pDZ-NCgl2522_M9 and pDZ-NCgl2522_M10 prepared above were respectively introduced into KCCM11240P (<CIT>), which is a Corynebacterium glutamicum ATCC13032-based putrescine-producing strain, via electroporation to obtain transformants, and the thus-obtained transformants were plated on BHIS plate media (<NUM>/L of brain heart infusion, <NUM>/L of sorbitol, and <NUM>% agar) containing kanamycin (<NUM>µg/mL) and X-gal (<NUM>-bromo-<NUM>-chloro-<NUM>-indolin-D-galactoside) and cultured to form colonies. Among the thus-formed colonies, the strains introduced with each plasmid were selected.

Each of the strains selected above was cultured with shaking (<NUM>, <NUM> hours) in CM media (<NUM>/L of glucose, <NUM>/L of polypeptone, <NUM>/L of yeast extract, <NUM>/L of beef extract, <NUM>/L of NaCl, and <NUM>/L of urea at pH <NUM>) and sequentially diluted from <NUM>-<NUM> to <NUM>-<NUM>, plated on solid media containing X-gal, and cultured to form colonies. Among the thus-formed colonies, white colonies, which appeared at a relatively low rate were selected, thereby finally selecting the strains, in which the NCgl2522 gene was substituted with each of the variants by a secondary crossover. The finally selected strains were subjected to PCR using a primer pair of SEQ ID NOS: <NUM> and <NUM>, and the thus-obtained products were applied to sequencing to confirm the substitution with each of the variants. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> minute.

The thus-selected modified strains of Corynebacterium glutamicum were named KCCM11240P NCgl2522_M1, KCCM11240P NCgl2522_M3, KCCM11240P NCgl2522_M4, KCCM11240P NCgl2522_M5, KCCM11240P NCgl2522_M6, KCCM11240P NCgl2522_M7, KCCM11240P NCgl2522_M8, KCCM11240P NCgl2522_M9 and KCCM11240P NCgl2522_M10, respectively.

DAB12-a ΔNCgl1469 (<CIT>), which is a Corynebacterium glutamicum ATCC13869-based putrescine-producing strain, was named DAB12-b. To this end, in order to increase the ability to export putrescine of the putrescine-producing strain, NCgl2522_M2, NCgl2522_M11, NCgl2522_M12, NCgl2522_M13, NCgl2522_M14, NCgl2522_M15, NCgl2522_M16, NCgl2522_M17 and NCgl2522_M18, which are variants of the NCgl2522 gene, were respectively introduced into the chromosome of the DAB12-b strain.

Specifically, homologous recombinant fragments having a modified sequence of NCgl2522_M2, NCgl2522_M11, NCgl2522_M12, NCgl2522_M13, NCgl2522_M14, NCgl2522_M15, NCgl2522_M16, NCgl2522_M17 and NCgl2522_M18 were respectively obtained by performing PCR using primer pairs of SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, SEQ ID NOS: <NUM> and <NUM>, and SEQ ID NOS: <NUM> and <NUM> shown in Tables <NUM> and <NUM>, based on the genomic DNA of Corynebacterium glutamicum ATCC13869 as a template. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> seconds.

Each of the PCR products obtained above was subjected to fusion cloning into the pDZ vector treated with XbaI. The fusion cloning was performed using the In-Fusion® HD Cloning Kit (Clontech Laboratories, Inc. ), and the thus-obtained plasmids were named pDZ-NCgl2522_M2, pDZ-NCgl2522_M11, pDZ-NCgl2522_M12, pDZ-NCgl2522_M13, pDZ-NCgl2522_M14, pDZ-NCgl2522_M15, pDZ-NCgl2522_M16, pDZ-NCgl2522_M17, and pDZ-NCgl2522_M18, respectively.

Each of the plasmids prepared above was introduced into DAB12-b via electroporation to obtain transformants, and the thus-obtained transformants were plated on BHIS plate media (<NUM>/L of brain heart infusion, <NUM>/L of sorbitol, and <NUM>% agar) containing kanamycin (<NUM>µg/mL) and X-gal (<NUM>-bromo-<NUM>-chloro-<NUM>-indolin-D-galactoside) and cultured to form colonies. Among the thus-formed colonies, the strains introduced with the above plasmids were selected.

Each of the strains selected above was cultured with shaking (<NUM>, <NUM> hours) in CM media (<NUM>/L of glucose, <NUM>/L of polypeptone, <NUM>/L of yeast extract, <NUM>/L of beef extract, <NUM>/L of NaCl, and <NUM>/L of urea at pH <NUM>) and sequentially diluted from <NUM>-<NUM> to <NUM>-<NUM>, plated on solid media containing X-gal, and cultured to form colonies. Among the thus-formed colonies, white colonies, which appeared at a relatively low rate were selected, thereby finally selecting the strains, in which the NCgl2522 gene was substituted each of the variants by a secondary crossover. The finally selected strains were subjected to PCR using a primer pair of SEQ ID NOS: <NUM> and <NUM>, and the thus-obtained products were applied to sequencing to confirm the substitution with the variants. In particular, the PCR reaction was performed by repeating <NUM> cycles of denaturation at <NUM> for <NUM> seconds, annealing at <NUM> for <NUM> seconds, and extension at <NUM> for <NUM> minute.

The thus-selected modified strains of Corynebacterium glutamicum were named DAB12-b NCgl2522_M2, DAB12-b NCgl2522_M11, DAB12-b NCgl2522_M12, DAB12-b NCgl2522 _M13, DAB12-b NCgl2522_M14, DAB12-b NCgl2522_M15, DAB12-b NCgl2522_M16, DAB12-b NCgl2522_M17, and DAB12-b NCgl2522_M18, respectively.

In order to confirm the effect of NCgl2522 variants on putrescine production when the variants of NCgl2522 gene, which increases the ability to export putrescine, were introduced into the putrescine-producing strains, the putrescine-producing ability was compared among the modified strains of Corynebacterium glutamicum prepared in Examples <NUM>-<NUM> and <NUM>-<NUM>.

Specifically, the modified strains of Corynebacterium glutamicum (KCCM11240P NCgl2522_M1; KCCM11240P NCgl2522_M3; KCCM11240P NCgl2522_M4; KCCM11240P NCgl2522_M5; KCCM11240P NCgl2522_M6; KCCM11240P NCgl2522_M7; KCCM11240P NCgl2522_M8; KCCM11240P NCgl2522_M9; KCCM11240P NCgl2522_M10; DAB12-b NCgl2522_M2; DAB12-b NCgl2522_M11; DAB12-b NCgl2522_M12; DAB12-b NCgl2522_M13; DAB12-b NCgl2522_M14; DAB12-b NCgl2522_M15; DAB12-b NCgl2522_M116; DAB12-b NCgl2522_M17; and DAB12-b NCgl2522_M18) and two kinds of parent strains (KCCM11240P and DAB12-b) were respectively plated on <NUM> arginine-containing CM plate media (<NUM>% glucose, <NUM>% polypeptone, <NUM>% yeast extract, <NUM>% beef extract, <NUM>% NaCl, <NUM>% urea, <NUM>µL of <NUM>% NaOH, and <NUM>% agar at pH <NUM>, based on <NUM>), and cultured at <NUM> for <NUM> hours. About one platinum loop of each strain cultured therefrom was inoculated into <NUM> of titer media (<NUM>% glucose, <NUM>% soybean protein, <NUM>% corn steep solids, <NUM>% (NH<NUM>)<NUM>SO<NUM>, <NUM>% KH<NUM>PO<NUM>, <NUM>% MgSO<NUM>. <NUM><NUM>O, <NUM>% urea, <NUM>µg of biotin, <NUM> of thiamine HCl, <NUM> of calcium-pantothenic acid, <NUM> of nicotinamide, and <NUM>% CaCO<NUM>, based on <NUM>), and cultured with shaking at <NUM> at a rate of <NUM> rpm for <NUM> hours. During culturing of all strains, <NUM> arginine was added to the media. After completion of the culture, the concentration of putrescine produced in each culture was measured, and the results are shown in Table <NUM> below.

As shown in Table <NUM> above, when each of the variants was introduced into KCCM11240P, all of the nine modified strains of Corynebacterium glutamicum showed an increase in the putrescine production and productivity compared to the parent strains by <NUM>% to <NUM>%. Additionally, when each of the variants was introduced into DAB12-b, all of the nine modified strains of Corynebacterium glutamicum showed an increase in the putrescine production and productivity compared to the parent strains by <NUM>% to <NUM>%. In particular, the productivity represents the putrescine production per hour for each transformant, and was expressed in g/L/h.

In order to so confirm the effect of the variants of NCgl2522 gene, NCgl2522_M1, NCgl2522_M3, NCgl2522_M4, NCgl2522_M5, NCgl2522_M6, NCgl2522_M7, NCgl2522_M8, NCgl2522_M9, and NCgl2522_M10 were respectively introduced into the chromosome of KCCM11240P P(CJ7)-NCgl2522 (<CIT>), which is a Corynebacterium glutamicum ATCC13032-based putrescine-producing strain with an increased ability to export putrescine.

Specifically, each of the plasmids pDZ-NCgl2522_M1, pDZ-NCgl2522_M3, pDZ-NCgl2522_M4, pDZ-NCgl2522_M5, pDZ-NCgl2522_M6, pDZ-NCgl2522_M7, pDZ-NCgl2522_M8, pDZ-NCgl2522_M9, pDZ-NCgl2522_M10 prepared in Example <NUM>-<NUM> was transformed into KCCM11240P P(CJ7)-NCgl2522 in the same manner as in Example <NUM>-<NUM>, and thus it was confirmed that the NCgl2522 gene was substituted with the variants within the chromosome thereof. The selected modified strains of Corynebacterium glutamicum were named KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M1, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M3, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M4, KCCM11240P P(CJ7)-NCgl2522 NCgl2522M5, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M6, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M7, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M8, KCCM11240P P(CJ7)-NCgl2522 NCgl2522M9, and KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M10, respectively.

In order to confirm the effect of NCgl2522 variants on the Corynebacterium glutamicum producing strains with an improved ability to export putrescine, the putrescine-producing ability was compared among the modified strains of Corynebacterium glutamicum prepared in Example <NUM>-<NUM> and the parent strain.

Specifically, the modified strains of Corynebacterium glutamicum (KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M1, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M3, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M4, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M5, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M6, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M7, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M8, KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M9, and KCCM11240P P(CJ7)-NCgl2522 NCgl2522_M10) and the parent strain (KCCM11240P P(CJ7)-NCgl2522) were respectively plated on <NUM> arginine-containing CM plate media (<NUM>% glucose, <NUM>% polypeptone, <NUM>% yeast extract, <NUM>% beef extract, <NUM>% NaCl, <NUM>% urea, <NUM>µL of <NUM>% NaOH, and <NUM>% agar at pH <NUM>, based on <NUM>), and cultured at <NUM> for <NUM> hours. About one platinum loop of each strain cultured therefrom was inoculated into <NUM> of titer media (<NUM>% glucose, <NUM>% soybean protein, <NUM>% corn steep solids, <NUM>% (NH<NUM>)<NUM>SO<NUM>, <NUM>% KH<NUM>PO<NUM>, <NUM>% MgSO<NUM>. <NUM><NUM>O, <NUM>% urea, <NUM>µg of biotin, <NUM> of thiamine HCl, <NUM> of calcium-pantothenic acid, <NUM> of nicotinamide, and <NUM>% CaCO<NUM>, based on <NUM>), and cultured with shaking at <NUM> at a rate of <NUM> rpm for <NUM> hours. During culturing of all strains, <NUM> arginine was added to the media. After completion of the culture, the concentration of putrescine produced in each culture was measured, and the results are shown in Table <NUM> below.

As shown in Table <NUM> above, when the nine variants were respectively introduced into KCCM11240P P(CJ7)-NCgl2522 with an improved ability to export putrescine, the modified strains of Corynebacterium glutamicum showed an increase in the putrescine production and productivity by <NUM>% to <NUM>% compared to the parent strain, which already showed an improved ability to export putrescine. In particular, the productivity represents the putrescine production per hour for each transformant, and was expressed in g/L/h.

In order to increase the ability to export L-arginine of the L-arginine-producing strain, NCgl2522_M1, NCgl2522_M3, NCgl2522_M4, NCgl2522_M5, NCgl2522_M6, NCgl2522_M7, NCgl2522_M8, NCgl2522_M9 and NCgl2522_M10, which are variants of NCgl2522 gene, were respectively introduced into the chromosome of Corynebacterium glutamicum KCCM10741P (<CIT>).

Specifically, PCR was performed using primer pairs shown in Table <NUM> based on the genomic DNA of Corynebacterium glutamicum KCCM10741P as a template, in the same manner as in Example <NUM>-<NUM>, and the strains, in which the NCgl2522 gene was substituted with NCgl2522_M1, NCgl2522_M3, NCgl2522_M4, NCgl2522_M5, NCgl2522_M6, NCgl2522_M7, NCgl2522_M8, NCgl2522_M9 or NCgl2522_M10, were finally selected.

The modified strains of Corynebacterium glutamicum selected therefrom were named KCCM10741P NCgl2522_M1, KCCM10741P NCgl2522_M3, KCCM10741P NCgl2522_M4, KCCM10741P NCgl2522_M5, KCCM10741P NCgl2522_M6, KCCM10741P NCgl2522_M7, KCCM10741P NCgl2522_M8, KCCM10741P NCgl2522_M9 and KCCM10741P NCgl2522_M10, respectively.

In order to increase the ability to export L-arginine of the wild-type Corynebacterium glutamicum ATCC21831-based L-arginine-producing strain, NCgl2522_M2, NCgl2522_M11, NCgl2522_M12, NCgl2522_M13, NCgl2522M14, NCgl2522_M15, NCgl2522_M16, NCgl2522_M17 and NCgl2522_M18, which are variants of NCgl2522 gene, were respectively introduced into the chromosome of ATCC21831.

Specifically, PCR was performed using primer pairs shown in Table <NUM> based on the genomic DNA of Corynebacterium glutamicum ATCC21831 as a template, in the same manner as in Example <NUM>-<NUM>, and the strains, in which the NCgl2522 gene was substituted with NCgl2522_M2, NCgl2522_M11, NCgl2522_M12, NCgl2522_M13, NCgl2522_M14, NCgl2522_M15, NCgl2522_M16, NCgl2522_M17 and NCgl2522_M18, were finally selected.

The modified strains of Corynebacterium glutamicum selected therefrom were named ATCC21831 NCgl2522_M2, ATCC21831 NCgl2522_M11, ATCC21831 NCgl2522_M12, ATCC21831 NCgl2522_M13, ATCC21831 NCgl2522_M14, ATCC21831 NCgl2522_M15, ATCC21831 NCgl2522_M16, ATCC21831 NCgl2522_M17, and ATCC21831 NCgl2522_M18, respectively.

In order to confirm the effect of NCgl2522 variants on L-arginine production when the variants of NCgl2522 gene, which increases the ability to export L-arginine, were introduced into the L-arginine-producing strains, the L-arginine-producing ability was compared among the modified strains of Corynebacterium glutamicum prepared in Examples <NUM>-<NUM> and <NUM>-<NUM>.

In particular, as the control groups, the Corynebacterium glutamicum KCCM10741P and ATCC21831, which are the parent strains, and KCCM10741P_Pcj7 Ncgl2522 and ATCC21831_Pcj7 Ncgl2522, which were prepared in Example <NUM>, were used. One platinum loop of each strain was inoculated into a <NUM>-mL corner-baffled flask containing <NUM> of production media [<NUM>% glucose, <NUM>% ammonium sulfate, <NUM>% monopotassium phosphate, <NUM>% magnesium sulfate heptahydrate, <NUM>% corn steep liquor (CSL), <NUM>% NaCl, <NUM>% yeast extract, and <NUM>µg/L of biotin at pH <NUM>] and cultured with shaking at <NUM> at a rate of <NUM> rpm for <NUM> hours to produce L-arginine. After completion of the culture, the L-arginine production was measured by HPLC.

As shown in Table <NUM>, when each variant was introduced into KCCM10741P, all of the modified strains of Corynebacterium glutamicum introduced with the variants showed an increase in the L-arginine production by <NUM>% and <NUM>% as compared to the parent strains. Additionally, when each variant was introduced into ATCC21831, all of the nine modified strains of Corynebacterium glutamicum showed an increase in the L-arginine production by <NUM>% and <NUM>% as compared to the parent strains.

Further, it was confirmed that the concentration of L-ornithine, which was exported after conversion into L-arginine, also increased when the variants were introduced. Based on these findings, it can be interpreted that the modified strains of Corynebacterium glutamicum may also export products biosynthesized from ornithine as a starting material.

In conclusion, the present inventors have confirmed that the amino acid residue at position <NUM> from the N-terminus plays a key role in the ability to export ornithine-based products in NCgl2522, a putrescine-exporting protein. In particular, when the amino acid at position <NUM> was substituted with other amino acid residues, it was found that the production of the ornithine-based products was increased in the strains introduced with the variants. Accordingly, the variants of the present invention can be applied to a method for producing ornithine-based products using microorganisms to further improve the production thereof, and thus can be very useful for the production of ornithine-based products using biomass.

Claim 1:
A polypeptide having an ability to export an ornithine-based product, wherein the alanine residue at position <NUM> from the N-terminus of the amino acid sequence of an ornithine-based product-exporting protein, which consists of an amino acid sequence of SEQ ID NO: <NUM> or SEQ ID NO: <NUM>, is substituted with other amino acids.