bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of two dioxygenases from Pseudomonas putida
Authors: Lee Y L , Dagley S
Published: January 2020

Catechol 2,3-dioxygenase and homoprotocatechuate 2,3-dioxygenase were purified from the same strain of Pseudomonas putida. Molecular weights and subunit sizes were similar, but amino acid compositions showed some marked differences.
Induction of the acetamidase of Aspergillus nidulans by acetate metabolism
Authors: Hynes M J
Published: January 2020

Growth tests and enzyme determinations strongly suggest that the acetamidase of Aspergillus nidulans is induced by a product of acetate metabolism rather than the substrate, acetamide. The cis-dominant mutation, amdI9, which is closely linked to amdS, the structural gene for the acetamidase, results in greatly increased sensitivity to induction by acetate metabolism. Propionate, L-threonine, and ethanol also result in acetamidase induction. Mutations in the facA, facB, and facC genes, which lead to low levels of acetyl-coenzyme A synthase, are epistatic to the amdI9 mutation for strong growth on acetamide medium and abolish acetamide and propionamide induction of the acetamidase and isocitrate lyase enzymes. Acetate, L-threonine, and ethanol, however, can induce these enzymes in strains containing facA and facC lesions but not in strains containing a facB lesion. The evidence suggests that acetamidase and isocitrate lyase may be induced by a similar mechanism.
Tetrapyrrole utilization by Bacteroids ruminocola
Authors: McCall D R , Caldwell D R
Published: January 2020

Reduced versus oxidized difference spectra of whole cells and pyridine hemochromogens of heme-requiring isolates of Bacteroides ruminicola are altered when deuteroporphyrin or mesoporphyrin replaces protoheme as a growth factor. During growth in the presence of either deuteroporphyrin or mesoporphyrin, whole cells exhibit peaks at 545 t547, 515 to 518, and 412 to 413 nm. Pyridine hemochromogen spectra confirm the presence of meso -or deuteroheme in cells grown in the presence of meso- or deuteroporphyrin. No evidence was found for the conversion of either meso- or deuteroporphyrin to protoheme. Cells grown in the presence of the manganese of magnesium chelates of protoheme form iron-containing hemes. Neither spontaneous decomposition of noniron metalloporphyrin chelates nor spontaneous formation of hemes from Fe2+ and metal-free porphyrins was detected. Protoheme-synthesizing isolates of B. ruminicola fail to use preformed metal-free porphyrins, but form both protoheme- and deuteroheme-containing cytochromes when grown in the presence of manganese deuteroheme. Versatility in tetrapyrrole utilization by B. ruminicola appears to reflect the ability of the organism to mediate the removal of nonferrous ions and to insert Fe2+ into the tetrapyrrole nucleus. The orgamism also forms functional b-type cytochromes with prosthetic groups other than protoheme.
Cyclic adenosine 3',5'-monophosphate regulation of membrane energetics in Escherichia coli
Authors: Dills S E , Dobrogosz W J
Published: January 2020

Mutants of Escherichia coli K-12 lacking functional adenylate cyclase (cya) or the cyclic adenosine 3',5'-monophosphate (cAMP) receptor protein (crp) were compared with their wild type to evaluate the role played by the cAMP-cAMP receptor protein complex in regulating this organism's membrane-associated bioenergetic functions. Both mutants were found to be equally defective in carrying out various electron transport activities. In particular, their capacity for synthesizing a functional oxygen-linked transhydrogenase system was totally repressed, and their content of flavin adenine dinucleotide was reduced by approximately 85%. In addition, it was found that the mutant strains had a decreased ability to generate a protonmotive force and to use this chemiosmotic force to generate adenosine 5'-triphosphate. All these membrane-associated dysfunctions were completely restored to the wild-type state when the cya cells were grown in the presence of exogenous cAMP. As would be expected if these controls were operating at the transcriptional level, the crp cells retained the mutant character even when grown in the presence of this cyclic nucleotide.
In vitro production of bacitracin by proteolysis of vegetative Bacillus licheniformis cell protein
Authors: Vitković L , Sadoff H L
Published: January 2020

The action of a sporulation-specific seryl protease on antibiotic-free extracts of Bacillus licheniformis cells yields a peptide that is identified as bacitracin by its biological activity, its spectral properties, and its comigration with genuine bacitracin in both paper and thin-layer chromatography. During proteolysis, a chemical structure is generated with the spectral properties of a delta-2 thiazoline ring. The yield in vitro, 4 microgram of bacitracin per mg of protein, is less than the maximal yield from sporulating cells, 75 microgram of bacitracin per mg of cell protein, but is a linear function of the amount of protein in the reaction system. Approximately 30% of the protein yielding the antibiotic is ribosomal associated, and only 25% of that amount can be removed by washing with 1 M NH4Cl. The substrate protein is a constant fraction of the cell protein throughout exponential growth and very early sporulation stages of culture development.
Characterization of a novel thiosulfate-forming enzyme isolated from Desulfovibrio vulgaris
Authors: Drake H L , Akagi J M
Published: January 2020

An enzyme that formed thiosulfate from bisulfite and trithionate was purified from extracts of Desulfovibrio vulgaris. This enzyme, designated as "thiosulfate-forming" enzyme, required the presence of both bisulfite and trithionate. Various 35S-labeling studies showed that thiosulfate was formed from bisulfite and the inner sulfur atom of trithionate. This involved a nucleophilic attack by the bisulfite ion, resulting in the displacement of the two outer sulfonate groups of trithionate that recycled to participate as free bisulfite in subsequent reactions. This reaction required a reduction, presumably by a concerted mechanism with thiosulfate formation. The natural electron carrier cytochrome c3 participated in this reductive formation of thiosulfate. This reaction was coupled to the bisulfite reductase-catalyzed reaction, which resulted in the reconstruction of a thiosulfate-forming pathway from bisulfite.
Effect of Urea Concentration on Growth of
Ureaplasma urealyticum
(T-Strain Mycoplasma)
Authors: Kenny George E. , Cartwright Frank D.
Published: January 2020

The effect of urea on growth of
Ureaplasma urealyticum
type VIII was studied by cultivating the organisms in a dialysate broth, prepared from soy peptone and autoclaved yeast, supplemented with 5% dialyzed horse serum, 100 mM 2-(
N
-morpholino)ethane sulfonic acid buffer (pH 5.75), and defined amounts of urea. Without urea, growth did not occur. Total growth was directly related to urea concentration. The least amount of urea that supported growth was 0.032 mM, which resulted in 3 × 10
4
colony-forming units per ml. The maximum yield of organisms, 8.0 × 10
7
colony-forming units per ml, was observed at 32 mM urea. Growth was limited not only by urea concentration, but also by the buffer capacity of the medium. The maximum amount of 2-(
N
-morpholino)ethane sulfonic acid buffer that could be employed was 100 mM; at higher concentrations, growth was inhibited. The yield of
U. urealyticum
was small even in medium with 32 mM urea and 100 mM 2-(
N
-morpholino)ethane sulfonic acid buffer: 0.63 mg of protein per liter of culture containing 5 × 10
10
total colony-forming units. The molar growth yield was 20 mg of protein per mol of urea. The growth rate was also a function of urea concentration. Generation times ranged from 8 h at 0.032 mM urea to 1.6 h at 3.2 mM urea, where the substrate level was saturating. The

K
s

value for growth was 2.0 × 10
−4
M urea. Thus, urea is a growth-limiting factor for
U. urealyticum
, but remarkably large amounts of this substrate are required.
Mercury and Organomercurial Resistances Determined by Plasmids in
Staphylococcus aureus
Authors: Weiss Alison A. , Murphy Sandra D. , Silver Simon
Published: January 2020

Penicillinase plasmids of
Staphylococcus aureus
often contain genes conferring resistance to inorganic mercury (Hg
2+
) and the organomercurial phenylmercury acetate. The mechanism of resistance was found to be the enzymatic hydrolysis of the organomercurial phenylmercury to benzene plus inorganic ionic mercury, which was then enzymatically reduced to metallic mercury (Hg
0
). The Hg
0
was rapidly volatilized from the medium into the atmosphere. After the mercurial was degraded and the mercury was volatilized, the resistant cells were able to grow. These plasmids also conferred the ability to volatilize mercury from thimerosal, although the plasmid-bearing strains were equally as thimerosal sensitive as the
S. aureus
without plasmids. None of the plasmids conferred the ability to volatilize mercury from several other organomercurials, however: methylmercury, ethylmercury,
p
-hydroxymercuribenzoate, merbromin, and fluorescein mercuric acetate. (Organomercurial resistance-conferring plasmids of
Escherichia coli
and
Pseudomonas aeruginosa
that we have been studying confer the ability to degrade two or three of these organomercurials.) Although mercury was not volatilized from
p
-hydroxymercuribenzoate or fluorescein mercuric acetate, the plasmid-bearing strains were resistant to these organomercurials. The ability to volatilize mercury from Hg
2+
and phenylmercury was inducible. The range of inducers included Hg
2+
, phenylmercury, and several organomercurials that were not substrates for the degradation system. Mercury-sensitive mutants have been isolated from the parental plasmids pI258 and pII147. Thirty-one such mercury-sensitive strains fall into three classes: (i) mercury-sensitive strains totally devoid of the phenylmercury hydrolase and Hg
2+
reductase activities; (ii) mutants with normal hydrolase levels and no detectable reductase; and (iii) mutants with essentially normal hydrolase levels and low and variable (5 to 25%) levels of reductase activities. The mercury-sensitive strains were also sensitive to phenylmercury, including those with the potential for hydrolase activity.
Tryptophan-transducing bacteriophages: in vitro studies with restriction endonucleases HindII + III and Escherichia coli ribonucleic acid polymerase
Authors: Jones B B , Reznikoff W S
Published: January 2020

The HindII + III restriction enzyme fragmentation pattern of various lambda-phi80trp deoxyribonucleic acid molecules is presented. An analysis of deoxyribonucleic acid molecules carrying deletions ending within the trp regulatory elements and a deoxyribonucleic acid molecule carrying a deletion within trpE indicates that a fragment of 8.3 X 10(5) daltons contains at least part of the trp promoter, the entire trp leader region, and part of the trpE gene. The observation that ribonucleic acid polymerase, when present in the HindII + III digestion mixture, results in the fusion of this 8.3 X 10(5)-dalton fragment to the preceding bacterial fragment suggests that HindII + III cuts within trpP.
Intracellular localization and effects on cell division of a plasmid blocked in deoxyribonucleic acid replication
Authors: MacQueen H A , Donachie W D
Published: January 2020

Cell division in a uvr mutant of Escherichia coli is suppressed by introdcution into the cell of an ultraviolet-irradiated plasmid. Autoradiography was used to determine the localization of the incoming plasmid and the segregation pattern of the host chromosomes.
Reconstitution and purification of flagellar filaments from Caulobacter crescentus
Authors: Sheffery M , Newton A
Published: January 2020

Filaments from isolated flagella of Caulobacter crescentus have been purified by successive dissociation and reconstitution. After the second and third reconstitutions from subunits in 0.8 M sodium citrate, filament preparations contained only two proteins, flagellin A (26,000 daltons) and flagellin B (28,000 daltons). There was some enrichment for flagellin A during reconstitution by this procedure, since isolated flagella contained flagellin A and flagellin B in a ratio of approximately 3.8:1 and filaments after the third reconstitution contained the two proteins in a ratio of 5.0:1.
Germination-defective mutant of Neurospora crassa that responds to siderophores
Authors: Charlang G , Williams N P
Published: January 2020

A conditionally germination-defective mutant of Neurospora crassa has been found to be partially curable by ferricrocin and other siderophores. The mutant conidia rapidly lose their membrane-bound siderophores when suspended in buffer or growth media. Germination is consequently delayed unless large numbers of conidia are present (positive population effect). This indicates that the mutant has a membrane defect involving the siderophore attachment site.
Repair and subsequent fragmentation of deoxyribonucleic acid in ultraviolet-irradiated Bacillus subtilis recA
Authors: Hadden C T
Published: January 2020

Cells of Bacillus subtilis recA1 are sensitive to irradiation with ultraviolet light. Evidence is presented here that these cells are not defective in ultraviolet light-induced incision of deoxyribonucleic acid (DNA) or repair DNA synthesis. Ligation of DNA at repair sites appears to occur, but the DNA is subsequently fragmented, apparently at sites of previous repair synthesis. It is hypothesized that the defect in DNA repair leads to host-specific restriction at repaired sites because of a defect in either the structure of the repaired region or specificity of the restriction/modification system.
Membrane Asymmetry and Expression of Cell Surface Antigens of
Micrococcus lysodeikticus
Established by Crossed Immunoelectrophoresis
Authors: Owen Peter , Salton Milton R. J.
Published: January 2020

Crossed immunoelectrophoresis of Triton X-100-solubilized plasma membranes of
Micrococcus lysodeikticus
established the presence of 27 discrete antigens. Individual antigens were identified as membrane components possessing enzyme activity by zymogram staining procedures and by reactivity of certain antigens with a selection of four lectins in the crossed-immunoelectrophoresis (immunoaffinoelectrophoresis) system. Absorption experiments with intact, stable protoplasts and isolated membranes established the asymmetric nature of the
M. lysodeikticus
plasma membranes. Of the 14 antigens with determinants accessible solely on the cytoplasmic face of the membrane, four possessed individual dehydrogenase activities, and a fifth was identifiable as a component possessing adenosine triphosphatase (EC 3.6.1.3) activity. Evidence from absorption studies with isolated membranes suggested that antigens such as the adenosine triphosphatase complex were more readily accessible to reaction with antibodies than was succinate dehydrogenase (EC 1.3.99.1), for example. Twelve antigens were located on the protoplast surface as determined by antibody absorption, and the succinylated lipomannan was identified as a major antigen. At least five other antigens possessed sugar residues that interacted with concanavalin A. With the antisera generated to isolated membranes, there was no evidence suggesting that any of these antigens was not detectable on either surface of the plasma membrane. From absorption experiments with washed, whole cells of
M. lysodeikticus
, it was concluded that the immunogens on the protoplast surface were also detectable on the surface of the intact cell. However, some of the components such as the succinylated lipomannan appeared to be exposed to a greater extent than others. The cytoplasmic fraction from
M. lysodeikticus
was used as an antigen source to generate antibodies, and 97 immunoprecipitates were resolvable by crossed immunoelectrophoresis. In the cytoplasm-anticytoplasm reference immunoelectrophoresis pattern of precipitates, three of the immunoprecipitates unique to the cytoplasmic fraction were identifiable by zymogram staining procedures as catalase (EC 1.11.1.6), isocitrate dehydrogenase (EC 1.1.1.42), and polynucleotide phosphorylase (EC 2.3.7.8). The identification of membrane and cytoplasmic antigens (including the above-mentioned enzymes) provides a sensitive analytical system for monitoring cross-contamination and antigen distribution in cellular fractions.
Generation of miniplasmids from copy number mutants of the R plasmid NR1
Authors: Taylor D P , Greenberg J , Rownd R H
Published: January 2020

Small, closed circular deoxyribonucleic acid molecules, called miniplasmids, were observed in Escherichia coli harboring copy number mutants of the R plasmid NR1 after growth in medium containing tetracycline. The level of tetracycline resistance conferred by the copy mutant plasmids was lower (3 to 6 microgram/ml) than that conferred by NR1 (100 MICROGRAM/ML). The presence of the miniplasmid enhanced the level of tetracycline resistance conferred by the copy mutant. Miniplasmids of molecular weights 4 X 10(6) to 13 X 10(6) were found. They carried no antibiotic resistance markers and could be eliminated by growth in the presence of chloramphenicol and/or streptomycin-spectinomycin. Studies with the restriction endonucleases EcoRI and Sal I indicated that the miniplasmids are derived from the region of the copy mutant plasmids that contains the origin for replication of the resistance transfer factor. There were approximately 12 copies of the miniplasmid per chromosome, compared with 3 and 6 copies of the copy mutants of NR1. The miniplasmids appeared to be incompatible with the copy mutant plasmids.
Genetics of Treponema: relationship between Treponema pallidum and five cultivable treponemes
Authors: Miao R , Fieldsteel A H
Published: January 2020

Three genetically distinct groups of treponemes have been identified by saturation reassociation assays using 125I-labeled treponemal DNAs. The three groups are (i) virulent Treponema pallidum (Nichols strain), (ii) T. phagedenis and its biotypes Reiter and Kazan 5, and (iii) T. refringens biotypes Nichols and Noguchi. There is no detectable DNA sequence homology (less than 5%) among the three groups. The groups have distinct guanine + cytosine contents: 52.4 to 53.7% for T. pallidum, 41.5% for T. refringens, and 38 to 39% for T. phagedenis.
Regulatory properties of araC(c) mutants in the L-arabinose operon of escherichia coliB/r
Authors: MacInnes K R , Sheppard D E , Falgout B
Published: January 2020

Merodiploids containing a high-constitutive and a low-constitutive araC(c) allele were assayed for constitutive expression of the ara operon. Low-constitutive araC(c) alleles either were unable to repress the constitutive rate of ara operon expression exhibited by by high-constitutive araC(c) alleles or achieved a partial repression of the high-constitutive rate of operon expression. Either mutation to a low-constitutive araC(c) mutant resulted in a partial or complete loss of repressor function, or subunit mixing between the two araC(c) mutant proteins resulted in a partial or complete dominance of the high-constitutive araC(c) allele. Five of the six araC(c) alleles tested allowed a partial induction of the ara operon in cya crp background. In general, a higher level of ara operon induction was achieved in the cya crp background by high araC(c) alleles than by low araC(c) alleles. Furthermore, several araC(c) mutants exhibited decreased sensitivity to catabolite repression, particularly in the presence of inducer. The results suggest a model in which certain araC(c) gene products can achieve ara operon induction in the presence of either arabinose (inducer) or catabolite activator protein-cyclic adenosine monophosphate, whereas the wild-type araC gene product requires the presence of both of these factors for operon expression.
Immunochemical analysis of inner and outer membranes of Escherichia coli by crossed immunoelectrophoresis
Authors: Smyth C J , Siegel J , Salton M R , Owen P
Published: January 2020

Isolated membrane fractions of Escherichia coli K-12 yielded complex immunoprecipitate patterns when Triton X-100 and sodium dodecyl sulfate extracts were examined by crossed immunoelectrophoresis with antienvelope immunoglobulins. Twelve of the 46 antigens in the immunoprecipitate patterns of inner (plasma) membranes were identified by zymograms and/or by the use of specific antisera. The following enzyme activities were detected in immunoprecipitates: 6-phosphogluconate dehydrogenase (EC 1.1.1.43); adenosine triphosphatase (EC 3.6.1.3); glutamate dehydrogenase (EC 1.4.1.4), two separate components; malate dehydrogenase (EC 1.1.1.37); dihydroorotate dehydrogenase (EC 1.3.3.1); succinate dehydrogenase (EC 1.3.99.1); lactate dehydrogeanse (EC 1.1.1.27); reduced nicotinamide adenine dinucleotide dehydrogenase (EC 1.6.99.3); protease (EC 3.4.21.1); and glycerol 3-phosphate dehydrogenase (EC 1.1.99.5). The corresponding immunoprecipitate pattern for isolated outer membranes consisted of at least 25 discrete antigens and differed strikingly from that obtained with inner membranes. Two major immunogens were identified as lipopolysaccharide and Braun lipoprotein. A protease-active immunoprecipitate was also detected in this fraction, but attempts to identify the Rosenbusch matrix protein in the crossed immunoelectrophoretic profile were unsuccessful.
Characterization of a Bacillus cereus protease mutant defective in an early stage of spore germination
Authors: Cheng Y S , Fitz-James P , Aronson A I
Published: January 2020

Temperature-sensitive sporulation mutants of Bacillus cereus were screened for intracellular protease activity that was more heat labile than that of the parental strain. One mutant grew as well as the wild type at 30 and 37 degrees C but sporulated poorly at 37 degrees C in an enriched or minimal medium. These spores germinated very slowly in response to alanine plus adenosine or calcium dipicolinate. During germination, spores produced by the mutant rapidly became heat sensitive, but released dipicolonic acid and mucopeptide fragments more slowly than the wild type and decreased only partially in density while remaining phase white (semirefractile). In freeze-etch electron micrographs, the mature spores were deficient in the outer cross-patched coat layer. During germination, the spore coat changes associated with wild-type germination occurred very slowly in this mutant. Although the original mutant was also a pyrimidine auxotroph, reversion to prototrophy did not alter any of the phenotypic properties discussed. Selection of revertants that germinated rapidly or sporulated well at 37 degrees C, however, resulted in restoratin of all wild-type properties (exclusive of the pyrimidine requirement) including heat-stable protease activity. The reversion frequency was consistent with an initial point mutation, indicating that a protease alteration resulted in production of spores defective in a very early stage of germination.
Purification and preliminary characterization of an aggregation-sensitive chemoattractant of Dictyostelium minutum
Authors: Kakebeeke P I , Mato J M , Konijn T M
Published: January 2020

Aggregative amoebae of Dictyostelium minutum are not attracted by cyclic AMP; they are sensitive to various attracting sources from which yeast extract was chosen to purify the chemoattractant. A small acrasin-like species-specific molecule which contains glycine and C5H5N5 has been purified 30,000-fold. Several characteristics of this chemotactic molecule, which is inactivated by an enzyme that is not species specific, are described.
Purification and properties of nitroalkane oxidase from Fusarium oxysporum
Authors: Kido T , Hashizume K , Soda K
Published: January 2020

A nitroalkane-oxidizing enzyme, which was inducibly formed by addition of nitroethane to the medium was purified to homogeneity from an extract of Fusarium oxysporum (IFO 5942) with an overall yield of about 20%. The enzyme catalyzed the oxidative denitrification of 1-nitropropane as follows: CH2(NO2)CH2CH3 + O2 + H2O leads to OHCCH2CH3 + HNO2 + H2O2. In addition to 1-nitropropane, 3-nitro-2-pentanol, 2-nitropropane, and nitrocyclohexane are good substrates; the enzyme is designated "nitroalkane oxidase" (EC class 1.7.3). The enzyme has a molecular weight of approximately 185,000 and consists of four subunits identical in molecular weight (47,000). Flavin adenine dinucleotide was required for the enzyme activity and could be replaced in part by riboflavin 5'-phosphate. The maximum reactivity was found at about pH 8.0. The enzyme was inhibited significantly by HgCl2, KCN, p-chloromercuribenzoate, and N-ethylmaleimide. The Michaelis constants are as follows: 1-nitropropane, 1.54 mM; 2-nitropropane, 7.40 mM; nitroethane, 1.00 mM; 3-nitro-2-pentanol, 3.08 mM; nitrocyclohexane, 0.90 mM; and flavin adenine dinucleotide, 1.33 micrometer.
Structural features of normal and complemented forms of the Neurospora isopropylmalate isomerase
Authors: Reichenbecher V E , Gross S R
Published: January 2020

The isopropylmalate isomerase (EC 4.2.1.33) of Neurospora crassa is a globular protein consisting of a single polypeptide chain with a molecular weight of about 90,000. The isomerase cannot easily be freed of a contaminating protease which cleaves the enzyme into two major fragments, one of approximately 56,000 and the other 37,000 daltons. This suggests that the folded polypeptide chain may contain some hinge point or loop exposed on the surface which makes it susceptible to proteolytic attack. Most of the isomerase activity extracted from the wild-type strain is in monomer form. However, a small fraction of the activity in crude extracts is found in multimeric aggregates, and the active isomerase extracted from complementing leu-2 heterokaryons consists entirely of dimers and higher multimers. These observations suggest that, though active as a monomer, a significant fraction of the normal enzyme might be organized in multimeric form within the cell.
Genetic analysis of antibiotic resistance in Streptococcus pyogenes
Authors: Stuart J G , Ferretti J J
Published: January 2020

The genetics of antibiotic resistance in mutant strains of Streptococcus pyrogenes was studied. Utilizing a type 6 strain (9440) primarily resistant to strepttomycin (Strr), classes of mutant strains were isolated that were resistant to one of the following antibiotics: rifampin (Rifr), erythromycin (Eryr), thiostrepton (Tstr), spiramycin (Sprr), fusidic acid (Fusr), gramicidin (Grcr), ethidium bromide (Ebrr), kanamycin (Kanr), neomycin (Neor), oleandomycin (Oler), gentamicin (Genr), and novobiocin (Novr). Transduction experiments separated antibiotic resistance markers into two distinct groups: transducible markers, including Fusr, Bacr, Ksg+, Spcr, Eryr, Sprr, Rifr, Stlr, and Tstr (Bacr, Ksgr, Spcr, and Stlr refer to resistance to bacitracin, kasugamycin, spectinomycin, and streptolydigan, respectively), and nontransducible markers, including Grcr, Ebrr, Kanr, Neor, Oler, Genr, and Novr. By means of two- and three-point crosses, transducible markers (excluding tst) were located in three separate linkage groups. spr was found to be linked with ery and spc in the order spc-ery-spr, whereas in a separate linkage group the order was determined to be str-fus-bac-ksg. The third linkage group contained the rif and stl markers.
Bacteriocin and antibiotic resistance plasmids in Bacillus cereus and Bacillus subtilis
Authors: Bernhard K , Schrempf H , Goebel W
Published: January 2020

A number of plasmids have been isolated as covalently closed circular DNAs from strains of Bacillus cereus and B. subtilis. From 12 out of 15 strains of B. cereus, plasmids could be isolated. Most of the B. cereus strains contained two or more plasmids. Their molecular weights ranged from 1.6 X 10(6) to 105 X 10(6). Bacteriocin production could be attributed to a 45 X 10(6)-dalton plasmid (pBC7) from B. cereus DSM 336, and tetracycline resistance to a 2.8 X 10(6) plasmid (pBC16) from B. cereus GP7. Two streptomycin-resistant strains of B. subtilis harbored plasmids of 5.2 X 10(6) and 9 X 10(6), respectively, which were, however, not correlated with the antibiotic resistance. The plasmid carrying resistance to tetracycline, pBC16, which was originally isolated from B. cereus, could be subsequently transformed in B. subtilis, where it is stably maintained.
DNA replication pattern and cell wall growth in Escherichia coli PAT 84
Authors: Koppes L J , Overbeeke N , Nanninga N
Published: January 2020

An electron microscopic radioautographic study was made of tritiated thymidine incorporation into the genome of Escherichia coli PAT 84 and of tritiated meso-D,L-2,6-diaminopimelic acid (DAP) into the cell envelope. Pulse-labeled cells growing at 30 degrees C with a doubling time of 170 min were classified according to length by the method of agar filtration. Mathematical analysis of the length distribution led to the assumption of an exponential relation between length and time. A novel DNA replication pattern was found. Within the cell cycle DNA replication terminates at 70 min; then a gap follows of 64 min, after which DNA replication is initiated at 134 min. Thus, the C period is 106 min and the D period is 100 min. Cell constriction starts at 141 min and coincides with initiation of DNA replication. Detailed quantitative analysis of the [3H]thymidine grain frequency distribution allowed the distinction of three groups of cells. The first group incorporated no label, the second group an amount C, and the third group an amount 2 X C. The relative contribution of each group to a particular length class was determined. The data fitted very well into the DNA replication pattern. The same analysis was carried out on DAP pulse-labeled cells. Again, three groups of cells could be distinguished, and their relative contributions to each length class was determined. The group with the double amount of label was especially prominent at the end of the cell cycle. The emergence of this group might represent the acquisition of new lateral growth areas.
Interrelationships of isoacceptor phenylalanine tRNA species of Rhodopseudomonas sphaeroides
Authors: Razel A J , Gray E D
Published: January 2020

The phenylalanine tRNA of Rhodopseudomonas sphaeroides was fractionated on benzoylated diethylaminoethyl-cellulose into four isoaccepting species (tRNAPheI to IV). tRNAPheIII represented 80% of the total tRNAPhe in anaerobic, photosynthetically grown organisms, whereas in cultures grown aerobically for prolonged periods, tRNAPheII represented 80% of the total. In cultures adapting to aerobic growth, the addition of rifampin resulted in a tRNAPhe profile characteristic of anaerobic-photosynthetic conditions due to the conversion of tRNAPheII to tRNAPheIII. In fully adapted aerobic cultures, this conversion was inhibited in the presence of chloramphenicol or rifampin. The conversion of tRNAPheIII to tRNAPheII was not observable in vivo. It is proposed that an enzymic activity synthesized during anaerobic-photosynthetic growth was responsible for the conversion.
Isolation and characterization of mutants of the plasmid pKM101 deficient in their ability to enhance mutagenesis and repair
Authors: Walker G C
Published: January 2020

A screening procedure was developed for identifying mutants of the plasmid pKM101 no longer capable of enhancing mutagenesis. The test was based on the large pKM101-mediated increase in the number of Gal+ papillae observed on colonies of Salmonella typhimurium gal mutants plated on tetrazolium-galactose plates in the presence of a mutagen. The pKM101 mutant plasmids transferred normally, were stably maintained in cells, caused normal levels of ampicillin resistance, and still imparted sensitivity to phage Ike to their hosts. However, the pKM101 mutants had lost the ability to (i) enhance the reversion of both point and frameshift mutations, (ii) protect the cells against killing by UV irradiation, (iii) increase the spontaneous reversion rates of point mutations, (iv) enhance plasmid-mediated reactivation of UV-irradiated phage P22, (v) enhance Weigle reactivation. One pKM101 mutant with different properties from the others was identified by its increased spontaneous mutator effect. It is suggested that pKM101 amplifies the activity of the inducible error-prone repair systems in bacteria and that this is the function of pKM101 in the Ames Salmonella tester strains used for detection of carcinogens as mutagens.
Growth, luminescence, respiration, and the ATP pool during autoinduction in Beneckea harveyi
Authors: Ulitzur S , Hastings J W
Published: January 2020

The bacterial bioluminescence system is unusual because it is self-induced. In the late logarithmic phase of growth, upon the accumulation of an autoinducer, the synthesis of the components of the system is initiated. We were interested in determining what effect this burst of synthesis and activity has on cellular energy metabolism. The ATP pool of the luminous bacterium Beneckea harveyi was found to dip 10- to 20-fold during the luminescence period, while the respiration per unit cell mass (optical density) increased but by much less. The dip in the ATP pool did not occur in four different types of dark mutants, including one that was temperature conditional and another that was conditional upon added cyclic AMP for luminescence. However, it is neither the synthesis nor the activity of luciferase that is responsible for the ATP dip; the dip does not occur in certain dark "aldehyde" mutants which nevertheless synthesize normal levels of luciferase, whereas it does occur at 36 degrees C in a temperature-sensitive luciferase mutant which forms normal levels of inactive luciferase. Results with other aldehyde mutants implicate the pathway involved in the synthesis of the aldehyde factor with the ATP dip.
In vitro synthesis of cystathionine gamma-synthetase in Escherichia coli K-12
Authors: Krueger J H , Johnson J R , Greene R C
Published: January 2020

Synthesis of cystathionine gamma-synthetase directed by DNA from a lambdadmet transducing phage has been achieved in cell extracts from Escherichia coli K-12. Enzyme synthesis was stimulated two- to threefold by the addition of guanosine 3'-diphosphate 5'-diphosphate to the incubation mixtures. Kinetic studies showed a 1.5- to 2.0-min lag between initiation of transcription and completion of a translatable message. This lag is shorter than that observed for beta-galactosidase synthesis with DNA from a lac transducing phage known to initiate transcription at the lac promoter. This result, together with information on the structure of the transducing phage, shows that pL is not used for initiation of in vitro metB transcription. Attempts to demonstrate repression were not successful, and unexpectedly, extracts from metJ+ strains were found to be more effective at enzyme synthesis than those from their metJ derivatives.
Inhibition of
Escherichia coli
Division by Protein X
Authors: Satta Giuseppe , Pardee Arthur B.
Published: January 2020

We propose that protein X provides the connection between damage to
Escherichia coli
DNA and inhibition of septation and cell division. This connection is needed to guarantee that each new bacterium receives a complete DNA copy. We present several new experiments here which demonstrate that the degree to which septation is inhibited following damage to DNA is correlated with the amount of protein X that is produced. Rifampin selectively blocks protein X production. This drug was shown to allow cells whose DNA had been damaged by nalidixic acid to resume septation. Several mutants formed septa-less filaments and also produced protein X at 42°C; rifampin both inhibited their production of protein X and permitted them to form septa and divide. Essentially complementary results were obtained with a
dnaA
mutant which at 42°C stopped making DNA, did not produce protein X, and continued to divide; added bleomycin degraded DNA, induced protein X, and inhibited septation. These results, as well as previous observations, are all consistent with the proposal that protein X is produced as a consequence of DNA damage and is an inhibitor of septation. We suggest that septation could require binding of a single-stranded region of DNA to a septum site in the membrane. Protein X could block this binding by combining with the DNA. This control could provide an emergency mechanism in addition to the usually proposed coordination in which completion of DNA synthesis creates a positive effector for a terminal step of septation. Or it could be the sole coordinating mechanism, even under unperturbed growth conditions.
Role of Na+ and Li+ in thiomethylgalactoside transport by the melibiose transport system of Escherichia coli
Authors: Lopilato J , Tsuchiya T , Wilson T H
Published: January 2020

Thiomethyl-beta-galactoside (TMG) accumulation via the melibiose transport system was studied in lactose transport-negative strains of Escherichia coli. TMG uptake by either intact cells or membrane vesicles was markedly stimulated by Na+ or Li+ between pH 5.5 and 8. The Km for uptake of TMG was approximately 0.2 mM at an external Na+ concentration of 5 mM (pH 7). The alpha-galactosides, melibiose, methyl-alpha-galactoside, and o-nitrophenyl-alpha-galactoside had a high affinity for this system whereas lactose, maltose and glucose had none. Evidence is presented for Li+-TMG or Na+-TMG cotransport.
Deoxyuridine residues in DNA of thymine-requiring Bacillus subtilis strains with defective N-glycosidase activity for uracil-containing DNA
Authors: Makino F , Munakata N
Published: January 2020

DNA extracted from exponentially growing cells of thymine-requiring Bacillus subtilis strains with defective N-glycosidase activity for deoxyuridine residues in DNA was subjected to the action of N-glycosidase in vitro and analyzed by sedimentation in alkaline sucrose gradients. The sites attacked by N-glycosidase occurred once per 6 X 10(6) to 7 X 10(6) daltons of DNA from cells cultured in the presence of growth-supporting concentrations of thymine. The number of N-glycosidase-susceptible sites increased when the thymine concentration in the medium was lowered. Parallel to this observation, the N-glycosidase-defective mutant cells were less apt to show the detrimental effect due to thymine depletion than were the parental cells. Such sites were not detected in DNA from cells with a normal N-glycosidase activity or with a "wild type" capacity for thymidylate synthesis. The results are interpreted to mean that cells defective for thymidylate synthesis incorporate dUTP in place of TTP in DNA and that the deoxyuridine residues, once incorporated, remain in the DNA in the absence of N-glycosidase activity.
Ribonucleoprotein particle appearing during sporulation in yeast
Authors: Wejksnora P J , Haber J E
Published: January 2020

During sporulation of Saccharomyces cerevisiae, most strains accumulate an unmethylated 20S RNA. Contrary to previous reports, this sporulation 20S RNA is distinct from the short-lived methylated 20S RNA precursor of 18S rRNA. This RNA species was found in a cytoplasmic 32S ribonucleoprotein particle consisting of one single-stranded 20S RNA molecule and 18 to 20 identical protein subunits of molecular weight 23,000. The ribonucleoprotein particle was resistant to ribonuclease digestion, although purified 20S RNA was ribonuclease sensitive. Both the RNA and the protein of the 32S ribonucleoprotein particle were only synthesized under conditions that induce sporulation. The accumulation of 20S RNA depended on continued protein synthesis but was actinomycin D insensitive, despite a high guanine-plus-cytosine content. Synthesis of 20S RNA stopped when cells were removed from sporulation conditions and placed in growth medium.
Purification and properties of 2-hydroxy-6-oxo-2,4-heptadienoate hydrolase from two strains of Pseudomonas putida
Authors: Bayly R C , di Berardino D
Published: January 2020

Growth on phenol of two strains of Pseudomonas putida biotype A, NCIB 10015 and NCIB 9865, elicits the synthesis of an enzyme that hydrolyzes 2-hydroxy-6-oxo-2,4-heptadienoate to 2-oxopent-4-enoate. The purified enzyme from Pseudomonas NCIB 10015 has a molecular weight of 118,000 and dissociates in sodium dodecyl sulfate to a species of molecular weight 27,700; the enzyme from Pseudomonas NCIB 9865 has a molecular weight of 100,000 and dissociates to a species of 25,000 molecular weight. The hydrolases from both strains have similar Km values, pH optima, and thermal labilities and attack the same range of substrates. Neither hydrolase was stimulated by Mg2+ or Mn2+, and both were inhibited by p-chloromercuribenzoate and iodoacetamide. Immunodiffusion studies with the purified enzymes and antibodies formed against them show some cross-reaction of Pseudomonas NCIB 9865 enzymes with antibodies to Pseudomonas NCIB 10015, but not vice versa.
Cleavage maps of a tetracycline plasmid from Staphylococcus aureus
Authors: Shafferman A , Shalita Z , Hertman I
Published: January 2020

The cleavage maps of a Staphylococcus aureus plasmid, pSN1 (2.75 megadaltons), conferring tetracycline resistance, were determined. Cleavage maps are given for HpaI and HindIII restriction endonucleases by using the single HpaII site as a reference point. Nucleases EcoRI, BamHI, SalI, and HaeIII have no sites on this plasmid.
Lipid and fatty acid composition of Gluconobacter oxydans before and after intracytoplasmic membrane formation
Authors: Heefner D L , Claus G W
Published: January 2020

