bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of the synthesis of ribonucleoside diphosphate reductase in Escherichia coli: specific activity of the enzyme in relationship to perturbations of DNA replication
Authors: Filpula D , Fuchs J A
Published: January 2020

Ribonucleoside diphosphate reductase (RDP reductase) activity was found to greatly increase after a shift to the nonpermissive temperature in Escherichia coli mutants temperature sensitive for DNA elongation (dnaE dnaG dnaZ lig) or DNA initiation (dnaA dnaC dnaI). However, the kinetics of increase in RDP reductase after a shift to nonpermissive conditions were significantly different in initiation-defective mutants compared with elongation-defective mutants. In strains without defects in DNA metabolism, the specific activity of RDP reductase was found to increase with increasing growth rate. Nutritional shifts to faster growth conditions caused cells to transiently overproduce RDP reductase before adjusting to the new steady-state conditions.
Diameter of cells of a thermosensitive dnaA mutant of Escherichia coli cultivated at intermediate temperatures
Authors: Pritchard R H , Meacock P A , Orr E
Published: January 2020

Strains of Escherichia coli K-12 carrying the dnaA46 mutation exhibited a progressively decreasing DNA concentration and a progressively increasing cell size as the temperature was raised from 31 to 37 degrees C. Above 37 degrees C, steady-state exponential growth could not be maintained. The increase in average cell size with increasing growth temperature was due to an increase in cell length. There was no change in cell width. This seems to rule out the hypothesis that the increase in cell width in thy strains cultivated on low concentrations of thymine is due to the decrease in DNA concentration which also occurs under these conditions.
Isolation and characterization of morphogenetic mutants of Arthrobacter crystallopoietes
Authors: Achberger E C , Kolenbrander P E
Published: January 2020

Mutants of Arthrobacter crystallopoietes that exhibited altered ability to undergo the normal sphere-to-rod-to-sphere morphogenetic cycle were isolated. The procedure used to isolate these mutants involved velocity sedimentation in a sterile sucrose gradient to separate morphogenesis-deficient spherical cells from rod-shaped cells capable of normal morphogenesis. Three classes of mutants were obtained: (i) those that cannot form rods, (ii) those that cannot form long rods, and (iii) those that form long rods but exhibit more extensive rudimentary branching than the wild type. The isolation and characterization of these mutants are described, and the use of these mutants in the study of the morphogenetic cycle of arthrobacters is discussed.
Location of ribosome-binding sites on the tetracycline resistance transposon Tn10
Authors: Calame K , Nakada D , Ihler G
Published: January 2020

Eight ribosome-binding sites were located on the single-stranded Tn10 DNA loop which was formed after denaturation of lambda phage DNA containing the Tn10 transposon sequence. Ribosomes were bound only to the Tn10 loop contained on the R strand of lambda DNA but not to that on the L strand, suggesting that one of the two strands of Tn10 DNA is selectively transcribed. Six of the eight ribosome binding sites were located in one-half of the DNA loop. The maximum sizes of potential polypeptides were calculated for these genes to range between 9,500 and 84,000 daltons.
Coenzyme B12-dependent diol dehydratase: regulation of apoenzyme synthesis in Klebsiella pneumoniae (Aerobacter aerogenes) ATCC 8724
Authors: Toraya T , Honda S , Kuno S , Fukui S
Published: January 2020

Immunochemical studies demonstrated that Klebsiella pneumoniae (Aerobacter aerogenes) ATCC 8724 produces only a single diol dehydratase whether grown on glycerol or on 1,2-propanediol. The enzyme was subject to induction by 1,2-diols and to catabolite repression reversed by cyclic AMP.
Bacillus subtilis spore coats: complexity and purification of a unique polypeptide component
Authors: Goldman R C , Tipper D J
Published: January 2020

Extensively washed, dormant spores of Bacillus subtilis were disrupted with glass beads in buffer at pH 7 in the presence of protease inhibitors. Approximately 31% of the total spore protein was soluble, and another 14% was removed from the insoluble fraction by hydrolysis with lysozyme and washing with 1 M KCl and 0.1% sodium dodecyl sulfate. The residual spore integuments comprised 55% of the total spore proteins and consisted of coats and residual membrane components. Treatment of integuments with sodium dodecyl sulfate and reducing agents at pH 10 solubilized 40% of the total spore protein. Seven low-molecular-weight polypeptide components of this solubilized fraction comprised 27% of the total spore protein. They are not normal membrane components and reassociated to form fibrillar structures resembling spore coat fragments. The residual insoluble material (15% of the total spore protein) was rich in cysteine and was probably also derived from the spore coats. A solubilized coat polypeptide of molecular weight 12,200 has been purified in good yield (4 to 5% of the total spore protein). Five amino acids account for 92% of its total amino acid residues: glycine, 19%; tyrosine, 31%; proline, 23%; arginine, 13%; and phenylalanine, 6%.
Genetic and biochemical characterization of kirromycin resistance mutations in Bacillus subtilis
Authors: Smith I , Paress P
Published: January 2020

