bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological roles of glutamine synthetases I and II in ammonium assimilation in Rhizobium sp. 32H1
Authors: Ludwig R A
Published: January 2020

The two glutamine synthetases of Rhizobium sp. 32H1 appear to be structurally and functionally distinct. Glutamine synthetase I was reversibly adenylylated, and its synthesis was repressed only twofold by ammonium. When in the unadenylylated configuration, it was the enzyme which allowed the organism to grow, albeit marginally, on ammonium as a nitrogen source. There is no evidence to suggest that the second enzyme, glutamine synthetase II, is regulated by adenylylation. However, this enzyme was repressed at least 50-fold by even low amounts of ammonium. Glutamine synthetase II does not seem to function in ammonium assimilation but rather in purine biosynthesis.
In vivo and in vitro kinetics of nitrogenase
Authors: Davis L C , Wang Y L
Published: January 2020

We measured some of the kinetic parameters of nitrogenase to intact systems of Clostridium pasteurianum and Klebsiella pneumoniae to compare them with the kinetics of the enzyme in vitro. We found that the enzyme showed multiple apparent Km values for acetylene reduction in vivo, as it does in vitro. Carbon monoxide was a noncompetitive inhibitor of acetylene reduction; azide was a noncompetitive inhibitor of acetylene reduction, and nitrogen was a partial inhibitor of acetylene reduction. Cyanide was a noncompetitive inhibitor of acetylene reduction in C. pasteurianum but it was a metabolic poison in K. pneumoniae, in addition to being an inhibitor of nitrogenase. The partial nature of nitrogen inhibition was apparent in assays where both nitrogen and CO were present. Nitrogen did not alter the apparent Ki for CO, nor did the presence of CO enhance the competitive effectiveness of nitrogen. By using recombined nitrogenase fractions, we found that the ability of nitrogen to inhibit hydrogen evolution or acetylene reduction varied with the ratio of protein components. The in vivo inhibition of acetylene reduction by dinitrogen was comparable to that obtained with an excess of the Fe protein in vitro. We conclude that there is an effective excess of the Fe protein available under active growth conditions in vivo.
Structure of the principal carotenoid pigment of Cellulomonas biazotea
Authors: Weeks O B , Montes A R , Andrewes A G
Published: January 2020

The yellow-pigmented Cellulomonas biazotea, ATCC 486, contains a mixture of carotenoids. The principal compound is a decapreno carotenoid (C50H72O2) tentatively characterized as 2,2'-bis(4-hydroxy-3-methyl-2-butenyl)-gamma,gamma-carotene on the basis of electronic absorption, infrared, proton magnetic resonance, and mass spectrometries. The carotenoid is presumed to be identical to sarcinaxanthin from Sarcina lutea pro-synon. Micrococcus luteus and, therefore, is isomeric with decaprenoxanthin from Cellulomonas dehydrogenans.
Isolation and partial characterization of two plasmid deoxyribonucleic acids from endosymbiotic bacteria of Amoeba proteus
Authors: Han J H , Jeon K W
Published: January 2020

Obligatory endosymbiotic bacteria in a strain of Amoeba proteus were found to harbor two distinct species of plasmid, pHJ11 and pHJ12. Their molecular weights were 39 x 10(6) and 14 x 10(6), respectively.
Glutamic acid codon suppressors derived from a unique species of glycine transfer ribonucleic acid
Authors: Murgola E J , Bryant J E
Published: January 2020

In this paper we describe the successful isolation of glyT-derived GAA suppressors. A glyT+ strain containing glyV55, the gene for a GGA/G-reading, methane sulfonate and hydroxylamine. The cells were plated to select for reversal of auxotrophy due to a trpA(GAA211) mutation. With either mutagen, greater than 85% of the prototrophs obtained were due to suppressors of the trpA mutation. Approximately 12% of the ethyl methane sulfonate-induced and 37% of the hydroxylamine-induced suppressors were shown to be about 25% cotranscucible with metB, as is glyT. The transfer ribonucleic acid from four metB-linked suppressor strains (two from each mutagen) was examined by reversed-phase column (RPC-5) chromatography. In all four cases, the glycyl-transfer ribonucleic acid profile displayed an alteration of glyT transfer ribonucleic acid. All four suppressors responded to GAG in addition to GAA but did not suppress the known mutant codons of several other trpA mutants. Other properties are discussed, along with possible reasons for our success in obtaining these suppressors.
Salmonella typhimurium LT2 mutation affecting the deletion of resistance determinants on R plasmids
Authors: Watanabe H , Hashimoto H , Mitsuhashi S
Published: January 2020

Plasmid Rms312, specifying resistance to tetracycline (Tc), chloramphenicol (Cm), streptomycin (Sm), sulfonamide (Su), and mercury chloride (Mer), deletes both Tc and Cm Sm Su Mer determinants at a high frequency in Salmonella typhimurium LT2. S. typhimurium mutants that were stable carriers of Rms312 were isolated by alternate culture of R-bearing cells in a medium containing either tetracycline or chloramphenicol. In one of these mutants the deletion frequency of drug resistance determinants was decreased by about 100-fold not only Rms312, but also in R100, R1, and R6-5. This mutation caused a slight reduction of ultraviolet resistance but did not affect generalized genetic recombination, indicating that the mutation is different from recA. The mutation, designated dor (deletion of r-determinants), was mapped to a position near 57 units in the new linkage map of S. typhimurijm LT2 (K. E. Sanderson and P. E. Hartman, Microbiol. Rev. 42:471-519, 1978). The dor mutation had no effect on IS1-mediated illegitimate deletion, indicating that the dor mutation is different from the del mutation described by Nevers and Saedler (P. Nevers and H. Saedler, Mol. Gen. Genet. 160:209-214, 1978).
Subunit constituent of the porin trimers that form the permeability channels in the outer membrane of Salmonella typhimurium
Authors: Ishii J , Nakae T
Published: January 2020