Gluconobacter oxydans differentiates by forming quantities of intracytoplasmic membranes at the end of exponential growth, and this formation occurs concurrently with a 60% increase in cellular lipid. The present study was initiated to determine whether this newly synthesized lipid differed from that extracted before intracytoplasmic membrane synthesis. Undifferentiated exponential-phase cells were found to contain 30% phosphatidylcholine, 27.1% caridolipin, 25% phosphatidylethanolamine, 12.5% phosphatidylglycerol, 0.4% phosphatidic acid, 0.2% phosphatidylserine, and four additional unidentified lipids totaling less than 5%. The only change detected after formation of intracytoplasmic membranes was a slight decrease in phosphatidylethanolamine and a corresponding increase in phosphatidylcholine. An examination of lipid hydrolysates revealed 11 different fatty acids in the lipids from each cell type. Hexadecanoic acid and monounsaturated octadecenoic accounted for more than 75% of the total fatty acids for both cell types. Proportional changes were noted in all fatty acids except octadecenoate. Anteiso-pentadecanoate comprised less than 1% of the fatty acids from undifferentiated cells but more than 13% of the total fatty acids from cells containing intracytoplasmic membranes. These results suggest that anteiso-pentadecanoate formation closely parallels the formation of intracytoplasmic membranes. Increased concentrations of this fatty acid may contribute to the fluidity necessary for plasma membrane convolution during intracytoplasmic membrane development.
Synthesis and activities of branched-chain aminoacyl-tRNA synthetases in threonine deaminase mutants of Escherichia coli
Authors: Williams A L , Whitfield S M , Williams L S
Published: January 2020

Valyl-, isoleucyl-, and leucyl-tRNA synthetase activities were examined in an Escherichia coli K-12 strain that possessed a deletion of three genes of the ilv gene cluster, ilvD, A, and C, and in a strain with the same deletion that also carried the lambdadilvCB bacteriophage. It was observed that the branched-chain tRNA synthetase activities of both strains were considerably less than those of the normal strain during growth in unrestricted medium. Furthermore, during an isoleucine limitation, there was a further reduction in isoleucyl-tRNA synthetase activity and an absence of the isoleucine-mediated derepression of valyl-tRNA synthetase formation in both of these mutants, as compared with the normal strain. In addition, it was observed that these branched-chain synthetase activities were reduced in steady-state cultures of several ilvA point mutants. However, upon the introduction of the ilv operon to these ilvA mutants by use of lambda bacteriophage, there was a specific increase in the branched-chain synthetase activities to levels comparable to those of the normal strain. These results support our previous findings that the stability and repression control of synthesis of these synthetases require some product(s) missing in the ilvDAC deletion strain and strongly suggest this component is some form of the ilvA gene product, threonine deaminase.
Citrobacter O-antigens: structure of the O-antigenic polysaccharide from Citrobacter sp. 396
Authors: Jann B , Prehm P , Jann K
Published: January 2020

The structure of the O-specific polysaccharide moiety of the lipopolysaccharide from Citrobacter 396 was elucidated by composition, methylation, and periodate oxidation studies. The repeating unit consists of four 2-linked mannoses and one 3-linked N-acetylglucosamine. One of the mannose units is substituted at C3 with alpha-glucose, and one is substituted at C3 with alpha-(2-O-acetyl)-abequose. All the mannosyl linkages appear to have the beta-configuration; the N-acetylglucosaminyl linkage has the alpha-configuration. In bacterial agglutination and passive hemagglutination in some Salmonella antisera, Citrobacter 396 as well as its O-antigenic lipopolysaccharide expressed the serological factors 5 and 6. In corroboration of our structural studies, this showed the presence of alpha-(2-O-acetyl)-abequosyl-1,3-mannose (factor 5) and alpha-glucosyl-1,3-mannose (factor 6).
Purification and properties of the inducible nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase from Chlorella sorokiniana
Authors: Gronostajski R M , Yeung A T , Schmidt R R
Published: January 2020

The nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (NADP-GDH) of Chlorella sorokiniana was purified 260-fold to electrophoretic homogeneity in six steps. Depending on the techniques used, the native enzyme appeared to have a molecular weight of 290,000 or 410,000 and to be composed of five to seven identical subunits with a molecular weight of 58,000. The amino acid composition of this enzyme was shown to differ considerably from that of the NAD-GDH in this organism. The NH2-terminal amino acid was unavailable to dansylation. All six cysteines in the native enzyme were in the free sulfhydryl form. The pH optima for the aminating and deaminating reactions were 7.2 and 9.2, respectively. The Km values for NH4+, alpha-ketoglutarate, NADPH, L-glutamate, and NADP+ were 68, 12, 0.13, and 0.038 mM, respectively. At low substrate concentrations, no cooperativity was seen; however, severe inhibition of enzyme activity was observed at high alpha-ketoglutarate concentrations. Nucleotides did not affect enzyme activity. Antiserum produced in rabbits to the subunits of the enzyme yielded a single precipitin band with the purified enzyme in Ouchterlony double-diffusion analysis. Immunoelectrophoresis was used to confirm the purity of the enzyme and also to quantify the amount of enzyme antigen. These studies indicate that the NADPH-GDH and NAD-GDH isozymes are distinct molecular species in this organism.
Replication of the nonconjugative plasmid RSF1010 in Escherichia coli K-12
Authors: de Graaff J , Crosa J H , Heffron F , Falkow S
Published: January 2020

Replicating DNA molecules of the nonconjugative R plasmid RSF1010 (Smr Sur) were cleaved with the EcoRI restriction endonuclease and examined with the electron microscope. Results of this analysis indicated that replication is initiated from an origin located at about 19% of total genome size from one of the EcoRI ends. Replication proceeded either unidirectionally or bidirectionally with equal frequency. Results of the analysis of replicative intermediates of RSF1010 containing the Apr-transposable sequence (Tn) are also presented.