Spontaneous mutations causing resistance to the EF-Tu-specific antibiotic kirromycin have been isolated and mapped in Bacillus subtilis. Three-factor transductional and transformational crosses have placed the kir locus proximal to ery-1 and distal to strA (rpsL) and several mutations affecting elongation factors EF-G and EF-Tu, in the order: cysA strA [fus-1/ts-6(EF-G)] [ts-5(EF-Tu)] kir ery-1 spcA. Purified EF-Tu from mutant strains is more resistant to kirromycin as measured by in vitro protein synthesis and also shows a more acidic isoelectric point than wild-type EF-Tu. This indicates that the kir locus is the genetic determinant (tuf) for EF-Tu and that there is a single active gene for this enzyme in B. subtilis.
Comparative study of DNA methylation in three unicellular eucaryotes
Authors: Hattman S , Kenny C , Berger L , Pratt K
Published: January 2020

We have analyzed the nature/content of methylated bases in the nuclear DNA of three unicellular eucaryotes. The pattern of methylation was different for each of the three organisms studied: Saccharomyces cerevisiae contained only 5-methylcytosine; Tetrahymena pyriformis contained only N6-methyladenine; and Chlamydomonas reinhardi contained both modified bases.
Effect of growth temperature on membrane fatty acid composition and susceptibility to cold shock of Bacillus amyloliquefaciens
Authors: Paton J C , McMurchie E J , May B K , Elliott W H
Published: January 2020

We investigated the fatty acid composition of the membrane of Bacillus amyloliquefaciens grown at different temperatures. A decrease in growth temperature was accompanied by an increase in the ratio of branched- to straight-chain fatty acids and a marked increase in the level of unsaturation of branched-chain fatty acids. When cells of this organism grown at 30 degrees C were cold shocked, viability and ability to secrete extracellular protease were lost. Growth of this organism at lower temperatures or addition of Tween 80 to cells caused the critical temperature zone for cold shocking to be lowered significantly. These results suggest a direct correlation between membrane fluidity and the susceptibility to cold shock.
Stimulation of tetrapyrrole formation in Rhizobium japonicum by restricted aeration
Authors: Avissar Y J , Nadler K D
Published: January 2020

Cultures of Rhizobium japonicum were grown with vigorous aeration to stationary phase and were then incubated under restricted aeration for several days. Under these "microaerobic" conditions, cellular heme content increased 10-fold, and visible amounts of porphyrins were released into the culture medium. The two predominant porphyrins produced were identified, on the basis of their spectrophotometric and chromatographic properties, as protoporphyrin and coproporphyrin. The cytochrome complement of microaerobic cells partially resembled that of the symbiotic bacteria in that cytochromes alpha-alpha3 were absent and a CO-binding cytochrome 552 was present. During the period of restricted aeration, at the time that the heme content was increasing, there was a similar 10-fold increase in the activities of the first two enzymes of heme biosynthesis, delta-aminolevulinic acid synthase and delta-aminolevulinic acid dehydrase. However, during the same period, the activity of succinyl thiokinase (an enzyme that is required in large amounts whether or not heme is being produced) increased only twofold. These results suggest that reduced oxygen tension may play a role in inducing heme synthesis necessary for leghemoglobin formation and bacterial differentiation in soybean root nodules.
Mycoplasma growth factors in bovine serum fraction
Authors: Washburn L R , Hughes J H , Somerson N L
Published: January 2020

Mycoplasma growth factors in bovine serum fraction were separated by Sephadex G150 column chromatography and density ultracentrifugation. The major growth factor of bovine serum fraction eluted from the Sephadex column in the void volume. Its growth-supporting activity was greatly enhanced by the presence of bovine serum albumin in the mycoplasma culture media. Other investigators had previously identified the major growth factor in serum as an alpha-lipoprotein. Although density ultracentrifugation revealed the presence of traces of a high-density lipoprotein in bovine serum fraction, another, less dense component, isolated by ultracentrifugation (component 3) and containing cholesterol, cholesteryl esters, free fatty acids, triglycerides, and protein, but no lipoprotein, exhibited considerably more growth-supporting activity than did the high-density lipoprotein, thus indicating that at least two mycoplasma species do not require intact serum lipoprotein for growth. Both the high-density lipoprotein and component 3 exhibited maximum activity only in the presence of bovine serum albumin. A chloroform extract containing component 3 lipids combined with bovine serum albumin to form an effective, partially defined, less complex substitute for serum in mycoplasma culture media.
Control of biodegradative threonine dehydratase inducibility by cyclic AMP in energy-restricted Escherichia coli
Authors: Phillips A T , Egan R M , Lewis B
Published: January 2020