The polypeptide composition of the functional porin trimers that produced the permeability channels in the outer membrane of Salmonella typhimurium was examined on two-dimensional slab gels. The results suggested that the majority of porin trimers from strains producing mixed species of porin polypeptides consisted of homologous subunit polypeptides. The present results do not exclude the possibility that a small fraction of porin trimer is constructed from heterologous subunit polypeptides.
Outer membrane of Escherichia coli: properties of the F sex factor traT protein which is involved in surface exclusion
Authors: Manning P A , Beutin L , Achtman M
Published: January 2020

The traT protein (TraTp) of the F sex factor is the product of one of the two genes involved in surface exclusion. Several detergents were examined under different conditions in order to determine their ability to solubilize TraTp from membrane vesicles. These experiments showed that TraTp behaved similar to a number of peptidoglycan-associated outer membrane proteins and that it existed in multimeric aggregates within the membrane. However, unlike other major outer membrane proteins, the amount of TraTp incorporated into the membrane was not affected by lipopolysaccharide-deficient mutants, even when mutants totally lacking the neutral sugars in their lipopolysaccharide backbone were used. TraTp wqs also examined by two-dimensional gel electrophoresis, where it ran as a discrete spot with a very basic isoelectric point. By coupling cyanogen bromide-activated dextran onto whole cells and by labeling whole cells with 125I (via lactoperoxidase), it was shown that TraTp was exposed on the cell surface. TraTp in a membrane environment was also insensitive to proteolytic attack by trypsin.
Regulation of membrane phospholipid syntheesis in Escherichia coli during temperature up-shift
Authors: Kainuma-Kuroda R , Goelz S , Cronan J E
Published: January 2020

The synthesis of membrane phospholipids and that of stable ribonucleic acid were inhibited during temperature up-shift of both rel+ and relA strains of Escherichia coli. The kinetics of the inhibition of the synthesis of both molecules were correlated with the kinetics of guanosine 5'-diphosphate-3'-diphosphate synthesis. Metabolic down-shift experiments gave similar results.
Autolysis of Escherichia coli
Authors: Leduc M , van Heijenoort J
Published: January 2020

Autolysis of unwashed exponential-phase Escherichia coli cells was efficiently promoted by first submitting them to a quick downshock with distilled water before an upshock with 0.5 M sodium acetate, pH 6.5. The association of these two osmotic shocks had a remarkable synergistic effect and led to significant decreases in turbidity and viability. Different factors influencing the rate of cell lysis were examined. A close correlation was established between autolysis and the degradation of peptidoglycan. Both phenomena were induced by the same shock treatment, followed similar kinetics, and were efficiently blocked by addition of divalent cations. Cell lysis was also inducible by a shock treatment with 10(-3) M ethylenediaminetetraacetic acid or ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid and blocked by the addition of divalent cations.
Purification and preliminary characterization of Spiroplasma fibrils
Authors: Townsend R , Archer D B , Plaskitt K A
Published: January 2020

Fibrils 3.5 nm in diameter were released from the honeybee spiroplasma (BC3) by treatment with detergents and then purified by isopycnic centrifugation. Purified fibrils were flexuous, of indeterminate length, and had an axial repeat of 8.5 nm. The fibrils were associated in pairs, but in 1 M salt formed aggregates with a marked striated appearance. Pronase completely degraded the fibrils, but trypsin had little effect. The fibrils were composed of a single protein of molecular weight 55,000 which represented about 1% of the total cell protein. A protein of molecular weight 26,000 appeared to be associated with the fibrils. The significance of this in relation to membrane attachment and the possible role of fibrils in maintenance of cell shape and in motility are discussed.
Photocontrol of development by Stigmatella aurantiaca
Authors: White D , Shropshire W , Stephens K
Published: January 2020

Aggregation and fruiting body formation by Stigmatella aurantiaca were stimulated most effectively by low irradiances of blue light between 400 and 500 nm. At higher irradiances, other wavelengths of light, including those in the far-red region of the spectrum, were also effective.
Alcohol-induced changes in the phospholipid molecular species of Escherichia coli
Authors: Berger B , Carty C E , Ingram L O
Published: January 2020

In Escherichia coli, the additon of ethanol resulted in the synthesis of an increased proportion of phospholipids containing two unsaturated fatty acids. The addition of hexanol resulted in the opposite effect, an increase in the proportion of monounsaturated molecular species. The alcohol-induced changes were quantitatively similar to those caused by changing growth temperature. These results suggest that both adaptation to temperature and alcohol-induced changes in lipid composition share some common regulatory features.
Lipids and lipoteichoic acid of autolysis-defective Streptococcus faecium strains
Authors: Shungu D L , Cornett J B , Shockman G D
Published: January 2020

Two of four previously isolated autolysis-defective mutants of Streptococcus faecium (Streptococcus faecalis ATCC 9790) incorporated substantially more [14C]glycerol into lipids and lipoteichoic acid than did the parent strain. Consistent with increased accumulation of lipids and lipoteichoic acid, significantly higher levels of phosphorus were found in the corresponding fractions of the two mutant strains than in the wild type. Although the autolysis-defective mutant strains contained the same assortment of lipids as the wild type, the relative amount of [14C]glycerol incorporated into diphosphatidylglycerol increased, accompanied by a decreased fraction of phosphatidylglycerol. These results suggested that increased cellular content of two types of substances, acylated lipoteichoic acid and lipids (notably diphosphatidylglycerol), which previously had been shown to be potent inhibitors of the N-acetylmuramoylhydrolase of this species, contributed to the autolysis-defective phenotype of these mutants. Consistent with this interpretation are observations that (i) cerulenin inhibition of fatty acid synthesis increased the rates of benzylpenicillin-induced cellular lysis and that (ii) Triton X-100 or Zwittergent 3-14 treatment could reveal the presence of otherwise cryptic but substantial levels of the active form of the autolysin in cells of three of four mutants and of the proteinase-activable latent form in all four mutants.
Involvement of genes uvrD and recB in separate mutagenic deoxyribonucleic acid repair pathways in Escherichia coli K-12 uvrB5 and B/r uvrA155
Authors: Sargentini N J , Smith K C
Published: January 2020

We compared the ultraviolet radiation-induced reversion of nonsense (lacZ53) and missense (leuB19) mutations in uvrB5, uvrB5 uvrD3, uvrB5 recB21, and uvrB5 uvrD3 recB21 strains of Escherichia coli K-12. Nonsense (trpE65) reversion was also compared in similar derivatives of E. coli B/r uvrA155. The uvrD mutation reduced mutagenesis in very case, but had its main effect in cells ultraviolet irradiated with low fluences (< 0.6 J m-2). The effect of the recB mutation varied; it decreased Leu and Trp reversion, but had little effect on Lac reversion. The effect of the uvrD recB combination was a gross reduction in mutagenesis. Only in the case of Lac reversion was appreciable mutagenesis detected (at fluences > 0.3 J m-2). These results indicate that separate uvrD- and recB-controlled pathways exist for ultraviolet radiation mutagenesis.
Lincomycin increases synthetic rate and periplasmic pool size for cholera toxin
Authors: Levner M H , Urbano C , Rubin B A
Published: January 2020

Increased enterotoxigenicity of Vibrio cholerae 569B grown with low concentrations of lincomycin, previously described in terms of increased extracellular biological activity (capillary permeability factor and fluid accumulation in ligated rabbit ileal loops), was further characterized. Polyacrylamide gel electrophoresis and single radial immunodiffusion showed that lincomycin-stimulated cells produced increased molar quantities of cholera toxin (CT) both extra- and intracellularly. The intracellular CT was released in comparable amounts by sonication, deoxycholate extraction, and polymyxin B treatment. Polymyxin B release of CT was nearly complete under conditions wherein only 6% of total cellular beta-galactosidase was released, implying a periplasmic pool of CT in stimulated cells. No intracellular choleragenoid (CT subunit B) was found in stimulated cells by polymyxin B release. No proteolysis of 14C-labeled CT was detected after prolonged incubation with sonicated nonstimulated cultures or sonicated concentrated cells. These data support the conclusion that the stimulatory effect of lincomycin involves an increase in the rate of synthesis of the CT molecule, and argue against alternative models involving inhibition of putative normal degradation of CT, increased release of otherwise cell-bound CT, or activation of inactive, or less active, forms of CT.
Influence of Bacteriophage PBS1 and φW-14 Deoxyribonucleic Acids on Homologous Deoxyribonucleic Acid Uptake and Transformation in Competent
Bacillus subtilis
Authors: López Paloma , Espinosa Manuel , Piechowska Mirosława , Shugar David
Published: January 2020

Both bacteriophage PBS1 deoxyribonucleic acid (DNA) (in which all the thymine residues are replaced by uracil) and phage φW-14 DNA [in which half the thymine residues are replaced by 5-(aminobutylaminomethyl)uracil or 5-putrescinylthymine] exhibit comparable competing abilities for uptake of homologous DNA in a
Bacillus subtilis
competent system. But, whereas PBS1 DNA leads to a decrease in transformation frequencies compatible with its competing ability for DNA uptake, φW-14 DNA decreases transformation frequencies by a factor up to eightfold higher. The effect of φW-14 DNA on transformation frequencies is visible even at a concentration level that does not decrease transforming DNA uptake. No such effect was observed with heterologous DNA containing presumably ionically bound putrescine. Low concentrations of φW-14 DNA decreased the number of double (nonlinked) transformants more than single transformants. The influence on transformation was abolished when φW-14 DNA was added 20 min after addition of transforming DNA, i.e., when the recombination process was terminated. The putrescine-containing DNA also decreased retention of trichloroacetic acid-precipitable radioactivity of homologous DNA taken up. We conclude that φW-14 DNA inhibits some intracellular process(es) at the level of recombination. In addition, there is evidence that φW-14 DNA, but not heterologous DNA with ionically bound putrescine, binds also to site(s) on the cell surface other than receptors for homologous DNA.
Evidence for isofunctional enzymes used in m-cresol and 2,5-xylenol degradation via the gentisate pathway in Pseudomonas alcaligenes
Authors: Poh C L , Bayly R C
Published: January 2020

Study of the reaction sequence by which Pseudomonas alcaligenes (P25X1) and derived mutants degrade m-cresol, 2,5-xylenol, and their catabolites has provided indirect evidence for the existence of two or more isofunctional enzymes at three different steps. Maleylpyruvate hydrolase activity appears to reside in two different proteins with different specificity ranges, one of which (MPH1) is expressed constitutively; the other (MPH11) is strictly inducible. Two gentisate 1,2-dioxygenase activities were found, one of which is constitutively expressed and possesses a broader specificity range than the other, which is inducible. From oxidation studies with intact cells, there appear to be two activities responsible for the 6-hydroxylation of 3-hydroxybenzoate, and again a broadly specific activity is present regardless of growth conditions; the other is inducible by 3-hydroxybenzoate. Three other enzyme activities are also detected in uninduced cells, viz., xylenol methylhydroxylase, benzylalcohol dehydrogenase, and benzaldehyde dehydrogenase. All apparently possess broad specificity. Fumarylpyruvate hydrolase was also detected but only in cells grown with m-cresol, 3-hydroxybenzoate, or gentisate. Mutants, derived either spontaneously or after treatment with mitomycin C, are described, certain of which have lost the ability to grow with m-cresol and 2,5-xylenol and some of which have also lost the ability to form the constitutive xylenol methylhydroxylase, benzylalcohol dehydrogenase, benzaldehyde dehydrogenase, 3-hydroxybenzoate 6-hydroxylase, and gentisate 1,2-dioxygenase. Such mutants, however, retain ability to synthesize inducibly a second 3-hydroxybenzoate 6-hydroxylase and gentisate 1,2-dioxygenase, as well as maleylpyruvate hydrolase (MPH11) and fumarylpyruvate hydrolase; MPH1 was still synthesized. These findings suggest the presence of a plasmid for 2,5-xylenol degradation which codes for synthesis of early degradative enzymes. Other enzymes, such as the second 3-hydroxybenzoate 6-hydroxylase, gentisate 1,2-dioxygenase, maleylpyruvate hydrolase (MPH1 and MPH11), and fumarylpyruvate hydrolase, appear to be chromosomally encoded and, with the exception of MPH1, strictly inducible.
Isolation of two protein-free and chemically different lipopolysaccharides from Bordetella pertussis phenol-extracted endotoxin
Authors: Le Dur A , Chaby R , Szabó L
Published: January 2020

Endotoxin prepared from several Bordetella pertussis strains in both immunological phases I and IV gave two lipopolysaccharide peaks (LPS-I and LPS-II) when analyzed on hydroxylapatite columns in a phosphate buffer containing 0.1% sodium dodecyl sulfate; these lipopolysaccharides, present in the ratio of 2:3, are true endotoxins by both chemical and biological criteria. Endotoxins isolated from Escherichia coli, Salmonella typhimurium, and Shigella flexneri gave single lipopolysaccharide peaks when analyzed by the same procedure. Upon hydrolysis with acetic acid (pH 3.4) at 100 degrees C for 1 h, LPS-I released a polysaccharide (PS-I); the linkage broken was that of the glycosidic bond of a non-phosphorylated 3-deoxy-oct-2-ulosonic acid. Treatment with 0.25 M mineral acid at 100 degrees C for 30 min was required to free the polysaccharide moiety (PS-II) of LPS-II, the linkage broken being the glycosidic bond of a phosphorylated 3-deoxy-oct-2-ulosonic acid. Chemical and physical differences of the polysaccharide moieties PS-I and PS-II present in LPS-I and LPS-II have been described previously (25). By using the technique of 125I labeling, it was shown that the totality of labeled proteins present in the endotoxin extracted from Bordetella pertussis by the phenol-water procedure could be separated from the lipopolysaccharide by column chromatography on hydroxylapatite; it follows that these proteins are not linked by covalent bonds to the lipopolysaccharide.
Role of nucleases in the isolation of plasmid deoxyribonucleic acid from Pseudomonas cepacia 4G9
Authors: Williams J A , Yeggy J P , Markovetz A J
Published: January 2020

Brij 58-cleared lysates of Pseudomonas cepacia 4G9 contain both exonucleolytic and endonucleolytic activities. Endonuclease activity was unaffected by 125 mM ethylenediaminetetraacetic acid, whereas the exonuclease activity was inhibited. In contrast, Sarkosyl NL97 inhibited only the endonuclease. Sodium dodecyl sulfate inhibited all nuclease activity in in vitro assays, but plasmid deoxyribonucleic acid added to P. cepacia 4G9 spheroplasts during sodium dodecyl sulfate lysis was degraded. Irreproducible plasmid isolation from P. cepacia 4G9 may be due to this nucleolytic activity.
Protein synthesis results in guanosine-5'-diphosphate-3'-diphosphate synthesis in Escherichia coli minicells
Authors: Nöthling R , Reeve J N
Published: January 2020

Minicells of Escherichia coli DS410 synthesized guanosine-5'-diphosphate-3'-diphosphate and guanosine-5'-triphosphate-3'-diphosphate when synthesizing proteins in response to phage T7 infection. The guanosine-5'-diphosphate-3'-diphosphate synthesis was found to be relA+ dependent and inhibited by chloramphenicol.
Functional relationship between parts of the replication region of plasmid ColE1
Authors: Inselburg J
Published: January 2020

The inhibition of plasmid ColE1 replication caused by a deletion of the ColE1 plasmid replication origin has been previously reported (T. Hashimoto-Gotoh and J. Inselburg, J. Bacteriol. 139:597-619). Evidence is presented showing that restoration of the deleted nucleotide sequence in the precise relationship it normally has to the rest of the replication region is essential for restoration of ColE1 replication capability to the deletion mutant.
Ubiquinone synthetic pathway in flagellation of Salmonella typhimurium
Authors: Bar-Tana J , Howlett B J , Hertz R
Published: January 2020

Flagellation of Salmonella typhimurium was found to require a functional pathway for ubiquinone synthesis as well as growth in the presence of aliphatic or aromatic carboxylic acids. Selection for constitutive flagellation eliminated the requirement for growth in the presence of added carboxylic acids.
Specificity in the formation of delta tra F-prime plasmids
Authors: Hadley R G , Deonier R C
Published: January 2020

Twenty-three independent delta tra F-prime plasmids from three different Escherichia coli K-12 sublines were isolated from Hfr strains whose points of origin coincided with the IS3 element alpha 3 beta 3 or alpha 4 beta 4 in the lac-purE region of the E. coli chromosome. Electrophoretic analysis of plasmid deoxyribonucleic acid digested with EcoRI and hybridization analysis of plasmid deoxyribonucleic acid digested with BglII revealed that at least 14 of these plasmids were formed by processes involving specific bacterial and F loci. Two of the specific bacterial loci involved in delta tra F-prime formation were located at approximately 3.3 and 11.7 min on the E. coli chromosomal map. Two of the delta tra F-prime plasmids contained bacterial deoxyribonucleic acid with circularization endpoints that mapped very near the termini of the IS2 element that is normally located between lac and proC.
Multiple electrophoretic forms of methyl-accepting chemotaxis proteins generated by stimulus-elicited methylation in Escherichia coli
Authors: Boyd A , Simon M I
Published: January 2020

The tsr and tar genetic loci of Escherichia coli determine the presence in sodium dodecyl sulfate-polyacrylamide gel electrophoresis of methyl-accepting chemotaxis proteins (MCPs) I and II, respectively, each of which consists of a distinct group of multiple bands. Synthesis of the tsr and tar products was directed in ultraviolet-irradiated bacteria by lambda transducing phages. The addition of appropriate chemotactic stimuli to these cells resulted in the appearance of additional, faster migrating electrophoretic forms of the Tsr and Tar polypeptides which disappeared upon removal of the stimulus. The stimulus-elicited forms comigrated with component bands of the corresponding MCPs. These results indicate that methylation itself caused shifts in electrophoretic mobility and hence led to the observed MCP band patterns. The number of Tsr species suggested that there were at least three methylated sites on the Tsr polypeptide. The conclusion that methylation generates multiplicity was supported by the results of experiments in which the tsr product was synthesized in mutant bacteria defective in specific chemotaxis functions concerned with methylation or demethylation of MCPs. Thus, the presence of a cheX defect blocked the stimulus-elicited appearance of faster migrating forms of the tsr product; conversely, the presence of a cheB defect resulted in a pronounced shift toward these forms in the absence of a chemotactic stimulus.
Transductional selection of cloned bacteriophage phi 105 and SP02 deoxyribonucleic acids in Bacillus subtilis
Authors: Marrero R , Lovett P S
Published: January 2020

The Bacillus subtilis temperate bacteriophages phi 105 and SP02 are incapable of transduction of the small, multicopy drug resistance plasmids pUB110 and pCM194. Cloning endonuclease-generated fragments of phi 105 or SP02 DNA into each of the plasmids renders the chimeric derivatives susceptible to transduction specifically by the phage whose deoxyribonucleic acid is present in the chimera. The majority of phage deoxyribonucleic acid fragments identified that render plasmids transducible by phi 105 or SP02 appear to be internal fragments, not fragments containing the cohesive ends. However, the highest overall transduction frequency was observed in SP02-mediated transduction of a derivative of pUB110 containing a 1.6-megadalton EcoRI fragment that likely contains the SP02 cohesive ends (plasmid pPL1010). The transducing activity present in a phi 105 transducing lysate had a buoyant density slightly greater than infectious particles, whereas the majority of transducing particles in an SP02(pPL1010) transducing lysate had a buoyant density slightly less than infectious particles. Although no detectable change in plasmid structure resulted from transduction by phi 105 or SP02, deoxyribonucleic acid isolated from a purified SP02(pPL1010) transducing lysate contained no detectable monomeric pPL1010, but did contain a form of pPL1010 of higher molecular weight than the monomer.
Properties of polyadenylate-associated ribonucleic acid from Saccharomyces cerevisiae ascospores
Authors: Harper J F , Clancy M J , Magee P T
Published: January 2020

Bulk ribonucleic acid (RNA) was isolated from mechanically disrupted ascospores of Saccharomyces cerevisiae. After two passes over an oligo (dT10) cellulose column, the portion which bound, called poly(A)(+), was characterized. It is heterodisperse in size with a mean molecular weight of approximately 4 X 10(5), but contains some species as large as 7 X 10(5). The base composition is similar to vegetative poly(A)(+) RNA. The polyadenylate segment is also heterogenous in size, ranging from 90 to 20 bases in length, with a peak at approximately 60 nucleotides in length. Pulse-labeling of asci with [3H-methyl]methionine yields two "caps," 7-methyl guanosine-5'-triphosphoryl-5'-adenosine (or guanosine) identical to that found in vegetative poly(A)(+) RNA. The poly(A)(+) RNA in spores is found in polyribosomes which are, on the average, smaller than vegetative ones. Long-term labeling studies indicate that the fraction of poly(A)(+) RNA in spores is similar to that in vegetative cells.
Active transport and accumulation of bicarbonate by a unicellular cyanobacterium
Authors: Miller A G , Colman B
Published: January 2020

The rates of inorganic carbon accumulation and carbon fixation in light by the unicellular cyanobacterim Coccohloris peniocystis have been determined. Cells incubated in the light in medium containing H14CO3- were rapidly separated from the medium by centrifugation through silicone oil into a strongly basic terminating solution. Samples of these inactivated cells were assayed to determine total 14C accumulation, and acid-treated samples were assayed to determine 14C fixation. The rate of transport of inorganic into illuminated cells was faster than the rate of CO2 production in the medium from HCO3- dehydration. This evidence for HCO3- transport in these cells is in agreement with our previous results based upon measurements of photosynthetic O2 evolution. A substantial pool of inorganic carbon was bulit up within the cells presumably as HCO3- before the onset of the maximum rate of photosynthesis. Large accumulation ratios were observed, greater than 1,000 times the external HCO3- concentration. Accumulation did not occur in the dark and was greatly suppressed by the photosynthesis inhibitors 3-(3,4-dichlorophenyl)-1,1-dimethyl urea and 3-chloro-carbonylcyanide phenylhydrazone. These results indicate that the accumulation of inorganic carbon in these cells involves a light-dependent active transport process.
Synthesis and utilization of siderophores by Shigella flexneri
Authors: Payne S M
Published: January 2020

Strains of Shigella flexneri secrete a hydroxamate-type siderophore when grown in low-iron media. This hydroxamate appears to be identical with aerobactin, a siderophore synthesized by Aerobacter aerogenes. In contrast to other enteric bacteria, S. flexneri did not produce detectable phenolate siderophores, although it could utilize an exogenously supplied phenolate.
Relationship between proton motive force and motility in Spirochaeta aurantia
Authors: Goulbourne E A , Greenberg E P
Published: January 2020

The effects of various metabolic inhibitors on the motility of Spirochaeta aurantia were investigated. After 15 min in sodium arsenate buffer, 90% of cells remained motile even though adenosine triphosphate levels dropped from 5.6 to 0.1 nmol/mg (dry weight) of cells. After 70 min in sodium arsenate, 5% of cells were motile. Addition of phenazine methosulfate plus ascorbate at this time resulted in motility of 95% of cells, but adenosine triphosphate levels remained at 0.1 nmol/mg of cell dry weight. Carbonyl cyanide-m-chlorophenyl hydrazone rapidly (within 1 min) and completely inhibited motility of metabolizing cells in potassium phosphate buffer. However, after 15 min in the presence of carbonyl cyanide m-chlorophenyl hydrazone the cellular adenosine triphosphate level was 3.4 nmol/mg (dry weight) of cells, and the rate of oxygen uptake was 44% of the rate measured in the absence of carbonyl cyanide m-chlorophenyl hydrazone. Cells remained motile under conditions where either the electrical potential or the pH gradient across the membrane of S. aurantia was dissipated. However, if both gradients were simultaneously dissipated, motility was rapidly inhibited. This study indicates that a proton motive force, in the form of either a transmembrane electrical potential or a transmembrane pH gradient, is required for motility in S. aurantia. Adenosine triphosphate does not appear to directly activate the motility system in this spirochete.
Isolation and characterization of multiflagellate mutants of Pseudomonas aeruginosa
Authors: Suzuki T , Iino T
Published: January 2020

Multitrichously polar flagellated mutants were isolated from a monotrichously flagellated strain of Pseudomonas aeruginosa. The ability of the mutant cells to swarm in semisolid media at given gel strengths was increased by the multiflagellation. Observations of the mutant cells by electron microscopy revealed that the number of flagella produced per cell cycle was increased. F116 phage-mediated transduction showed that the multiflagellation occurred by a single mutation and that the mutation sites were linked to a fla cluster of this organism.
Genetic mapping of the Salmonella typhimurium pepB locus
Authors: Green L , Miller C G
Published: January 2020

Transposon technology has been used to map the pepB locus of Salmonella typhimurium. This locus is cotransducible by phage P22 with glyA and strB at min 56 on the Salmonella genetic map. The gene order is strB pepB glyA.
Lactose operon transcription from wild-type and L8-UV5 lac promoters in Escherichia coli treated with chloramphenicol
Authors: Hirschel B J , Shen V , Schlessinger D
Published: January 2020

In cells treated with chloramphenicol and the inducer isopropyl-beta-D-thiogalacto-pyranoside, messenger ribonucleic acid transcription from the wild-type lac promoter was not detected. Transcription occurred from the mutant UV5-L8 promoter. The transcripts were of variable length; some included the whole Z gene. No major site of transcription arrest within the Z gene was apparent.
Suppression of defects in cyclic adenosine 3',5'-monophosphate metabolism in Escherichia coli
Authors: Alexander J K
Published: January 2020

Strain MM6-13 (ptsI suc lacI sup) of Escherichia coli contains a suppressor of the succinate-negative phenotype. In MM6-13, sup caused enhanced growth in glycerol, maltose, melibiose, and succinate media and increased activity of beta-galactosidase and tryptophanase relative to an isogenic strain without sup. In strain A61 (cya sup), sup partially suppressed cya. Cyclic guanosine monophosphate increased beta-galactosidase activity sevenfold in A61 and enabled this strain to grow on maltose, galactose, succinate, and arabinose. Strain A61 responded to much lower concentrations of cyclic adenosine monophosphate than cyclic guanosine monophosphate. It appears that sup is located in the crp locus. These results suggest that sup mutants have an altered cyclic adenosine monophosphate receptor protein which is activated by cyclic guanosine monophosphate and has an increased affinity for cyclic adenosine monophosphate.
Effects of carbon source and growth rate on cell wall composition of Bacillus subtilis subsp. niger
Authors: Kruyssen F J , de Boer W R , Wouters J T
Published: January 2020

A study was made to determine whether factors other than the availability of phosphorus were involved in the regulation of synthesis of teichoic and teichuronic acids in Bacillus subtilis subsp. niger WM. First, the nature of the carbon source was varied while the dilution rate was maintained at about 0.3 h-1. Irrespective of whether the carbon source was glucose, glycerol, galactose, or malate, teichoic acid was the main anionic wall polymer whenever phosphorus was present in excess of the growth requirement, and teichuronic acid predominated in the walls of phosphate-limited cells. The effect of growth rate was studied by varying the dilution rate. However, only under phosphate limitation did the wall composition change with the growth rate: walls prepared from cells grown at dilution rates above 0.5 h-1 contained teichoic as well as teichuronic acid, despite the culture still being phosphate limited. The wall content of the cells did not vary with the nature of the growth limitation, but a correlation was observed between the growth rate and wall content. No indications were obtained that the composition of the peptidoglycan of B. subtilis subsp. niger WM was phenotypically variable.
Immunochemical studies of the mannans of Saccharomyces cerevisiae X2180-1A-5 and Saccharomyces cerevisiae 4484-24D-1 mutant strains, with special reference to their phosphate content
Authors: Okubo Y , Shibata N , Matsumoto T , Suzuki M , Schuerch C , Suzuki S
Published: January 2020

The mannans from Saccharomyces cerevisiae mutant strains X2180-1A-5 and 4484-24D-1, both of which were shown to contain small amounts of phosphate (less than 0.2%), were fractionated on a column of diethylaminoethyl-Sephadex into five subfractions designated as fractions I to V. These subfractions contain different amounts of phosphate, ranging from 0.03 to 0.09 (strain X2180-1A-5) and from 0.01 to 0.17% (strain 4484-24D-1). Fractions I to IV from strain X2180-1A-5 showed nearly identical precipitin activities against the homologous anti-whole cell serum, whereas fraction V, containing the largest amount of phosphate and protein among this mannan subfraction series, showed unexpectedly weaker precipitin activity than those of the other fractions. A synthetic mannan consisting or consecutive alpha-1 leads to 6-linked D-mannopyranosyl residues was found to be cross-reactive with all the mannan subfractions of strain X2180-1A-5 against anti-X2180-1A-5 serum. On the other hand, antibody-precipitating activities of the mannan subfractions of the latter strain were proportional to their phosphate content, although the increments of precipitated antibody nitrogen among the subfractions were quite small. However, fraction V of this mannan subfraction series, containing the largest amounts of phosphate and protein, showed lower precipitin activity than did the other four fractions. These findings indicate that mannans containing no phosphate or relatively small amounts of phosphate, such as those investigated in the present study, are less heterogeneous in the densities of the branching moieties than are highly phosphorylated mannans. These findings suggest that the transfer step of mannosyl-1-phosphate into the precursor(s) of the wild-type strain mannans during the biosynthetic process corresponds to the key reaction responsible for the anionic heterogeneity due to the density heterogeneity of the antigenic determinants.
Synthesis of recA protein and induction of bacteriophage lambda in single-strand deoxyribonucleic acid-binding protein mutants of Escherichia coli
Authors: Baluch J , Chase J W , Sussman R
Published: January 2020

We investigated the capacity of Escherichia coli mutants defective in the single-strand deoxyribonucleic acid (DNA)-binding protein to amplify the synthesis of the recA protein, induce prophage lambda, and degrade their DNA after treatment with ultraviolet radiation, mitomycin C, or bleomycin. The thermosensitive ssbA1 strain induced recA protein and lambda phage normally at 30 degrees C, but no induction was observed at 42 degrees C when ultraviolet radiation or mitomycin C was used. The lexC113 mutant did not amplify recA protein synthesis or induce phage lambda at either 30 or 42 degrees C with those agents. Bleomycin was able to elicit induction of recA and phage lambda in both mutants at any temperature. After induction with ultraviolet radiation at the elevated temperature, no DNA degradation was observed for 40 min, but at later times there was increased degradation in the lexC113 strain, compared with the wild type, and even greater degradation in the ssbA1 mutant. We discuss the role of single-strand DNA-binding protein in induction and the possibility that the lexC product may exert its influence on recA and lambda induction at the level of the single-strand DNA gap.
Escherichia coli K317, formerly used to define colicin group E2, produces colicin E7, is immune to colicin E2, and carries a bacteriophage-restricting conjugative plasmid
Authors: Males B M , Stocker B A
Published: January 2020

Escherichia coli strain CL137, a K-12 derivative made E colicinogenic by contact with Fredericq's strain K317, was unaffected by colicin E2-P9, but K-12 carrying ColE2-P9 was sensitive to the E colicin made by strains CL137 and K317. This colicin we named E7-K317 because by the test of colicinogenic immunity it differed from colicins E1-K30, E2-P9, and E3-CA38 and from recently recognized colicins termed E4Horak, E5, and E6. Strain K317 as conjugational donor transmitted E7 colicinogeny; about half the E7-colicinogenic transconjugants were immune to colicin E2-P9. A spontaneous variant of CL137 retained E7 colicinogeny but was sensitive to E2 colicins. We attribute the E2 immunity of strain CL137 and some E7-coliconogeic transconjugants to a "colicin-immunity plasmid," ColE2imm-K317, from strain K317. Tra+ E7-colicinogenic transconjugants restricted phage BF23 in the same way as strains carrying ColIb-P9. We attribute Tra+ and restricting ability to a plasmid, pRES-K317, acquired from strain K317, and related to the ColI plasmids.
Ethanol Production by Thermophilic Bacteria: Relationship Between Fermentation Product Yields of and Catabolic Enzyme Activities in
Clostridium thermocellum
and
Thermoanaerobium brockii
Authors: Lamed R. , Zeikus J. G.
Published: January 2020

Significant quantitative differences in end-product yields by two strains of
Clostridium thermocellum
and one strain of
Thermoanaerobium brockii
were observed during cellobiose fermentation. Most notably, the ethanol/H
2
and lactate/acetate ratios were drastically higher for
T. brockii
as compared with
C. thermocellum
strains LQRI and AS39. Exogenous H
2
addition (0.4 to 1.0 atm) during culture growth increased the ethanol/acetate ratio of both
T. brockii
and AS39 but had no effect on LQRI. All strains had an operative Embden-Meyerhof glycolytic pathway and displayed catabolic activities of fructose-1,6-diphosphate–activated lactate dehydrogenase, coenzyme A acetylating pyruvate and acetaldehyde dehydrogenase, hydrogenase, ethanol dehydrogenase, and acetate kinase. Enzyme kinetic properties (apparent

K
m

,
V
max
, and Q
10
values) and the specificity of electron donors/acceptors for different oxidoreductases involved in pyruvate conversion to fermentation products were compared in the three strains. Both species contained ferredoxin-linked pyruvate dehydrogenase and pyridine nucleotide oxidoreductases. Ferredoxin-nicotinamide adenine dinucleotide (NAD) reductase activity was significantly higher in
T. brockii
than in AS39 and was not detectable in LQRI. H
2
production and hydrogenase activity were inversely related to ferredoxin-NAD reductase activity in the three strains. Ferredoxin-NAD phosphate reductase activity was present in cell extracts of both species. Alcohol dehydrogenase activity in
C. thermocellum
was NAD dependent, unidirectional, and inhibited by low concentrations of NAD and ethanol. Ethanol dehydrogenase activity of
T. brockii
was both NAD and NADP linked, reversible, and not inhibited by low levels of reaction products. The high lactate yield of
T. brockii
correlated with increased fructose-1,6-diphosphate. The relation of catabolic enzyme activity and quantitative differences in intracellular electron flow and fermentation product yields of these thermophilic bacteria is discussed.
Tight linkage of genes that encode the two glutamate synthase subunits of Escherichia coli K-12
Authors: Lozoya E , Sanchez-Pescador R , Covarrubias A , Vichido I , Bolivar F
Published: January 2020

A hybrid deoxyribonucleic acid molecule, plasmid pRSP20, which was isolated from the Clarke and Carbon Escherichia coli gene bank, was shown to complement the gltB31 mutation, which affects the synthesis of glutamate synthase in E. coli strain PA340. We present evidence which demonstrates that plasmid pRSP20 carries an 8-megadalton E. coli chromosomal fragment, including the genes encoding the two unequal glutamate synthase subunits. Polypeptides with molecular weights of about 135,000 and 53,000, which comigrated with purified E. coli glutamate synthase subunit polypeptides and immunoprecipitated with antibodies to E. coli glutamate synthase, were synthesized by minicells carrying the pRSP20 plasmid.
Bacteriophage P1 as a vehicle for Mu mutagenesis of Salmonella typhimurium
Authors: Rosenfeld S A , Brenchley J E
Published: January 2020

We developed a procedure using bacteriophage P1 as a vector for transferring Mu phage deoxyribonucleic acid into Salmonella typhimurium. Mu phage transferred in this manner yielded lysogenic auxotrophs, and we demonstrated that specific deletions and lac gene fusions can be selected.
Enzymological Basis for Growth Inhibition by
l
-Phenylalanine in the Cyanobacterium
Synechocystis
sp. 29108
Authors: Hall Geraldine C. , Jensen Roy A.
Published: January 2020

The pattern of allosteric control in the biosynthetic pathway for aromatic amino acids provides a basis to explain vulnerability to growth inhibition by
l
-phenylalanine (0.2 mM or greater) in the unicellular cyanobacterium
Synechocystis
sp. 29108. We attribute growth inhibition to the hypersensitivity of 3-deoxy-
d
-arabinoheptulosonate 7-phosphate synthase to feedback inhibition by
l
-phenylalanine. Hyperregulation of this initial enzyme of aromatic biosynthesis depletes the supply of precursors needed for biosynthesis of
l
-tyrosine and
l
-tryptophan. Consistent with this mechanism is the total reversal of phenylalanine inhibition by a combination of tyrosine and tryptophan. Inhibited cultures also contained decreased levels of phycocyanin pigments, a characteristic previously correlated with amino acid starvation in cyanobacteria.
l
-Phenylalanine is a potent noncompetitive inhibitor (with both substrates) of 3-deoxy-
d
-arabinoheptulosonate 7-phosphate synthase, whereas
l
-tyrosine is a very weak inhibitor. Prephenate dehydratase also displays allosteric sensitivity to phenylalanine (inhibition) and to tyrosine (activation). Both 2-fluoro and 4-fluoro derivatives of phenylalanine were potent analog antimetabolites, and these were used in addition to
l
-phenylalanine as selective agents for resistant mutants. Mutants were isolated which excreted both phenylalanine and tyrosine, the consequence of an altered 3-deoxy-
d
-arabinoheptulosonate 7-phosphate synthase no longer sensitive to feedback inhibition. Simultaneous insensitivity to
l
-tyrosine suggests that
l
-tyrosine acts as a weak analog mimic of
l
-phenylalanine at a common binding site. Prephenate dehydratase in the regulatory mutants was unaltered. Surprisingly, in view of the lack of regulation in the tyrosine branchlet of the pathway, such mutants excrete more phenylalanine than tyrosine, indicating that
l
-tyrosine activation dominates
l
-phenylalanine inhibition of prephenate dehydratase in vivo. In mutant Phe r19 the loss in allosteric sensitivity of 3-deoxy-
d
-arabinoheptulosonate 7-phosphate synthase was accompanied by a threefold increase in specific activity. This could suggest that existence of a modest degree of repression control (autogenous) over 3-deoxy-
d
-arabinoheptulosonate synthase, although other explanations are possible. Specific activities of chorismate mutase, prephenate dehydratase, shikimate/nicotinamide adenine dinucleotide phosphate dehydrogenase, and arogenate/nicotinamide adenine dinucleotide phosphate dehydrogenase in mutant Phe r19 were identical with those of the wild type.
Prophage induction in a permeabilized cell system: induction by deoxyribonucleases and the role of recBC-deoxyribonuclease
Authors: Irbe R M , Oishi M
Published: January 2020

Permeabilized cells able to induce prophage were obtained by plasmolysis and preincubation of the cells in a reaction mixture which allows protein synthesis. These cells became permeable to low-molecular-weight proteins and oligonucleotides. We found that deoxyribonucleases (pancreatic deoxyribonuclease and micrococcal nuclease) triggered prophage (phi 80) induction. This deoxyribonuclease-triggered induction was completely dependent upon the presence of functional recBC genes in the lysogen, regardless of the recombination proficiency determined by recBC and sbcB genes. The possible role of recBC-deoxyribonuclease in prophage induction and recombination is discussed.