bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of murein biosynthesis and septum formation in filamentous cells of Escherichia coli PAT 84
Authors: Mirelman D , Yashouv-Gan Y , Schwarz U
Published: January 2020

Both the beta-lactam antibiotic, cephalexin, and the deoxyribonucleic acid synthesis inhibitor, nalidixic acid, are known to inhibit cell division in Escherichia coli and induce the formation of filaments. The biosynthesis of murein was investigated in these filaments and compared with the murein synthesized by the normally dividing rods of E. coli PAT 84. Differences were found in the extent of peptide side-chain cross-linkage. Filamentous cells had higher extents of cross-linkages in their newly synthesized murein. Quantitative analyses of the D-alanine carboxypeptidase and transpeptidase reactions in the different cells revealed that the carboxypeptidase activity of the filamentous cells was partially inhibited. These results were similar to those previously found with filaments that were obtained after growth of the thermosensitive division mutant at its restrictive temperature. We conclude that the formation of new cell ends (septa) depends on the proper balance between the activities of the D-alanine carboxypeptidase that regulates the availability of precursor doners and the transpeptidase, which catalyzes cross-linking and attachment of newly synthesized murein.
Medium-dependent variation of deoxyribonucleic acid segregation in Escherichia coli
Authors: Cooper S , Weinberger M
Published: January 2020

The degree to which deoxyribonucleic acid segregates nonrandomly has been investigated for Escherichia coli B/r growing in different media. The degree of nonrandom segregation observed is dependent on the medium, with segregation becoming less random as the growth rate decreases. This indicates that there must be some varying probabilistic component to the segregation process. A probabilistic modification of the Pierucci-Zuchowski model is proposed as well as a probabilistic model, in which it is proposed that deoxyribonucleic acid strands segregate, with a probability greater than 0.5, in the same direction (toward the same pole) as at the previous cell division.
Genetic and physiological relationships between L-asparaginase I and asparaginase II in Saccharomyces cerevisiae
Authors: Jones G E
Published: January 2020

The cistron that codes for L-asparaginase I in Saccharomyces cerevisiae (aspl) is not genetically linked to either of the cistrons coding for expression of asparaginase II (asp2 and asp3). Cells containing different combinations of theses enzymes grow at different rates in media in which L-asparagine or D-asparagine is the only source of nitrogen for cell replication. Cells lacking L-asparaginase I but possessing asparaginase II grow more rapidly in medium containing D-asparagine as a nitrogen source than cells containing both enzymes, even though D-asparagine is not a substrate of L-asparaginase I. These results indicate that L-asparaginase I and asparaginase II interact in some way to regulate the utilization of asparagine as a nitrogen source for cell growth.
Role of the 30S ribosomal subunit, initiation factors, and specific ion concentration in barotolerant protein synthesis in Pseudomonas bathycetes
Authors: Landau J V , Smith W P , Pope D H
Published: January 2020

Washed (1 M NH4Cl) ribosomes from Pseudomonas bathycetes, Pseudomonas fluorescens, and Escherichia coli were tested for their ability to synthesize protein or polypeptide at high pressure when used as such, when recombined with homologous initiation factors, and when recombined with heterologous initiation factors. The responses of natural messenger ribonucleic acid (MS-2)-directed systems to pressure were independent of the source of initiation factors and paralleled those of the washed ribosomes in polyuridylate-directed systems. In all cases, the responses to pressure were parallel to those obtained when unwashed ribosomes were utilized; therefore, we concluded that the initiation factors were interchangeable among these organisms, and that these factors did not play a critical role in determining the pressure responses of the protein-synthesizing systems. P. bathycetes ribosomal subunits were isolated under a variety of ionic conditions. These were tested for their ability to synthesize protein and polyphenylalanine at a variety of pressures when used in reconstituted P. bathycetes homologous systems and in hybrid systems with ribosomal subunits from E. coli and P. fluorescens. O. bathycetes 30S subunits, isolated in a buffer solution containing 0 mM NaCl and O mM KC] were functional at any pressure; those isolated in the presence of 150 mM NaCl and 0 mM KCl were functional at 1 atmosphere but barosensitive, and those isolated in the presence of O mM NaCl and 150 mM KCl retained the ion-mediated barotolerance characteristic of crude P. bathycetes ribosome preparations. The 50S subunit remained functional regardless of the method of isolation, and it had no effect on pressure sensitivity.
Inorganic salts resistance associated with a lactose-fermenting plasmid in Streptococcus lactis
Authors: Efstathiou J D , McKay L L
Published: January 2020

Present evidence indicates that lactose metabolism in group N streptococci is linked to plasmid deoxyribonucleic acid. Lactose-positive (Lac+) Streptococcus lactis and lactose-negative (Lac-) derivatives were examined for their resistance to various inorganic ions. Lac+ S. lactis strains ML3, M18, and C2 were found more resistant to arsenate (7.5- to 60.2-fold), arsenite (2.25- to 3.0-fold), and chromate (6.6- to 9.4-fold), but more sensitive to copper (10.0- to 13.3-fold) than their Lac- derivatives. These results suggested that genetic information for resistance and/or sensitivity to these ions resides on the "lactose plasmid." Kinetics of ultraviolet irradiation inactivation of transducing ability for lactose metabolism and arsenate resistance confirmed the plasmid location of the two markers. Lac+ transductants from S. lactis C2 received genetic determinants for resistance to arsenate, arsenite, and chromate but not for copper sensitivity. In this case, resistance markers were lost when the transductants became Lac- but the derivatives remained copper resistant. The resistant markers for arsenate and arsenite could not be identified as separate genetic loci, but chromate resistance and copper sensitivity markers were found to be independent genetic loci. The "lactose plasmid" from S. lactis C10 possessed the genetic loci for arsenate and arsenite resistance but not for chromate resistance or copper sensitivity.
Suppression of the DnaA phenotype by mutations in the rpoB cistron of ribonucleic acid polymerase in Salmonella typhimurium and Escherichia coli
Authors: Bagdasarian M M , Izakowska M , Bagdasarian M
Published: January 2020

A class of mutations that confer resistance to rifampin in Salmonella typhimurium and Escherichia coli also suppresses the thermosensitivity of chromosome initiation in dnaA mutants. Ribonucleic acid polymerase is resistant to rifampin in vitro in these suppressive mutants, and the suppressors of dnaA cannot be separated from the rpoB mutations by transduction. It is concluded, therefore, that certain rpoB mutations may suppress the DnaA phenotype.
Influence on motility of Escherichia coli and Salmonella typhimurium by a naturally occurring conjugative plasmid
Authors: Bohlin T , Burman L G
Published: January 2020

In a collection of 45 R-plasmids, one was found to be associated with loss of motility of its Escherichia coli K-12 and Salmonella typhimurium host bacteria when tested in conventional motility agar. Genetic experiments, as well as analyses of deoxyribonucleic acid, showed that inhibition of motility was caused by a conjugative plasmid that was separate from the R-plasmid. This second plasmid, named pUM5, was fi- and mediated the same type of sex pilus (F-like) as the accompanying R-plasmid but lacked resistance determinants. Preliminary studies indicated that bacterial cells carrying the motility inhibition plasmid pUM5 were still equipped with flagella. The mechanism by which flagellar action is disturbed by the plasmid is presently not known.
In vitro transcription of the Escherichia coli K-12 argA, argE, and argCBH operons
Authors: Sens D , Natter W , James E
Published: January 2020

Deoxyribonucleic acid isolated from argA and argECBH transducing phages was utilized to study the in vitro synthesis of argA, argE, and argCBH messenger ribonucleic acid. The specific regulation of these operons by the arginine holorepressor was demonstrated, providing evidence that the majority, if not all, of the control of these operons is exercised at the transcriptional level. Data are presented which indicate that the arginine holorepressor functions by binding to the operator region and concomitantly prevents the binding of ribonucleic acid polymerase to the corresponding promoter region.
Isolation and characterization of nuclei from Neurospora crassa
Authors: Hautala J A , Conner B H , Jacobson J W , Patel G L , Giles N H
Published: January 2020

A procedure was developed for isolating nuclei from either the conidial or germinated conidial growth phase of Neurospora crassa. A frozen conidial suspension was lysed by passage through a French pressure cell, and the nuclei were freed from the broken cells by repeated homogenization in an Omni-Mixer. Pure nuclei were obtained from the crude nuclear fraction by density banding in a Ludox gradient. The final nuclear yield was 20 to 30%. The nuclei had a deoxyribonucleic acid (DNA):ribonucleic acid (RNA):protein ratio of 1:3.5:7 and were active in RNA synthesis. The nuclei, stained with the DNA stain 4,6-diamidino-2-phenylindole, appeared under fluorescence microscopy as bright blue spheres, 1 micron in diameter, essentially free from cytoplasmic attachments. Chromatin extracted from the nuclei in a 70 to 75% yield by dissociation with 2 M sodium chloride and 5 M urea had a DNA:RNA:protein ratio of 1:1.05:1.7. Chromatin reconstituted from this preparation exhibited a level of RNA polymerase template activity lower than that of pure Neurospora DNA, but the maximum level of reconstitution obtained was only 10%. Fractionation of Neurospora chromatin on hydroxylapatite separated the histones from the chromatin acidic proteins. The normal complement of histone proteins was present in both the reconstituted and dissociated chromatin preparations. The acidic protein fraction exhibited a variety of bands on sodium dodecyl sulfate gel electrophoresis ranging in molecular weight from 15,000 to 70,000. The gel pattern was much more complex for total dissociated chromatin than for reconstituted chromatin.
Amino acid transport and metabolism in nitrogen-starved cells of Saccharomyces cerevisiae
Authors: Woodward J R , Cirillo V P
Published: January 2020

Nitrogen-starved yeast derepress a general amino acid permease which transports basic and hydrophobic amino acids. Although both groups of amino acids are metabolized, the derivatives of the basic amino acids are retained by the cells, whereas those of the hydrophobic amino acids are released as acidic and neutral deaminated derivatives. The release of the deaminated derivatives of the hydrophobic amino acids only occurs in the presence of glucose, which presumably produces amino acceptors. The accumulation of intracellular amino acids results in trans-inhibition of the uptake of exogenous amino acids whether the intracellular amino acid is a basic amino acid or the product of intracellular transamination from a hydrophobic amino acid. Variation of permease and transaminase activity was measured during growth under repressed (ammonia-grown) and derepressed (proline-grown) conditions. Maximum levels for both activities occurs at the mid-exponential phase.
Flagellar formation in Escherichia coli electron transport mutants
Authors: Bar Tana J , Howlett B J , Koshland D E
Published: January 2020

Mutants of Escherichia coli lacking ubiquinone or heme have been tested for motility and found to be essentially immotile. The loss of motility is identified with the loss of flagellum synthesis.
Two pools of glycogen in Saccharomyces
Authors: Gunja-Smith Z , Patil N B , Smith E E
Published: January 2020

The effect of different extraction procedures on the yields of water-soluble and water-insoluble glycogen fractions from a number of Saccharomyces strains was studied by using a specific method for glycogen determination. The similarity of the yields obtained by the different procedures showed that neither form of glycogen is an artifact, and variations in the relative amounts of glycogen in the two fractions during cell growth and in different yeast strains suggest that they represent different pools of storage material with specific roles in cell development and differentiation. A proportion of the water-insoluble glycogen fraction, solubilized by mechanical agitation, was shown to be strongly associated with a beta-glucan-like polysaccharide that may be a cell wall component.
Regulatory changes in the fucose system associated with the evolution of a catabolic pathway for propanediol in Escherichia coli
Authors: Hacking A J , Lin E C
Published: January 2020

Wild-type strains of Escherichia coli are unable to use L-1,2-propanediol as a carbon and energy source. Strain 3, a mutant selected for the ability to grow on this compound at progressively more rapid rates, synthesizes constitutively a nicotinamide adenine dinucleotide-linked propanediol oxidoreductase. This enzyme is normally synthesized during anaerobic growth on L-fucose when it functions as a lactaldehyde reductase. Propanediol, the end product of this fermentation process, escapes irretrievably into the medium. The propanediol-utilizing mutant can no longer grow on fucose in either the presence or absence of molecular oxygen. In the present study nine independent lines of propanediol-positive mutants were characterized. One mutant, strain 418, attained a propanediol growth rate close to that of strain 3 without loss of the ability to grow on fucose. In all cases examined, however, prolonged selection on propanediol did result in the emergence of fucose-negative mutants. All of these mutants had enzyme patterns similar to that of strain 3; namely, fucose permease, fucose isomerase, and fuculose kinase were noninducible, whereas fuculose 1-phosphate aldolase was constitutive. In strain 418 and in the fucose-positive predecessors of the other mutants, the first four enzymes in the pathway remained inducible, as in the wild-type strain. Improvements in the growth rate on propanediol appeared to reflect principally the increased activity level of the oxidoreductase during the early stages of evolution. According to transductional analysis, the mutations affecting the ability to grow on propanediol and those that affect the expression of the first enzymes in the fucose pathway were very closely linked. The loss of the ability to grow on fucose is thought to be a mechanistic consequence incidental to the remodeling of the regulatory system in favor of the utilization of the novel carbon source.
Multivalent regulation of isoleucine-valine transaminase in an Escherichia coli K-12 ilvA deletion strain
Authors: Kline E L , Manross D N , Warwick M L
Published: January 2020

In a strain of Escherichia coli K-12 lacking threonine deaminase, the enzyme converting alpha-ketoisovalerate and alpha-keto-beta-methylvalerate to valine and isoleucine, respectively, was multivalently repressed by valine, isoleucine, and leucine. This activity was due to transaminase B, specified by the ilvE structural gene.
Genetic loci of hemolysin production in Streptococcus faecalis subsp. zymogenes
Authors: Frazier M L , Zimmerman L N
Published: January 2020

Two plasmids corresponding to molecular weights of 38.5 X 10(6) and 3.6 X 10(6) have been identified in Streptococcus faecalis subsp. zymogenes strain X-14. The larger plasmid is required for hemolysin-bacteriolysin production. Strain L2, a nonlytic nitrosoquanidine mutant of strain X-14, still harbors the hemolytic plasmid and produces the lysin component, but not the activator component, of the lytic system. Conjugal transfer of this plasmid from strain L2 to plasmid-free strains and strains cured of the 38.5-megadalton plasmid gives rise to hemolytic recipients. This implicates a gene in hemolysin production at a site other than the 38.5-megadalton plasmid.
Distribution of xanthine oxidase and xanthine dehydrogenase specificity types among bacteria
Authors: Woolfolk C A , Downard J S
Published: January 2020

A diverse collection of xanthine-metabolizing bacteria was examined for xanthine-, 1-methylxanthine-, and 3-methylxanthine-oxidizing activity. Both particulate and soluble fractions of extracts from aerobically grown gram-negative bacteria exhibited oxidation of all three substrates; however, when facultative gram-negative bacteria were grown anaerobically, low particulate and 3-methylxanthine activities were detected. Gram-positive and obligately anaerobic bacteria showed no particulate activity or 3-methylxanthine oxidation. Substrate specificity studies indicate two types of enzyme distributed among the bacteria along taxonomic lines, although other features indicate diversity of the enzyme within these two major groups. The soluble and particulate enzymes from Pseudomonas putida and the enzyme from Arthrobacter S-2 were examined as type examples with a series of purine and analogues differing in the number and position of oxygen groups. Each preparation was active with a variety of compounds, but the compounds and position attacked by each enzyme was different, both from the other enzymes examined and from previously investigated enzymes. The soluble enzyme from Pseudomonas was inhibited in a competitive manner by uric acid, whereas the Arthrobacter enzyme was not. This was correlated with the ability of Pseudomonas, but not Arthrobacter, to incorporate radioactivity from [2-14C]uric acid into cellular material.
Analysis of genetic recombination between two partially deleted lactose operons of Escherichia coli K-12
Authors: Zieg J , Kushner S R
Published: January 2020

Genetic recombination between a nontandem duplication of two partially deleted lactose operons (lacMS286phi80dIIlacBK1) in Escherichia coli K-12 has been examined. Since the deletions were nonoverlapping, rare lactose-fermenting (Lac+) recombinants occurred and were detected qualitatively on lactose tetrazolium agar indicator plates as white papillae growing on the surface of red colonies or quantitively on lactose minimal agar plates. Formation of Lac+ recombinants required the recA, recB, and recC gene products. Indirect suppression of recB21 by sbcB15 led to an increase in the frequency of Lac+ recombinants over wild-type levels. recF143 did not appreciably alter the number of Lac+ progeny, whereas recL152 and sbcB15 strains yielded increased numbers of Lac+ recombinants. The nature and formation of Lac+ recombinants was also examined. Respreading analysis indicated that formation of recombinants occurred primarily as the cells entered early stationary phase on the surface of the minimal agar plates and that over 90% of the recombinants contained a phi80dIIlac+ prophage. Time-of-entry experiments suggested that the region of deoxyribonucleic acid between the two operons was not inverted as a result of the recombinational event.
Messenger ribonucleoprotein complexes isolated by oligodeoxythymidylate-cellulose chromatography from Neurospora crassa polysomes
Authors: Mirkes P E
Published: January 2020

Messenger ribonucleoprotein (mRNP) complexes were isolated from ethylenediaminetetraacetic acid-dissociated polysomes of Neurospora crassa. Approximately 15% of the [3H]uridine incorporated into polysomal ribonucleic acid (RNA) during a 15-min pulse was eluted from oligodeoxythymidylate-cellulose as an mRNP complex. The isolated mRNP complexes exhibited sedimentation coefficients ranging from 15S to greater than 60S. RNA isolated from these mRNP complexes sedimented in sucrose gradients between 4S and 40S, with broad peaks at 15S and 24S. The buoyant density of mRNP complexes eluted with 25% formamide was 1.42 to 1.44 g/cm3, whereas for mRNP complexes eluted with 50% formamide it was 1.48 to 1.50 g/cm3. Six polypeptides, with molecular weights of 14,000, 19,000, 24,000, 31,000, 44,000, and 66,000, were associated with mRNP complexes eluted with 25% formamide. The mRNP complexes eluted with 50% formamide had one associated polypeptide, of molecular weight 27,000.
Composition and molecular weight of pili purified from Pseudomonas aeruginosa K
Authors: Frost L S , Paranchych W
Published: January 2020

Pseudomonas aeruginosa strain K (PAK) bears polar pili that promote infection by at least six bacteriophages. Moreover, a recently isolated mutant of strain K (PAK/2PfS) is many times more piliated than the wild-type strain and facilitates the preparation of large amounts of pure pili for biochemical studies. The present investigation was carried out to establish the structural relatedness of PAK and PAK/2PfS pili and to determine their biochemical composition. A purfication procedure is described for PAK and PAK/2PfS pili that yields about 8 mg of pure pili per 100 g (wet weight) of PAK/2PfS cells and 0.8 mg of pure pili per 100 g (wet weight) of PAK cells. PAK and PAK/2PfS pili were found to be free from phosphate, carbohydrate, and lipid and to contain a single polypeptide subunit of 17,800 daltons. Isopycnic centrifugation studies revealed that PAK and PAK(2PfS pili have the same buoyant density in sucrose (1.221) and CsC1 (1.295). Both types of pili banded at pH 3.9 when subjected to isoelectric focusing. Amino acid analyses showed that PAK and PAK/2PfS pili have identical amino acid compositions, whereas microimmunodiffusion studies revealed that the two types of pili are immunologically indistinguishable. It was concluded that PAK and PAK/2PfS pili are identical and that the mutation responsible for producing the multipiliated state in PAK/2PfS is probably located outside the structural gene for PAK pili.
Genetics of the relB locus in Escherichia coli
Authors: Diderichsen B , Fiil N P , Lavallé R
Published: January 2020

A mutant of Escherichia coli with a delayed relaxed phenotype very similar to that of a previously described relB mutant has been obtained using a new selection procedure. The mutation giving rise to this phenotype has been shown to map at 34.5 min and to be 12% cotransducible with man. It is recessive, revertible, and most likely an allele of the relB gene.
Fructose 1,6-diphosphate-activated L-lactate dehydrogenase from Streptococcus lactis: kinetic properties and factors affecting activation
Authors: Crow V L , Pritchard G G
Published: January 2020

The L-(+)-lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) of Streptococcus lactis C10, like that of other streptococci, was activated by fructose 1,6-diphosphate (FDP). The enzyme showed some activity in the absence of FDP, with a pH optimum of 8.2; FDP decreased the Km for both pyruvate and reduced nicotinamide adenine dinucleotide (NADH) and shifted the pH optimum to 6.9. Enzyme activity showed a hyperbolic response to both NADH and pyruvate in all the buffers tried except phosphate buffer, in which the response to increasing NADH was sigmoidal. The FDP concentration required for half-maximal velocity (FDP0.5V) was markedly influenced by the nature of the assay buffer used. Thus the FDP0.5V was 0.002 mM in 90 mM triethanolamine buffer, 0.2 mM in 90 mM tris(hydroxymethyl)aminomethanemaleate buffer, and 4.4 mM in 90 mM phosphate buffer. Phosphate inhibition of FDP binding is not a general property of streptococcal lactate dehydrogenase, since the FDP0.5V value for S. faecalis 8043 lactate dehydrogenase was not increased by phosphate. The S. faecalis and S. lactis lactate dehydrogenases also differed in that Mn2+ enhanced FDP binding in S. faecalis but had no effect on the S. lactis dehydrogenase. The FDP concentration (12 to 15 mM) found in S. lactis cells during logarithmic growth on a high-carbohydrate (3% lactose) medium would be adequate to give almost complete activation of the lactate dehydrogenase even if the high FDP0.5V value found in 90 mM phosphate were similar to the FDP requirement in vivo.
Effect of light on Bdellovibrio bacteriovorus
Authors: Friedberg D
Published: January 2020

Bdellovibrio underwent photooxidation by visible light in the presence of exogenous photosensitizer and by near-ultraviolet light (325 to 400 nm) in its absence. The colorless, host-dependent wild type was more sensitive to the lethal effect of light than was its pigmented, facultative parasitic mutant. The latter's ability to form colonies was much more sensitive to light than was its plaque-forming capability. The biosynthesis of the mutant pigment was inhibited by diphenylamine, though this inhibition did not result in additional sensitivity to photokilling.
Function of cell wall teichoic acid in thermally injured Staphylococcus aureus
Authors: Hoover D G , Gray R J
Published: January 2020

Thermally injured cells of Staphylococcus aureus lack the ability to grow on tryptic soy agar containing 7.5% NaCl. This injury phenomenon was examined in three strains of S. aureus: MF-31; H (Str); and, isolated from H (Str), 52A5, a mutant which lacks teichoic acid in the cell wall. Temperatures for sublethal heat treatment were selected to produce maximum injury with minimum death for each strain. Examination of isolated cell walls showed that magnesium was lost from the wall during heating, and that the degree of cell injury was accentuated when magnesium ions were either removed from or made unavailable to the cell. S. aureus 52A5 was more heat sensitive than its parent strain. Cells containing higher levels of wall teichoic acid generally showed less injury than normal cells. Cells with the weaker cation-binding polymer, teichuronic acid, in the cell wall generally showed greater injury. These data suggest that cell wall teichoic acid of S. aureus aids in the survival of the cell by the maintenance of an accessible surface pool of magnesium.
Two systems for the uptake of phosphate in Escherichia coli
Authors: Rosenberg H , Gerdes R G , Chegwidden K
Published: January 2020

Mutants of Escherichia coli K-12 were constructed such that each possessed one single major system for phosphate transport. A comparison of these strains showed that one of the systems (PIT) was fully constitutive, required no binding protein, and operated in spheroplasts. It permitted the complete exchange of intracellular phosphate with extracellular phosphate (or arsenate) and was completely inhibited by uncouplers. The other system, PST, was repressible by phosphate concentrations above 1 mM, required the phosphate-binding protein for full activity, and did not operate in spheroplasts. It catalyzed very little exchange between internal and external phosphate and was resistant to uncouplers. The maximal velocities attained by the two systems were approximately the same, but the affinity for phosphate in the PST system was greater by two orders of magnitude. In strains in which both systems were fully operative, the initial rates of uptake was nearly additive, and the systems appeared to interact with a common intracellular phosphate pool.
Intracellular localization of the superoxide dismutases of Escherichia coli: a reevaluation
Authors: Britton L , Fridovich I
Published: January 2020

All of the superoxide dismutase isozymes of Escherichia coli have been shown to occur in the cell matrix, and none have been found in the periplasm. This was the case with both E. coli B and E. coli K-12, whether grown on a low phosphate medium or on a Trypticase soy-yeast extract medium. Alkaline phosphatase was used as a marker of the periplasm; adenosine deaminase and glucose 6-phosphate dehydrogenase were used as matrix markers, and consistent results were obtained by osmotic shock, spheroplast formation, and use of a diazonium salt that penetrates the periplasm but cannot cross the plasma membrane. A previous report that the iron-containing superoxide dismutase of E. coli is a periplasmic enzyme is now seen to have been in error.
Glutamate transport driven by an electrochemical gradient of sodium ions in Escherichia coli
Authors: Tsuchiya T , Hasan S M , Raven J
Published: January 2020

The role of Na+ in glutamate transport was studied in Escherichia coli B, strain 29-78, which possesses a very high activity of glutamate transport (L. Frank and I. Hopkins, J. Bacteriol., 1969). Energy-depleted cells were exposed to radioactive glutamate in the presence of a sodium gradient, a membrane potential, or both. One hundred- to 200-fold accumulation of the amino acid was attained in the presence of both electrical and chemical driving forces for the sodium ion. Somewhat lower accumulation values were obtained when either chemical or electrical driving forces were applied separately. A chemical driving force was produced by the addition of external Na+ to Na+-free cells. A membrane potential was established by a diffusion potential either of H+ in the presence of carbonyl cyanide p-trifluoromethoxyphenylhydrazone or of SCN-. These results support the hypothesis of a Na+-glutamate cotransport. Na+-driven glutamate transport was also observed in wild-type E. coli B but not in a strain of K-12.
Specific alteration of the 30S ribosomal subunits of Bacillus subtilis during sporulation
Authors: Guha S , Szulmajster J
Published: January 2020

Active 30S ribosomal subunits were isolated from vegetative and sporulating cells of Bacillus subtilis. Both subunits were able to function in polyuridylic acid of phage phie messenger ribonucleic acid-dependent protein synthesis in vitro. The sporulation 30S subunits were highly active in polyuridylic acid-dependent polyphenylalanine synthesis but showed a reduced activity in the presence of natural messenger ribonucleic acid as compared with their vegetative counter-parts. The reduced activity was independent of the source of 50S particles and initiation factors (vegetative or sporulation). The alteration of the 30S sporulation subunits appears to be related to the sporulation process, since the same subunits isolated from stationary-phase cells of an asporogenic mutant did not show any impairment in protein synthesis in vitro.
Isolation and characterization of fusidic acid-resistant, sporulation-defective mutants of Bacillus subtilis
Authors: Kobayashi H , Kobayashi K , Kobayashi Y
Published: January 2020

Fusidic acid-resistant, sporulation-defective mutants were isolated from Bacillus subtilis 168 thy trp. About two-thirds of the fusidic acid-resistant (fusr) mutants were defective in sporulation ability and fell into three classes with respect to sporulation character. The representative mutants FUS426 and FUS429 were characterized in detail. FUS426 [fusr spo (Ts)], a temperature-sensitive sporulation mutant, grew well at 30 and 42 degrees C but did not sporulate at 42 degrees C. FUS429 [fusr spo (Con)], conditional sporulation mutant, grew and sporulated normally in the absence of fusidic acid, but its sporulation and growth rates decreased in the presence of fusidic acid, depending on the concentration of the drug. Although electron microscopic observation showed that both mutants were blocked at stage I of sporulation, the physiological analyses indicate that these mutants belong to the SpoOB class. Both mutants formed a thickened cell wall as compared with that of the parental strain. Genetic and in vitro protein synthesis analyses led to the conclusion that the sporulation-defective character of mutants FUS426 and FUS429 resulted from an alteration in elongation factor G caused by a single lesion in the fus locus. The possible role of elongation factor G in sporulation is discussed.
Envelope-associated nucleoid from Caulobacter crescentus stalked and swarmer cells
Authors: Evinger M , Agabian N
Published: January 2020

Envelope-associated nucleoids have been isolated from Caulobacter crescentus by using a modification of the procedure of T. Kornberg et al. (Proc. Natl. Acad. Sci. U.S.A. 71:3189-3193, 1974). The development of a Ludox density gradient procedure has permitted preparation of large quantities of synchronous cells. The sedimentation coefficients of the envelope-associated nucleoids of stalked and swarmer cells, prepared under conditions of equivalent cell lysis, were 3,000S and greater than 6,000S respectively. Small differences in the relative amounts of deoxyribonucleic acid, ribonucleic acid, and protein in stalked and swarmer cell envelope-associated nucleoids could not account for the large differences in sedimentation behavior. These characteristic sedimentation coefficients were retained in mixing experiments.
Studies of colicin E1 plasmid functions by analysis of deletions and TnA insertions of the plasmid
Authors: Inselburg J
Published: January 2020

The further identification of regions of the colicin E1 plasmid that affect plasmid functions has been achieved by studying deletions and TnA insertions of the plasmid. Colicin production, colicin immunity, relaxation of plasmid deoxyribonucleic acid, and plasmid incompatibility functions have been examined. A strong correlation has been observed between the ability of colicin E1 plasmid deoxyribonucleic acid to be relaxed and the ability of that plasmid to be transferred by conjugation.
Localized mutagenesis with bacteriophage Mu: method for increasing the frequency of specific bacterial mutants
Authors: Tabor H , Hafner E W , Tabor C W
Published: January 2020

A method is described for markedly enriching a bacterial population for cells containing any given Mu insertion mutation. The method involves the transfer of a small piece of deoxyribonucleic acid from a Mu-infected Hfr donor donor strain to a suitable F- strain and a subsequent selection of those recombinant organisms that have received a Mu prophage from the donor. The method is particularly usefule for isolating mutants whose selection requires "brute-force" assay, since only a few hundred colonies have to be screened.
Lipiarmycin-resistant ribonucleic acid polymerase mutants of Bacillus subtilis
Authors: Sonenshein A L , Alexander H B , Rothstein D M , Fisher S H
Published: January 2020

Lipiarmycin inhibited the activity of deoxyribonucleic acid-dependent ribonucleic acid (RNA) polymerase in vitro. We showed that inhibition was due to interference by lipiarmycin with the activity of sigma-containing molecules of RNA polymerase. Transcription by core enzyme was relatively resistant to the drug, but addition of sigma led to highly drug-sensitive RNA synthesis. We isolated lipiarmycin-resistant mutants of Bacillus subtilis and characterized them genetically and biochemically. Drug-resistant mutants contained an altered RNA polymerase that was resistant to the drug in vitro. By separation and mixed reconstitution of core and sigma fractions of mutant and wild-type RNA polymerase, we showed that lipiarmycin resistance in one mutant strain was a property of the core fraction. Genetic mapping experiments indicated that at least two lpm mutants are located between loci determining rifampin resistance and streptolydigin resistance.
Pseudomonas aeruginosa mutants resistant to urea inhibition of growth on acetanilide
Authors: Gregoriou M , Brown P R , Tata R
Published: January 2020

Pseudomonas aeruginosa AI 3 was able to grow in medium containing acetanilide (N-phenylacetamide) as a carbon source when NH4+ was the nitrogen source but not when urea was the nitrogen source. AIU mutants isolated from strain AI 3 grew on either medium. Urease levels in bacteria grown in the presence of urea were 10-fold lower when NH4+ or acetanilide was also in the medium, but there were no apparent differences in urease or its synthesis between strain AI 3 and mutant AIU 1N. The first metabolic step in the acetanilide utlization is catalyzed by an amidase. Amidases in several AIU strains showed altered physiochemical properties. Urea inhibited amidase in a time-dependent reaction, but the rates of the inhibitory reaction with amidases from the AIU mutants were slower than with AI 3 amidase. The purified amidase from AIU 1N showed a marked difference in its pH/activity profile from that obtained with purified AI 3 amidase. These observations indicate that the ability of strain AIU 1N and the other mutants to grow on acetanilide/urea medium is associated with a mutation in the amidase structural gene; this was confirmed for strain AIU 1N by transduction.
Evidence for a complex of three beta-oxidation enzymes in Escherichia coli: induction and localization
Authors: O'Brien W J , Frerman F E
Published: January 2020

The enzymes for beta-oxidation of fatty acids in inducible and constitutive strains of Escherichia coli were assayed in soluble and membrane fractions of disrupted cells by using fatty acid and acyl-coenzyme A (CoA) substrates containing either 4 or 16 carbon atoms in the acyl moieties. Cell fractionation was monitored, using succinic dehydrogenase as a membrane marker and glucose 6-phosphate dehydrogenase as a soluble marker. Acyl-CoA synthetase activity was detected exclusively in the membrane fraction, whereas acyl-CoA dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase, enoyl-CoA hydratase, and 3-ketoacyl-CoA thiolase activities that utilized both C4 and C16 acyl-CoA substrates were isolated from the soluble fraction. 3-Hydroxyacyl-CoA dehydrogenase, enoyl-CoA hydratase, and 3-ketoacyl-CoA thiolase activities assayed with both C4 and C16 acyl-CoA substrates co-chromatographed on gel filtration and ion-exchange columns and cosedimented in glycerol gradients. The data show that these three enzyme activities of the fad regulon can be isolated as a multienzyme complex. This complex dissociates in very dilute preparations; however, in those preparations where the three activities are separated, the fractionated species retain activity with both C4 and C16 acyl-CoA substrates.
Cleavage of adenosine 5'-monophosphate during uptake by Streptomyces griseus
Authors: Martin J F , Demain A L
Published: January 2020

Unlabeled adenine brought about a (delayed) decrease in radioactivity that had been taken up by phosphate-limited resting cells of Streptomyces griseus from [14C]adenine-labeled adenosine 5'-monophosphate (AMP). Inorganic phosphate, on the other hand, stimulated adenine uptake from AMP, presumably by activating an energy-dependent active transport mechanism. Unlabeled phosphate rapidly diluted the uptake of radioactivity from [32P]AMP. Adenine inhibited uptake of [32P]AMP but not that of [32P]orthophosphate; adenine is thought to act by inhibiting the cleavage of AMP. The uptake of 32P and 14C from double-labeled AMP showed marked differences; 32P was taken up much faster into both cells and nucleic acids. These data indicate that uptake of AMP components takes place after extracellular dephosphorylation of the nucleotide.
Purification and partial characterization of the principal deoxyribonucleic acid polymerase from Mycoplasmatales
Authors: Mills L B , Stanbridge E J , Sedwick W D , Korn D
Published: January 2020

In this report we present the first description of the isolation and partial characterization of the deoxyribonucleic acid (DNA) polymerase activity from two species of Mycoplasmatales, Mycoplasma orale type 1 and M. hyorhinis. We have identified only a single DNA polymerase species in the mycoplasma crude extracts, and the enzymes from the two organisms are very similar in their structural and enzymatic properties. The purified polymerase from each source has a specific activity of greater than 50,000 U/mg of protein, a sedimentation coefficient of 5.6s, and an estimated molecular weight by gel filtration of 130,000. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the most highly purified M. orale fraction contains a single major protein band of 130,000 daltons, which we believe may represent the polymerase protein. The enzymes are most reactive with gapped (activated) DNA and show a marked preference for this primer template over oligodeoxyribonucleotide-initiated homoribo- or homodeoxyribo-polymers. The most purified preparations are devoid of contaminating endonuclease activity and also appear to lack associated 5' leads to 3'- or 3' leads to 5'-exonuclease activities, as determined by highly sensitive assays. The absence of the 3' leads to 5'-exonuclease is particularly remarkable in that this activity is essentially ubiquitous among the DNA polymerases that have thus far been characterized from procaryotes.
Molecular basis for the maximum growth temperature of an obligately psychrophilic yeast, Leucosporidium stokesii
Authors: Silver S A , Yall I , Sinclair N A
Published: January 2020

Cells of the obligately psychrophilic yeast Leucosporidium stokesii were subjected to permissive (15 and 20 degrees C) and restrictive (23 and 25 degrees C) temperatures to determine the event(s) responsible for the low maximum growth temperature of this organism. An investigation of subcellular morphology by nuclear staining revealed that buds formed at 20 degrees C were anucleate but showed nuclear migration within the parent cell. Cells incubated initially at 23 degrees C and then shifted down to a permissive growth temperature of 15 degrees C in the presence of a deoxyribonucleic acid (DNA) synthesis inhibitor, hydroxyurea, confirmed the observation that the anucleate condition of atypical buds was the result of temperature-sensitive DNA synthesis. Concomitantly, the incorporation of labeled adenine into DNA was inhibited at 23 and 25 degrees C. The synthesis of ribonucleic acid, however, was enhanced at 23 degrees C but impaired at 25 degres C. Similarly, protein synthesis was unaffected at either restrictive temperature.
Revised Interpretation of the Origin of the pSC101 Plasmid
Authors: Cohen Stanley N. , Chang Annie C. Y.
Published: January 2020

Data are presented indicating that the pSC101 plasmid was not derived by recircularization of a mechanically sheared fragment of R6-5 plasmid deoxyribonucleic acid, as was originally believed.
Production of large amounts of acetate during germination of Bacillus megaterium spores in the absence of exogenous carbon sources
Authors: Setlow B , Shay L K , Vary J C , Setlow P
Published: January 2020

When Bacillus megaterium spores germinate in the absence of an exogenous carbon source, the first minutes of germination are accompanied by production of large amounts (approximately 70 nmol/mg of dry spores) of acetate and much smaller amounts of pyruvate and lactate. The majority of these compounds are excreted into the medium. Exogenous pyruvate and alanine are also converted to CO2 and acetate by germinating spores, presumably by using the pyruvate dehydrogenase that is present in dormant spores. These data suggest that the 3-phosphoglyceric acid stores in the dormant spore and alanine generated by proteolysis early in germination can be catabolized to acetate during germination with production of large amounts of reduced nicotinamide adenine dinucleotide, acetyl coenzyme A, and adenosine 5'-triphosphate.
Outer membranes of gram-negative bacteria. XV. Transmembrane diffusion rates in lipoprotein-deficient mutants of Escherichia coli
Authors: Nikaido H , Bavoil P , Hirota Y
Published: January 2020

Permeability of the outer membrane to 6-aminopenicillanic acid was unaltered in an lpo mutant, lacking the Braun lipoprotein, a result suggesting that the lipoproteins by themselves form no or few diffusion pores.
Identification of the structural gene for the hook subunit protein of Escherichia coli flagella
Authors: Komeda Y , Silverman M , Simon M
Published: January 2020

Previous studies showed that the structural gene for the flagellar hook subunit protein (molecular weight 42,000) was one of a group of flagellar genes located on the Escherichia coli genome near pyrC. Several lines of evidence indicate that the flaK gene is the structural gene for the hook subunit protein. Fla+ strains that were insensitive to chi infection could be isolated as revertants of an FlaK- amber mutant strain but from no other Fla- strain. The hook subunit proteins isolated from such chi-sensitive revertants of the FlaK- strain were shown to be antigenically and electrophoretically different from the hook protein isolated from the wild-type strain. Thus, reversion of a mutation in the flaK gene resulted in alteration of the structure of the hook protein. Furthermore, in programming experiments with hybrid lambda containing flagellar genes, lambdafla with flaK genetic activity programmed the synthesis of a 42,000-molecular weight protein, whereas lambdafla without flaK genetic activity did not.
Gene dosage effects of the structural gene for a lipoprotein of the Escherichia coli outer membrane
Authors: Movva N R , Katz E , Asdourian P L , Hirota Y , Inouye M
Published: January 2020

The gene dosage effects of the structural gene (lpp) for the lipoprotein of the Escherichia coli outer membrane were examined. A novel F-prime factor containing the lpp gene was constructed. The amount of the free-form lipoprotein in the merodiploid strain carrying the F-prime factor was found to be about two times as great as that in the corresponding haploid strain. On the other hand, the amount of the bound-form lipoprotein, which is vovalently linked to the peptidoglycan, was not significantly different in the merodiploid strain as compared with the corresponding haploid strain. The present results suggest that the lpp gene is expressed constitutively in contrast to another major protein of the E. coli outer membrane, tolG protein (protein II, D. B. Datta et al., J. Bacteriol. 128:834-841, 1976). The F-prime factor isolated may include a portion of the E. coli chromosome (located between 33 and 36 min on the genetic map) that is not covered by any other F-prime factor.
Evidence that glucose starvation-sensitive mutants are altered in the relB locus
Authors: Mosteller R D
Published: January 2020

Genetic mapping studies indicate that the relaxed-control mutants isolated on the basis of sensitivity to glucose starvation contain lesions in the relB locus. These mutants, which are sensitive to protein synthesis inhibitors such as sulfacetamide, exhibit relaxed control of both RNA and phospholipid syntheses.
Changes in cell size and shape in thymine-requiring Escherichia coli associated with growth in low concentrations of thymine
Authors: Begg K J , Donachie W D
Published: January 2020

Thymine auxotrophs of three unrelated strains of Escherichia coli (K-12, B/r, and 15) were grown in media containing various concentrations of thymine. During steady-state growth conditions, cell volume increased as thymine concentration decreased but, in contrast to previous reports, this change was due to an increase in cell length without change in cell diameter.
Comparative immunological studies on arylsulfatase in bacteria of the family Enterobacteriaceae: occurrence of latent arylsulfatase protein regulated by sulfur compounds and tyramine
Authors: Yamada T , Murooka Y , Harada T
Published: January 2020

The arylsulfatases of 21 strains of the family Enterobacteriaceae were compared by measuring their enzymatic activities and immunological reactivities. Enzyme formation under repressing, nonrepressing, and derepressing conditions was tested. Antiserum prepared against pure arylsulfatase from Klebsiella aerobgenes W70 was tested against the enzyme extracts from the strains using double diffusion, quantitative precipitation, and immunoelectrophoresis. No close relationship was found between arylsulfatase activity and immunological cross-reactionship was found between arylsulfatase activity and immunological cross-reactivity. The strains in the family Enterobacteriaceae could be divided into two groups on the basis of the immunological properties of their enzyme. Antisera formed a precipitin band with both active and inactive enzyme proteins from Escherichia, Citrobacter, Salmonella, Klebsiella, and Enterobacter, but not with the proteins from Serratia, Proteus, and Erwinia, even though some strains of these species had enzyme activity. It was also found that the formation of arylsulfatase proteins, irrespective of whether they had enzyme activity, were under regulation by sulfur compounds and tyramine.