To explain the requirement for anaerobic conditions in the induction of biodegradative L-threonine dehydratase in Escherichia coli, Crookes strain, measurements of cyclic AMP (cAMP) were made during aerobic and anaerobic growth and upon an aerobic-to-anaerobic transition. Internal cAMP levels were similar (5 to 10 muM) throughout exponential growth, whether aerobic or anaerobic, but only during anaerobiosis was threonine dehydratase synthesized. When an exponentially growing aerobic culture was made anaerobic, a sharp increase in internal cAMP was noted, reaching 300 muM within 10 min and declining thereafter to normal anaerobic levels. Threonine dehydratase synthesis was detected immediately after the attainment of peak cAMP levels and continued for several generations. A similar pattern but with less accumulation of cAMP and less threonine dehydratase production was also noted upon treatment of an aerobically growing culture with KCN. Pyruvate addition at the time of anaerobic shock severely affected both cAMP accumulation and threonine dehydratase synthesis; however, externally added cAMP could partially counter the pyruvate effect on enzyme synthesis. The conclusion was reached that conditions which resulted in a temporary energy deficit brought about the major accumulation of cAMP, and this elevated level served as a signal for initiation of threonine dehydratase synthesis to supply energy by the nonoxidative degradation of threonine.
Correlation of enzymatic activity and thermal resistance with hydration state in ungerminated Neurospora conidia
Authors: Fahey R C , Mikolajczyk S D , Brody S
Published: January 2020

Ungerminated Neurospora crassa conidia were incubated at 0, 50, and 100% relative humidity, giving rise to conidia in dry, quasi-dry, and wet hydration states, respectively. Metabolic activity was detected by monitoring levels of reduced glutathione (GSH), oxidized glutathione (GSSG), and the soluble-amino acid pools as a function of incubation time. Wet conidia (approximately 65% water content) exhibited significant metabolic activity as evidenced by: (i) reduction of GSSG to GSH, (ii) degradation of GSH, and (iii) changes in the pool sizes of certain amino acids. GSSG accumulated slowly in dry conidia (less than 5% water content) and more rapidly in quasi-dry conidia (approximately 13% water content), indicating that enzymatic reduction of GSSG is inactive in these states. Longevity and thermal resistance were high for dry conidia and low for wet conidia, but were not influenced by variation in GSSG content. The water content of conidia exhibited a hysteresis effect in that at a given relative humidity previously dried conidia attained a lower water content than freshly harvested conidia.
Dark hexose metabolism by photoautotrophically and heterotrophically grown cells of the blue-green alga (Cyanobacterium) Nostoc sp. strain Mac
Authors: Bottomley P J , van Baalen C
Published: January 2020

Photoautotrophically grown cells of the blue-green alga (cyanobacterium) Nostoc sp. strain Mac assimilated and oxidized both glucose and fructose in the dark at different rates. The rate of fructose metabolism in these cells could be stimulated by casein hydrolysate, the effect being most pronounced at low sugar concentrations. This stimulation was not seen in cells grown heterotrophically in the dark, suggesting that it is a transitory phenomenon which disappears during the autotrophy-heterotrophy growth transition. The stimulation of fructose assimilation by casein hydrolysate was abolished by chloramphenicol or streptomycin, suggesting there are rate-limiting steps in protein biosynthesis in the dark that ultimately lead to inhibition of fructose uptake. Glucose metabolism did not show these phenomena, indicating there are differences in the metabolism of the two sugars.
Cystine reductase in the dimorphic fungus Histoplasma capsulatum
Authors: Maresca B , Jacobson E , Medoff G , Kobayashi G
Published: January 2020

Organo-sulfur compounds favor the transition of mycelia of Histoplasma capsulatum to the yeast form (6, 8). Investigation of the role of cystine in the transition revealed that the two phases concentrated this amino acid at comparable rates and that mutants defective in the uptake of cystine were still able to undergo the transition normally. Uptake of cystine is therefore probably not a requirement for transition to or maintenance of the yeast phase. Both phases contained a reduced nicotinamide adenine dinucleotide phosphate-dependent glutathione reductase; but a reduced nicotinamide adenine dinucleotide-dependent cystine reductase was detectable only in the yeast phase. The cystine reductase appeared early in the transition of mycelium to yeast. Treatment of mycelia with p-chloromercuriphenylsulfonic acid, which prevented the transition to yeast, had no effect on cystine uptake but strongly inhibited the cystine reductase. These results suggest that cystine reductase may provide reduced sulfhydryl groups involved in the transition of mycelium to yeast.
Detergent-resistant variants of Bacillus subtilis with reduced cell diameter
Authors: Tilby M J
Published: January 2020

Variants of Bacillus subtilis resistant to the detergent Triton X-100 may exhibit: (i) normal cell morphology, (ii) reduced cell diameter, or (iii) helical cell shape. One variant of type ii was studied in some detail. Triton resistance, cell diameter reduction, and poor sporulation all may have resulted from a single mutation. High concentrations of Triton caused rapid lysis of wild-type cells. B. subtilis adapted to low Triton concentrations such that, upon subsequent exposure to higher concentrations, growth continued, although it bacame inhibited at very high concentrations. The variant studied retained its sensitivity to Triton-induced lysis but, after adaptation, grew at very high Triton levels. In this strain, cell diameter and cross-sectional area were reduced to about 73 and 50%, respectively, of those of wild type, yet the cells grew at normal rates, and DNA/protein/RNA ratios were largely unaltered. Peptidoglycan content per unit of cell surface area was higher in the variant than in the wild type under at least certain growth conditions.
Role of small molecules in regulation of D-serine deaminase synthesis
Authors: Heincz M C , McFall E
Published: January 2020

Cyclic AMP is required for optimal synthesis of D-serine deaminase synthesis from dsdO+ templates and for optimal hyperinducible synthesis from low constitutive dsdO templates both in vitro and in vivo. Neither D-serine, cyclic AMP, nor dsdC activator has an effect on expression of a high constitutive dsdO template. The synthesis of the dsdC activator itself in vitro is independent of cyclic AMP. Guanosine tetraphosphate does not have a significant effect on in vitro D-serine deaminase synthesis from dsdO+ or dsdO templates. A previously described class of dsdO mutants showing partial catabolite sensitivity of constitutive D-serine deaminase synthesis proved to be low dsdO types. They all contain a low constitutive dsdC mutation; the two effects are additive with regard to level of constitutivity, but only that portion of synthesis attributable to the dsdC mutation is cyclic AMP dependent.
Arginine biosynthesis in Neisseria gonorrhoeae: enzymes catalyzing the formation of ornithine and citrulline
Authors: Shinners E N , Catlin B W
Published: January 2020

Many of the Neisseria gonorrhoeae strains isolated from patients require arginine for growth in a defined medium. As a basis for genetic studies of these Arg- strains, we examined two biosynthetic enzymes of Arg+ (nonrequiring) gonococci. Cell-free extracts contained (i) glutamate acetyltransferase, which catalyzes the formation of L-ornithine from alpha-N-acetyl-L-ornithine, and (ii) ornithine transcaramylase, which catalyzes the reaction between L-ornithine and carbamyl phosphate, yielding L-citrulline. Arg- strains were unable to utilze alpha-N-acetyl-L-ornithine for growth lacked significant activity of glutamate acetyltransferase, and activity was gained by Arg+ clones derived by DNA-mediated transformation. Some of the Arg- patient isolates were unable to use either alpha-N-acetyl-L-ornithine or L-ornithine in place of arginine, and two separate steps of genetic transformation were required to yield Arg+ cells. Extracts of these doubly auxotrophic cells lacked glutamate acetyltransferase activity, but, unexpectedly, they displayed normal ornithine transcarbamylase activity. This finding illustrates the importance of identifying the products specified by arg loci during genetic studies of arginine auxotrophy.
Evidence for an intermediate in quinolinate biosynthesis in Escherichia coli
Authors: Wicks F D , Sakakibara S , Gholson R K
Published: January 2020

Evidence for the formation of an unstable intermediate in the synthesis of quinolinate from aspartate and dihydroxyacetone phosphate by Escherichia coli was obtained using toluenized cells of nadA and nadB mutants of this organism and partially purified A and B proteins in dialysis and membrane cone experiments. The results of these experiments indicate that the nadB gene product forms an unstable compound from aspartate in the presence of flavine adenine dinucleotide, and that this compound is then condensed with dihydroxyacetone phosphate to form quinolinate in a reaction catalyzed by the nadA gene product.
Heterogeneity and Distribution of Lipopolysaccharide in the Cell Wall of a Gram-Negative Marine Bacterium
Authors: DiRienzo Joseph M. , Deneke Carl F. , MacLeod Robert A.
Published: January 2020

Lipopolysaccharide (LPS) extracted from
Alteromonas haloplanktis
214, variants 1 and 3, separated into three fractions when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The fractions appeared in the gels as bands which stained for carbohydrate with the periodate-Schiff reagent. Variant 1, a smooth variant of the organism, and variant 3, a rough colonial variant, produced identical banding patterns. