bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen-dependent inactivation of gramicidin S synthetase in Bacillus brevis
Authors: Friebel T E , Demain A L
Published: January 2020

Incorporation of L-[14C]ornithine into gramicidin S by crude, unfractionated lysozyme extracts of Bacillus brevis ATCC 9999 was shown to represent the activity of the gramicidin synthetase complex. Frozen-thawed cells were the source of active extracts, but when cells were shaken in air at 37 degrees C, they rapidly lost activity in a first-order reaction with a half-life of 13 min. Protease inhibitors and inhibitors of energy metabolism had no effect on the inactivation process in frozen-thawed cells. Stabilization was achieved when the cells were shaken in nitrogen or helium instead of air. The addition of dithiothreitol produced a moderate degree of stabilization. The L-ornithine- and D-phenylalanine-activating activities of the gramicidin S synthetase complex were also lost during aeration of the cells. Crude cell-free extracts also lost activity when they were shaken in oxygen, but, in this case, inactivation was slower (half-life of 80 min). Nitrogen also stabilized these cell-free extracts.
Lysogenic Conversion for Multiple Characters in a Strain of
Staphylococcus aureus
Authors: Duval-Iflah Yvonne , Van Heijenoort Jean , Rousseau Micheline , Raibaud Pierre
Published: January 2020

Lysogenization of nonlysogenic strains of
Staphylococcus aureus
was performed with two different bacteriophages, LS1 and LS2, that were unable to plaque on any of the strains of
S. aureus
tested. Infection of recipient strains was achieved when protoplasts were inoculated with LS1 or LS2 or when bacterial cultures were simultaneously inoculated with a virulent phage together with LS1 or LS2. Lysogenization was demonstrated by changes in phenotypic characters of the host strain and by liberation of bacteriophages from the modified strains as shown by electron microscopic examination. The lysogenic strains differed from the host strains by the following characters: they were coagulase, deoxyribonuclease, and lipase negative; they were untypable by the basic set of phages; they did not ferment mannitol under anaerobic conditions; and they produced only
l
-(+)-lactic acid by glucose fermentation. Their cell walls contained less glycine and concomitantly more serine than those of the host strains. Furthermore, they were devoid of protein A. Conversely, some antigenic factors as well as the presence of ribitol in the cell wall teichoic acid, indicated a parental relationship between the host strains and the derived lysogenic ones. Phages LS1 and LS2 could be excluded from the lysogenic strains by invading phages, and the revertant nonlysogenic strains recovered all of the characteristics of the initial host strains. It was thus concluded that the phenomenon described was due to lysogenic conversion. The origin of phages LS1 and LS2 is discussed.
Control of Arylsulfatase in a Serine Auxotroph of
Neurospora
Authors: Jacobson Eric S. , Metzenberg Robert L.
Published: January 2020

A serine auxotroph of
Neurospora
requires exogenous serine to repress the arylsulfatase, suggesting that this enzyme is repressed by cysteine and not by methionine.
Characterization of methylated neutral amino acids from Escherichia coli ribosomes
Authors: Chang F N , Budzilowicz C
Published: January 2020

The methylated neutral amino acids from both 30S and 50S ribosomal subunits of an Escherichia coli K strain were characterized. The 50S ribosomal subunit contains three methylated neutral amino acids: N-monomethylalanine, N-monomethylmethionine, and an as yet unidentified methylated amino acid found in protein L11. Both N-monomethylalanine and N-monomethylmethionine were found in protein L33. The amount of N-monomethylmethionine in this protein, however, is variable but not more than 0.25 molecules per protein. Thus protein L33 from this E. coli K strain has heterogeneity in its N-terminal amino acid and can start with either N-monomethylalanine or N-monomethylmethionine. The N-monomethylmethionine residue was not derived from the reduction of N-formylmethionine in the protein. The 30S ribosomal subunit contains only one methylated neutral amino acid: N-monomethylalanine.
Glucose catabolism in two derivatives of a Rhizobium japonicum strain differing in nitrogen-fixing efficiency
Authors: Mulongoy K , Elkan G H
Published: January 2020

Radiorespirometric and enzymatic analyses reveal that glucose-grown cells of Rhizobium japonicum isolates I-110 and L1-110, both derivatives of R. japonicum strain 3I1b110, possess an active tricarboxylic acid cycle and metabolize glucose by simultaneous operation of the Embden-Meyerhof-Parnas and Entner-Doudoroff pathways. The hexose cycle may play a minor role in the dissimilation of glucose. Failure to detect the nicotinamide adenine dinucleotide phosphate-dependent decarboxylating 6-phosphogluconate dehydrogenase (EC 1.1.1.44) evidences absence of the pentose phosphate pathway. Transketolase and transaldolase reactions, however, enable R. japonicum to produce the precursors for purine and pyrimidine biosynthesis from fructose-6-phosphate and glyceraldehyde-3-phosphate. A constitutive nicotinamide adenine dinucleotide-linked 6-phosphogluconate dehydrogenase has been detected. The enzyme is stimulated by either mannitol or fuctose and might initiate a new catabolic pathway. R. japonicum isolate I-110, characterized by shorter generation times on glucose and greater nitrogen-fixing efficiency, oxidizes glucose more extensively than type L1-110 and utilizes preferentially the Embden-Meyerhof-Parnas pathway, whereas the Entner-Doudoroff pathway apparently predominates in type L1-110.
Detection and characterization of plasmids in Pseudomonas glycinea
Authors: Curiale M S , Mills D
Published: January 2020

Pathogenic strains of Pseudomonas glycinea were shown to possess plasmid deoxyribonucleic acid by dye-buoyant density gradient centrifugation. The size and number of plasmids of four different isolates were determined by neutral sucrose gradient centrifugation. Two isolates were found to harbor a single plasmid; however, they differed in size, having molecular weights of 43 X 10(6) and 54 X 10(6). Two other isolates each contained two different plasmids. Plasmids with molecular weights of 43 X 10(6) and 73 X 10(6) were observed in one isolate, and the other carried plasmids with molecular weights of 25 X 10(6) and 87 X 10(6). An auxotrophic mutant derived from the latter strain was found to contain plasmids of identical size. The plasmids were found to be under stringent control of replication, having plasmid copies of 1.0 to 2.7 per chromosome equivalent. By the dye-cesium chloride technique, the mutant showed twice as much covalently closed circular deoxyribonucleic acid as did the parental strain.
Phototaxis and membrane potential in the photosynthetic bacterium Rhodospirillum rubrum
Authors: Harayama S , Iino T
Published: January 2020

Cells of the photosynthetic bacterium Rhodospirillum rubrum cultivated anaerobically in light show phototaxis. The behavior of individual cells in response to the phenomenon is reversal(s) of the swimming direction when the intensity of the light available to them abruptly decreases. The tactic response was inhibited by antimycin, an inhibitor of the photosynthetic electron transfer system. The inhibitory effect of antimycin was overcome by phenazine methosulfate. Motility of the cells was not impaired by antimycin under aerobic conditions. Valinomycin plus potassium also inhibited their phototactic response; however, valinomycin or potassium alone had no effect. A change in membrane potential of the cells was measured as an absorbance change of carotenoid. Changes in the membrane potential caused by "on-off" light were prevented by antimycin and by valinomycin plus potassium, but not by antimycin plus phenazine methosulfate nor valinomycin or potassium alone. The results indicated that the phototactic response of R. rubrum is mediated by a sudden change in electron flow in the photosynthetic electron transfer system, and that the membrane potential plays an important role in manifestation of the response.
Fine-structure mapping and complementation analysis of the Escherichia coli cysB gene
Authors: Tully M , Yudkin M D
Published: January 2020

Sixty-two point mutations were isolated in Escherichia coli by means of transduction with mutagenized phage P1. Twenty-two deletions extending into cysB but able to recombine with at least some of the point mutations were isolated on a transmissible E. coli plasmid. Mapping of the point mutations against the deletions divided the former into 16 deletion groups. Nine merodiploids were constructed in which the chromosome carried one of the three point mutations most distal to the trp operon and in which a plasmid carried one of the three point mutations most proximal to the trp operon. All of these showed a Cys-phenotype. It follows that mutations at the two extreme ends of the region belong to the same complementation group.
Developmental-stage-dependent adenine transport in Neurospora crassa
Authors: Pendyala L , Wellman A M
Published: January 2020

Although germinated conidia of Neurospora crassa transport adenine through two different systems, only one of these, namely, the general purine transport system, which transports adenine, hypoxanthine, guanine, and 6-methylpurine, is present in freshly harvested conidia of the wild type. The second system develops during germination. The latter system can transport adenine and 6-methylpurine. Time course and kinetic studies of adenine transport in freshly harvested conidia of an ad-8 mutant indicated that, in contrast to the wild type, the general purine transport activity is very low in this strain and that the second adenine transport system is possibly present in the ungerminated conidia. A study of adenine and hypoxanthine uptake in ad-8 and ad-4 mutants, both of which cannot utilize hypoxanthine for growth, isolated that the two transport systems may be under different metabolic controls.
Influence of osmolarity of the growth medium on the outer membrane protein pattern of Escherichia coli
Authors: Alphen W V , Lugtenberg B
Published: January 2020

Supplementation of the growth medium with high concentrations of NaCl, KCl, or sucrose caused a drastic change in the ratio of the two peptidoglycan-associated major outer membrane proteins of Escherichia coli K-12 in that the amounts of proteins b and c present in cell envelope preparations decreased and increased, respectively. Kinetic studies showed that, after the osmolarity of the medium was changed, one protein was hardly incorporated into the membrane, whereas the other was incorporated with an increased rate. After about 1.5 to 2 generations, the cell envelopes obtained the b/c ratio characteristic for the new medium, and both proteins were subsequently incorporated in the cell ensured this new ratio. Once proteins b and c were incorporated in the cell envelope, they were not converted into each other by changes in osmolarity of the growth medium.
Release of periplasmic enzymes from Escherichia coli by penicillin-ethylenediaminetetraacetate treatment
Authors: Ananthaswamy H N
Published: January 2020

When Escherichia coli cells are converted into spheroplasts by penicillin treatment, none of the periplasmic enzymes is released. However, incubation of the penicillin-induced spheroplasts in a medium containing ethylenediaminetetraacetic acid caused the release of endonuclease I and cyclic phosphodiesterase but not of beta-galactosidase.
Isolation and Characterization of Specialized Lambda Transducing Bacteriophage Carrying the
metBJF
Methionine Gene Cluster
Authors: Johnson James R. , Greene Ronald C. , Krueger Judy Heilig
Published: January 2020

Secondary attachment site lysogens of Δ
att
λ
Δ
ppc-argECBH
strains of
Escherichia coli
with λ
c
I857 integrated into the
bfe
gene (88 min) were isolated. Of 20 such lysogens examined, 2 produce lysates with transducing phage containing the
metBJF
gene cluster (87 min). Reintroduction of the
ppc-argECBH
chromosome segment (which lies between the
bfe
and
met
genes) into these strains virtually abolishes the production of
met
transducing phage. All of the phage examined have lost essential genes from the left arm of the λ chromosome. Approximately 85% of the phage appear to have the same genetic composition, containing the
metBJF
gene cluster, but not the closely linked gene
cytR
, and having lost phage genes
G
and
J
. Analytical CsCl density gradient centrifugation of five representatives of this major class of phage shows four of them to have identical densities (lighter than λ), while the fifth cannot be resolved from λ. The four apparently identical phage were isolated from three separate lysates, which suggests the existence of preferred sites for illegitimate recombination on the bacterial and phage chromosomes. Three specialized transducing phage that carry
cytR
in addition to
metB, metJ
, and
metF
have also been studied. Each of these viruses has a different amount of phage deoxyribonucleic acid. Two of them have less deoxyribonucleic acid than λ, whereas the third has about the same amount. The
metB, metF
, and
cytR
genes of the transducing phage have been shown to function in vivo. The phage-borne
metB
and
metF
genes are subject to
metJ
-mediated repression.
Location and properties of glucose dehydrogenase in sporulating cells and spores of Bacillus subtilis
Authors: Fujita Y , Ramaley R , Freese E
Published: January 2020

Late during sporulation, Bacillus subtilis produces glucose dehydrogenase (GlcDH; EC 1.1.1.47), which can react with D-glucose or 2-deoxy-D-glucose and can use nicotinamide adenine dinucleotide (NAD) or nicotinamide adenine dinucleotide phosphate (NADP) as a cofactor. This enzyme is found mainly in the forespore compartment and is present in spores; it is probably made exclusively in the forespore. The properties of GlcDH were determined both in crude cell extracts and after purification. The enzyme is stable at pH 6.5 but labile at pH 8 or higher; the pH optimum of enzyme activity is 8. After inactivation at pH 8, the activity can be recovered in crude extracts, but not in solutions of the purified enzyme, by incubation with 3 M KCl and 5 mM NAD or NADP. As determined by gel filtration, enzymatically active GlcDH has a molecular weight of about 115,000 (if the enzyme is assumed to be globular). GlcDH is distinct from a catabolite-repressible inositol dehydrogenase (EC 1.1.1.18), which can also react with D-glucose, requires specifically NAD as a cofactor, and has an electrophoretic mobility different from that of GlcDH.
Effect of the relA gene on derepression of amino acid biosynthetic enzymes in growing Escherichia coli depends on the pathway being derepressed
Authors: Furano A V , Wittel F P
Published: January 2020

Derepression of an enzyme in the arginine biosynthetic pathway, but not of an enzyme in the tryptophan biosynthetic pathway, is inhibited during the stringent response produced by a partial deprivation of valyl transfer ribonucleic acid in a rel+ strain. In contrast, derepression of the tryptophan biosynthetic enzyme, but not of the arginine biosynthetic enzyme, was inhibited during the relaxed response produced in an isogenic relA strain by the partial deprivation of valyl transfer ribonucleic acid.
Motility of flagellated bacteria in viscous environments
Authors: Greenberg E P , Canale-Parola E
Published: January 2020

The lowest viscosity that immobilized flagellated bacteria such as Psedomonas aeruginosa, Spirillum serpens, and Escherichia coli was 60 centipoise (cp). Much higher viscosities (1,000 cp and higher) were required to immobilize two flagellated bacteria selectively isolated from nature by methods based on their ability to migrate through agar gels. The latter finding indicates that certain flagellated bacteria have the ability to swim through environments of relatively high viscosity. It is suggested that these flagellated bacteria possess a specialized type of motility apparatus suited to viscous conditions present in their habitats.
[3H] dihydrostreptomycin accumulation and binding to ribosomes in Rhizobium mutants with different levels of streptomycin resistance
Authors: Zelazna-Kowalska I
Published: January 2020

Rhizobium trifolii B1, a symbiotic nitrogen fixer, is sensitive to streptomycin (10 microgram/ml) and spontaneously produces spheroplast-like forms during cultivation. Streptomycin-resistant mutants selected with high doses of antibiotic (1,000 microgram/ml) showed pleiotropic changes, including loss of spheroplast formation and infectivity to plants, whereas mutants selected with low doses of streptomycin (10 to 100 microgram/ml) retained properties of parent strain B1 (I. Zelazna-Kowalska, Acta Microbiol. Pol., in press). The present studies revealed that strain B1 and its mutant with a high level of streptomycin resistance, B1 strH, accumulated the antibiotic at similar rates. Mutant B1 strL, with a low level of streptomycin resistance (up to 100 microgram/ml), accumulated the antibiotic at a lower rate. Ribosomes isolated from strains B1 and B2 strL bound [3H]dihydrostreptomycin, whereas those from strain B1 strH did not. These observations indicate that, in R. trifolii B1, mutation to a high level of streptomycin resistance affects ribosomal structure, whereas low-level resistance involves a change in membrane permeability.
Multivalent Induction of Biodegradative Threonine Deaminase
Authors: Yui Yoshiki , Watanabe Yasuyoshi , Ito Seiji , Shizuta Yutaka , Hayaishi Osamu
Published: January 2020

To determine the inducer(s) of the biodegradative threonine deaminase in
Escherichia coli
, the effects of various amino acids on the synthesis of this enzyme were investigated. The complex medium used hitherto for the enzyme induction can be completely replaced by a synthetic medium composed of 18 natural amino acids. In this synthetic medium, the omission of each of the seven amino acids threonine, serine, aspartic acid, methionine, valine, leucine, and arginine resulted in the greatest loss of enzyme formation. These seven amino acids did not significantly influence the uptake of other amino acids into the cells. Furthermore, they did not stimulate the conversion of inactive enzyme into an active form, since they did not affect the enzyme level in cells in which protein synthesis was inhibited by chloramphenicol. Threonine, serine, aspartic acid, and methionine failed to stimulate enzyme production in cells in which messenger ribonucleic acid synthesis was arrested by rifampin, whereas valine, leucine, and arginine stimulated enzyme synthesis under the same conditions. Therefore, the first four amino acids appear to act as inducers of the biodegradative threonine deaminase in
E. coli
and the last three amino acids appear to be amplifiers of enzyme production. The term “multivalent induction” has been proposed for this type of induction, i.e., enzyme induction only by the simultaneous presence of several amino acids.
Caulobacter flagellins
Authors: Lagenaur C , Agabian N
Published: January 2020

Flagellins from 17 Caulobacter strains were partially purified. Their molecular weights and immunological properties indicated that a two-component flagellin system is common among Caulobacters.
Formation of HfrH-type donor cells as a result of integrative suppression by R-F recombinant plasmids
Authors: Horodniceanu T , Dabernat H J , Lefevre J C , Bouanchaud D H
Published: January 2020

Three recombinant plasmids, resulting from recombination between an R plasmid of the FI incompatibility group and the F of HfrH, were introduced in a temperature-sensitive dnaA mutant to isolate Hfr-type-donors. All of the temperature-insensitive clones isolated from two of the three recombinant plasmids had the same origin and transfer pattern as the parental HfrH strain.
Phycocyanin synthesis and degradation in the blue-green bacterium Anacystis nidulans
Authors: Lau R H , MacKenzie M M , Doolittle W F
Published: January 2020

Cellular content and rates of synthesis of the apoprotein subunits of phycocyanin in Anacystis nidulans cultures undergoing, and recovering from, nitrate starvation were measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total and immunoprecipitable soluble proteins. Results indicated that (i) nitrate starvation provokes coordinate degradation of apoprotein subunits: (ii) de novo synthesis of these subunits is selectively depressed during starvation; (iii) nitrate restoration provokes coordinate increases in the rates of synthesis of these subunits, although maximal rates are not achieved for 6 to 10 h after readdition of nitrate; and (iv) illumination affects both relative and absolute rates of apoprotein formation.
In vitro synthesis of beta-galactosidase with ilv-lac fusion deoxyribonucleic acid as template
Authors: Wild J , Smith J M , Umbarger H E
Published: January 2020

An in vitro protein-synthesizing system has been developed to study the mechanism of induction of ilvC gene in Escherichia coli strain K-12. Deoxyribonucleic acid (DNA) from a lambda phage carrying an ilvC-lac fusion was employed as a template for the in vitro synthesis of beta-galactosidase under the control of the ilvC promoter. The use of this template allowed an investigation of the components required for induction of the ilvC gene and the kinetics of the induction. The in vitro synthesis of beta-galactosidase under the control of the ilvC promoter was found to be DNA, acetohydroxy acid, and guanosine-3'-diphosphate-5'-diphosphate dependent, and sensitive to rifampin, actinomycin D, and chloramphenicol. Uncoupling experiments indicate that the inducer, acetohydroxybutyrate, acts at the transcriptional level. Investigation of a proposed noninducible ilvC regulatory mutant has shown normal induction in vitro. It was also observed that an intact ilvA gene is not required for the induction of the ilvC gene.
Early stages of arthrospore maturation in Streptomyces
Authors: Manzanal M B , Hardisson C
Published: January 2020

In the sporogenesis of Streptomyces, two basic stages can be considered: sporulation septum synthesis and arthrospore maturation. Most of the information about the ultrastructural changes accompanying the sporogenesis refer to the first stage of the process, but nothing has been published about the evolution of the sporulation septum during maturation. In a previous paper, proposed three basic types of sporulation septum formation in Streptomyces. Our ultrastructural study on the evolution of the sporulation septum during the early stages of arthrospore maturation in seven species of Streptomyces indicates correlation between the sporulation septum type and its evolution during the arthrospore maturation. In types I and II the material of the annuli was incorporated into the lateral walls of the arthrospore, whereas in types II and III the deposits were lysed during the maturation. Only in type III was the arthrospore wall synthesized de novo. In type I there was total integration and in type II there was partial integration of the septum into the arthrospore wall.
ATP hydrolysis in a marine bacterium
Authors: Calcott P H , Bhatti A R
Published: January 2020

The membrane-bound adenosine triphosphatase of marine pseudomonad B-16, when solubilized, is able to rebind to depleted membrane residues of the bacterium and to those of Escherichia coli.
Expression of Escherichia coli fol alleles in Salmonella typhimurium
Authors: Goff C G , Sheldon R
Published: January 2020

Studies of the expression of Escherichia coli fol alleles in Salmonella typhimurium indicated that fol regulatory functions are highly conserved between these bacterial species.
Multiple forms of glucokinase from Dictyostelium discoideum
Authors: Killick K A , Wright B E
Published: January 2020

A single form of glucokinase with an apparent Km value equal to 0.12 mM glucose was detectable in extracts prepared from aggregating cells, whereas kinetic and electrophoretic evidence indicated the presence of this form as well as a second glucose-phosphorylating enzyme with a Km value of about 0.01 mM glucose in extracts from culminating cells.
Plasmid conferring increased sensitivity to mercuric chloride and cobalt chloride found in some laboratory strains of Escherichia coli K-12
Authors: Wang P Y , Relf J , Palchaudhuri S , Iyer V N
Published: January 2020

Some lines of the widely used strain CR34 of Escherichia coli K-12 carry a plasmid. The plasmid has a mass of 12 +/- 2 X 10(6) megadaltons and is maintained at a low copy number per cell (1 to 2), and this number is not amplified by growth of cells in the presence of chloramphenicol. The plasmid is designated as pCU3. The presence of pCU3 confers on the strain increased sensitivity to mercuric chloride and cobalt chloride. The plasmid has also been observed to fuse or recombine with the plasmid R64-11.
Effects of high temperature on Escherichia coli F pili
Authors: Novotny C P , Fives-Taylor P
Published: January 2020

The effects of high temperatures (46 to 50 degrees C) on the production of F pili by Escherichia coli were studied by electron microscopy. Attached F pili rapidly disappeared at 48 and 50 degrees C but not at 46 degrees C. Free pili were not denatured at these temperatures. The pili that disappeared from the cells at 50 degrees C did not appear as free pili in the culture supernatant fluid, indicating that the pili had retracted to the cell surface or into the cell. The adsorption of either R17 phage or F pili antibody to the sides of pili prevented retraction. The disappearance of pili was accompanied by a loss in the ability to adsorb R17 phage but not M13 phage, suggesting that the tip of a pilus remains exposed after retraction.
2-deoxygalactose, a specific substrate of the Salmonella typhiimurium galactose permease: its use for the isolation of galP mutants
Authors: Nagelkerke F , Postma P W
Published: January 2020

2-Deoxygalactose is a specific substrate of the galactose permease. The apparent Km is about 500 micron, compared to 45 micron for galactose, whereas the maximal rate of uptake is one-half to one-third of that of galactose. None of the other galactose transport systems, including methyl beta-D-thiogalactosides I and II, the beta-methyl-galactoside permease, and both arabinose systems, is able to catalyze transport of 2-deoxygalactose to a significant extent. 2-Deoxygalactose can also be used to isolate mutants defective in galactose permease, since it is bacteriostatic. Colonies that grow with lactate, malate, or succinate as a carbon source in the presence of 0.5 to 2 mM 2-doexygalactose were found to be mostly galP mutants, lacking galactose permease. Spontaneous 2-deoxygalactose-resistant strains arose with a frequency of about 2 X 10(-6). galP mutants have also been derived from pts deletion mutants that require galactose permease for growth on glucose. Revertants have been obtained that have acquired the parental phenotype.
Induction and Repression of Nitrate Reductase in
Neurospora crassa
Authors: Dantzig Anne H. , Zurowski Wayne K. , Ball Thomas M. , Nason Alvin
Published: January 2020

Synthesis of wild-type
Neurospora crassa
assimilatory nitrate reductase is induced in the presence of nitrate ions and repressed in the presence of ammonium ions. Effects of several
Neurospora
mutations on the regulation of this enzyme are shown: (i) the mutants,
nit-1
and
nit-3
, involving separate lesions, lack reduced nicotinamide adenine dinucleotide (NADPH)-nitrate reductase activity and at least one of three other activities associated with the wild-type enzyme. The two mutants do not require the presence of nitrate for induction of their aberrant nitrate reductases and are constitutive for their component nitrate reductase activities in the absence of ammonium ions. (ii) An analog of the wild-type enzyme (similar to the
nit-1
enzyme) is formed when wild type is grown in a medium in which molybdenum has been replaced by vanadium or tungsten; the resulting enzyme lacks NADPH-nitrate reductase activity. Unlike
nit-1
, wild type produced this analog only in the presence of nitrate. Contaminating nitrate does not appear to be responsible for the observed mutants' activities. Nitrate reductase is proposed to be autoregulated. (iii) Mutants (
am
) lacking NADPH-dependent glutamate dehydrogenase activity partially escape ammonium repression of nitrate reductase. The presence of nitrate is required for the enzyme's induction. (iv) A double mutant,
nit-1 am-2
, proved to be an ideal test system to study the repressive effects of nitrogen-containing metabolites on the induction of nitrate reductase activity. The double mutant does not require nitrate for induction of nitrate reductase, and synthesis of the enzyme is not repressed by the presence of high concentrations of ammonium ions. It is, however, repressed by the presence of any one of six amino acids. Nitrogen metabolites (other than ammonium) appear to be responsible for the mediation of “ammonium repression.”
Utilization of Oxalacetate by
Acinetobacter calcoaceticus
: Evidence for Coupling Between Malic Enzyme and Malic Dehydrogenase
Authors: Dolin M. I. , Juni E.
Published: January 2020

Growth of
Acinetobacter calcoaceticus
strain BD413 in malate-mineral medium resulted in the excretion of large quantities of oxalacetate. Malate was virtually depleted by the time the cell density reached 60% of its final value; most of the remaining growth took place at the expense of oxalacetate. Experiments in which oxalacetate was used as the initial substrate showed that pyruvate was not utilized until most of the oxalacetate disappeared. The generation time for growth on malate or oxalacetate was ∼40 min; the generation time for growth on pyruvate was 62 min, which implies that pyruvate transport may be rate limiting. Oxalacetate and pyruvate, however, supported approximately the same growth yield. These observations suggested that the first step in the utilization of oxalacetate as an energy source consisted of an enzymatic decarboxylation of the keto acid to pyruvate and CO
2
. Three enzyme reactions that carry out this decarboxylation have been detected in extracts of
A. calcoaceticus
. The first, which functioned maximally at pH 4.8, was attributable to the oxalacetate decarboxylase activity of oxidized diphosphopyridine nucleotide-malic enzyme. The second and third, which functioned in the neutral pH range, resulted from coupling of oxidized diphosphopyridine nucleotide-malic enzyme to reduced diphosphopyridine nucleotide-dependent malic dehydrogenase, and oxidized triphosphopyridine nucleotide-malic enzyme to a reduced triphosphopyridine nucleotide-dependent malic dehydrogenase. The efficiency of these coupled reactions was high enough so that the overall reaction could be physiologically significant.
Regulation of isopropylmalate isomerase synthesis in Neurospora crassa
Authors: Reichenbecher V E , Fischer M , Gross S R
Published: January 2020

The capacity to synthetize isopropylmalate isomerase (EC 4.2.1.33) by Neurospora crassa increased during induction in the presence of cycloheximide but was inhibited by proflavine and other inhibitors of RNA synthesis. Turnover of the enzyme once formed appeared negligible, but the message (measured as enzyme-forming capacity) had a half-life of 4 to 8 min. A comparison of the kinetics of induction in the wild type and a newly isolated alpha-isopropylmalate-permeable strain suggested strongly that feedback control by leucine of alpha-isopropylmalate production can adequately serve as the primary physiological regulator of endogenous inducer concentration. Genetic data are presented which implicate the involvement of two unlinked genes, ipm-1 and ipm-2, in determining permeation of alpha-isopropylmalate.
Cellular autolytic activity in synchronized populations of Streptococcus faecium
Authors: Hinks R P , Daneo-Moore L , Shockman G D
Published: January 2020

The autolytic capacity of Streptococcus faecium (S. faecalis ATCC 9790) varied during synchronous cell division. This phenomenon was initially observed in rapidly dividing populations (TD=30 to 33 min) synchronized by a combination of induction and size selection techniques. To minimize the problems inherent in studies of cells containing overlapping chromosome cycles and possible artifacts generated by induction techniques, the autolytic capacities of slowly dividing populations (TD=60 to 110 min) synchronized by selection only were examined. Although the overall level of cellular autolytic capacity was observed to decline with decreasing growth rate, sharp, periodic fluctuations in cellular autolytic capacity were seen during synchronous growth at all growth rates examined. On the basis of similar patterns of cyclic fluctuations in autolytic capacity of cultures synchronized by (i) selection, (ii) amino acid starvation followed by size selection, and (iii) amino acid starvation followed by inhibition of DNA synthesis, a link of such fluctuations with the cell division cycle has been postulated.
Occurrence of glutathione in bacteria
Authors: Fahey R C , Brown W C , Adams W B , Worsham M B
Published: January 2020

Glutathione and soluble thiol content were examined in a broad spectrum of bacteria. Significant soluble thiol was present in all cases. The thiol compound was glutathione in most of the gram-negative bacteria but not in most of the gram-positive bacteria studied. Glutathione was absent in four anerobes and one microaerophile but was present in a blue-green bacterium. The glutathione content of Escherichia coli increased significantly during transition from exponential to stationary phase.
Osmotic Effects on Membrane Permeability in a Marine Bacterium
Authors: MacLeod Robert A. , Goodbody Margaret , Thompson John
Published: January 2020

When cells of
Alteromonas haloplanktis
214 (ATCC 19855) were preloaded with α-[
14
C]aminoisobutyric acid or the K
+
in the cells was labeled with
42
K by incubation in a buffered salt solution containing 0.05 M MgSO
4
, 0.01 M KCl, and 0.3 M NaCl, the cells retained their radioactivity when resuspended in the same salt solution. When NaCl was omitted from the solution, 80 to 90% of the radioactivity was lost from the cells. Cells suspended at intermediate concentrations of NaCl also lost radioactivity. New steady-state levels of the intracellular solutes were established within 15 s of suspending the cells; the percentage of radioactivity retained at each level decreased proportionately as the osmolality of the NaCl in the suspending solution decreased. With minor variations in effectiveness, MgCl
2
, LiCl, and sucrose could substitute for NaCl on an equiosmolal basis for the retention of radioactivity by the cells. KCl, RbCl, and CsCl were appreciably less effective as replacements for NaCl, particularly when their osmolalities in the suspending solutions were low. The amount of α-[
14
C]aminoisobutyric acid taken up by the cells at the steady-state level increased to a maximum as the NaCl concentration in the suspending medium increased to 0.3 M. At suboptimal levels of NaCl, either LiCl or sucrose could substitute for NaCl in increasing the steady-state levels. The results obtained indicate that the porosity of the cytoplasmic membrane of this organism is determined by the difference between the osmotic pressure of the cytoplasm and the suspending medium. The lesser effectiveness of K
+
, Rb
+
, and Cs
+
than Na
+
, Li, or Mg
2+
in permitting the retention of solutes by the cells is attributed to the greater penetrability of the hydrated ions of the former group through the dilated pores of a stretched cytoplasmic membrane.
Increased antimetabolite sensitivity with variation of carbon source during growth
Authors: Jensen R A , Calhoun D H
Published: January 2020

In Serratia marcescens, analogs of leucine (norleucine), methionine (alpha-methylmethionine), histidine (3-amino-1,2,4-triazolealanine), tyrosine (p-aminophenylalanine), and tryptophan (7-methylindole) are conditional inhibitors of growth; inhibition occurs during the metabolism of some carbon sources but not with others. A further increase in sensitivity to growth inhibition by these analogs can be accomplished through the use of particular combinations of carbon sources present in the inoculum and in the subsequent analog-containing culture medium. Variable sensitivity to analog-mediated inhibition of growth observed during growth on glucose, glycerol, fructose, or citrate correlated inversely with the intracellular pool sizes of the amino acids cognate to the analogs used. The above-cited results, in conjunction with previous results obtained with Pseudomonas aeruginosa and Bacillus subtilis, involve diverse biochemical pathways and suggest that nutritional manipulation to alter the pattern of carbon flow in microorganisms is a generally useful means to accomplish increased sensitivity to growth inhibition by metabolite analogs.
Interspecies transformation in Bacillus: mechanism of heterologous intergenote transformation
Authors: Harris-Warrick R M , Lederberg J
Published: January 2020

Bacillus subtilis-Bacillus globigii hybrids were made by integration of the B. globigii aromatic region (aroB to aroE) as an intergenote in the B. subtillis chromosome. Transformation of the heterologous intergenote by B. subtillis DNA (or vice versa) occurred at about 10% of the frequency of homologous transformation by hybrid donors into the same region. Heterologous intergenote crosses were unusually sensitive to shear fragmentations of donor DNA to sizes less than 30 X 10(6) to 40 X 10(6) daltons. In all cases, the entire intergenote was transferred en bloc. Homologous transformation of intergenote markers by B. globigii DNA was not unusually shear sensitive, and linkage was normal for markers in the intergenote. A model is proposed in which efficient heterologous intergenote transformation occurs by recognition and base pairing of homologous DNA sequences of both flanks of the intergenote.
Replication of plasmid DNA in Proteus mirabilis in limiting concentrations of thymine
Authors: Womble D D , Warren R L , Rownd R H
Published: January 2020

Replicating forms of the R plasmid pRR12 and the colicin E1 plasmid RSF2124 were isolated from Proteus mirabilis after growth in medium containing a limiting concentration of thymine. Both plasmids were replicated as partially supercoiled intermediates, which have densities between the values of covalently closed circular and nicked circular plasmid DNA in ethidium bromide-cesium chloride gradients. In addition, both plasmids had replication intermediates, which have densities lower than that of linear P. mirabilis chromosomal DNA. Some structural features of these replication intermediates were examined.
Pathways of assimilation of [13N]N2 and 13NH4+ by cyanobacteria with and without heterocysts
Authors: Meeks J C , Wolk C P , Lockau W , Schilling N , Shaffer P W , Chien W S
Published: January 2020

The principal initial product of metabolism of [13N]N2 and 13NH4+ by five diverse cyanobacteria is glutamine. Methionine sulfoximine inhibits formation of [13N]glutamine except in the case of Gloeothece sp., an organism with a thick sheath through which the inhibitor may not penetrate. Thus, glutamine synthetase appears to catalyze the initial step in the assimilation of N2-derived or exogenous NH4+ by these organisms. [13N]Glutamate is, in all cases, the second major product of assimilation of 13N-labeled N2 and NH4+. In all of the N2-fixing cyanobacteria studied, the fraction of 13N in glutamine declines and that in glutamate increases with increasing times of assimilation of [13N]N2 and 13NH4+, and (Gloeothece again excepted) methionine sulfoximine reduces incorporation of 13N into glutamate as well as into glutamine. Glutamate synthase therefore appears to catalyze the formation of glutamate in a wide range of N2-fixing cyanobacteria. However, the major fraction of [13N]glutamate formed by Anacystis nidulans incubated with 13NH4+ may be formed by glutamic acid dehydrogenase. The formation of [13N]alanine from 13NH4+ appears to be catalyzed principally either by alanine dehydrogenase (as in Cylindrospermum licheniforme) or by a transaminase (as in Anabaena variabilis).
Purification and characterization of a hyaluronidase associated with a temperate bacteriophage of group A, type 49 streptococci
Authors: Benchetrit L C , Gray E D , Edstrom R D , Wannamaker L W
Published: January 2020

Urea treatment of a temperate bacteriophage from a type 49 strain of group A streptococcus (Streptococcus pyogenes) followed by ammonium sulfate fractionation, ion exchange, and affinity chromatography of solubilized proteins provided for the recovery (12%) and purification (44-fold) of the phage-associated hyaluronidase. The molecular weight of the homogeneous, purified enzyme was estimated to be 71,000 by polyacrylamide gel electrophoresis (in the presence of sodium dodecyl sulfate) and 75,000 by gel filtration with Sephacryl S-200. The enzyme has a pH optimum of 5.5, a Vmax of 0.1 absorbance unit/min per microgram of protein, and a Km of 4.8 X 10(-2) mg/ml with umbilical cord hyaluronic acid as substrate. Of the cations tested, calcium and magnesium were the only effectors of the enzyme. The enzyme is a glycoprotein (7.25% carbohydrate) containing glucose, galactose, and glucosamine. Analysis of the amino acid composition revealed a predominance of acidic amino acids and a relatively high content of cysteine. The partial specific volume, estimated from the amino acid and sugar analyses, was 0.725 cm3/g.
Multiplicity of genome equivalents in the radiation-resistant bacterium Micrococcus radiodurans
Authors: Hansen M T
Published: January 2020

The complexity of the genome of Micrococcus radiodurans was determined to be (2.0 +/- 0.3) X 10(9) daltons by DNA renaturation kinetics. The number of genome equivalents of DNA per cell was calculated from the complexity and the content of DNA. A lower limit of four genome equivalents per cell was approached with decreasing growth rate. Thus, no haploid stage appeared to be realized in this organism. The replication time was estimated from the kinetics and amount of residual DNA synthesis after inhibiting initiation of new rounds of replication. From this, the redundancy of terminal genetic markers was calculated to vary with growth rate from four to approximately eight copies per cell. All genetic material, including the least abundant, is thus multiply represented in each cell. The potential significance of the maintenance in each cell of multiple gene copies is discussed in relation to the extreme radiation resistance of M. radiodurans.
Salmonella typhimurium peptidase active on carnosine
Authors: Kirsh M , Dembinski D R , Hartman P E , Miller C G
Published: January 2020

Wild-type Salmonella typhimurium can use carnosine (beta-alanyl-L-histidine) as a source of histidine, but carnosine utilization is blocked in particular mutants defective in the constitutive enzyme peptidase D, the product of the pepD gene. Biochemical evidence for assigning carnosinase activity to peptidase D (a broad-specificity dipeptidase) includes: (i) coelution of carnosinase and dipeptidase activity from diethylaminoethyl-cellulose and Bio-Gel P-300 columns; (ii) coelectrophoresis of carnosinase and dipeptidase on polyacrylamide gels; and (iii) inactivation of carnosinase and dipeptidase activities at identical rates at both 4 and 42 degrees C. Genetic evidence indicates that mutations leading to loss of carnosinase activity map at pepD. Several independent pepD mutants have been isolated by different selection procedures, and the patterns of peptide utilization of strains carrying various pepD alleles have been studied. Many pepD mutations lead to the production of partially active peptidase D enzymes with substrate specificities that differ strikingly from those of the wild-type enzyme. The growth yields of carnosinase-deficient strains growing in Difco nutrient broth indicate that carnosine is the major utilizable source of histidine in this medium.
Evidence linking penicillinase formation and secretion to lipid metabolism in Bacillus licheniformis
Authors: Fishman Y , Rottem S , Citri N
Published: January 2020

The formation of penicillinase by cultures of Bacillus licheniformis was preferentially suppressed by cerulenin, an antibiotic known to specifically inhibit fatty acid synthesis in microorganisms. The effect was studied at cerulenin concentrations that had almost no effect on the rate of cell growth and overall protein synthesis, but that reduced the rate of [14C]acetate incorporation (by 50 to 70%), indicating partial inhibition of lipid synthesis. The levels of both the released enzyme (exopenicillinase) and its cell-bound precursor were reduced to the same extent (70% to 80%). Enzyme formation was gradually resumed after the removal of cerulenin or the addition of a mixture of fatty acids prepared from lipids extracted from B. licheniformis. Reversal was less effective as the time interval between treatment with cerulenin and addition of fatty acids increased. We conclude that de novo synthesis of fatty acids is required for the formation of both the membrane-bound and extracellular penicillinase. Suppression of the membrane-bound enzyme is a likely consequence of the altered membrane (decreased lipid-to-lipid ratio and increased density) seen in cerulenin-treated preparations. The corresponding suppression of exopenicillinase is consistent with the view that it is derived from the membrane-bound form. A mechanism linking the general class of exportable proteins to specific aspects of lipid synthesis is discussed.
Protease activity during cell differentiation of the cellular slime mold Dictyostelium discoideum
Authors: Fong D , Rutherford C L
Published: January 2020

Individual aggregates, migrating pseudoplasmodia, and sorocarps of Dictyostelium discoideum were assayed for proteolytic activities by colorimetric and fluorometric techniques. Cathepsin D-like and cathepsin B-like acid protease activities were found to decrease throughout development, but the patterns of decrease were different for the two enzymes. A gradual decrease was found for cathepsin D, whereas a sharp decrease between aggregates and migrating pseudoplasmodia was detected for cathepsin B. By using microdissection techniques and fluorometric assays for amino acids and peptides, prestalk cells and prespore cells exhibited no difference in cathepsin D activity, whereas cathepsin B activity was higher in the prestalk cells. Similarly, stalk cells and spores in the sorocarps showed no difference in cathepsin D activity, but showed a fivefold higher cathepsin B activity in the stalk cells. This finding suggests a possible role for cathepsin B in stalk cell differentiation.
Reduction of ferric iron by L-lactate and DL-glycerol-3-phosphate in membrane preparations from Staphylococcus aureus and interactions with the nitrate reductase system
Authors: Lascelles J , Burke K A
Published: January 2020

Membrane fractions with L-lactate dehydrogenase, sn-glycerol-3-phosphate (G3P) dehydrogenase, and nitrate reductase activities were prepared from Staphylococcus aureus wild-type and hem mutant strains. These preparations reduced ferric to ferrous iron with L-lactate or G3P as the source of reductant, using ferrozine to trap the ferrous iron. Reduction of ferric iron was insensitive to 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) with either L-lactate or G3P as reductant, but oxalate and dicumarol inhibited reduction with L-lactate as substrate. The membranes had L-lactate- and G3P-nitrate reductase activities, which were inhibited by azide and by HQNO. Reduction of ferric iron under anaerobic conditions was inhibited by nitrate with preparations from the wild-type strain. This effect of nitrate was abolished by blocking electron transport to the nitrate reductase system with azide or HQNO. Nitrate did not inhibit reduction of ferric iron in heme-depleted membranes from the hem mutant unless hemin was added to restore L-lactate- and G3P-nitrate reductase activity. We conclude that reduced components of the electron transport chain that precede cytochrome b serve as the source of reductant for ferric iron and that these components are oxidized preferentially by a functional nitrate reductase system.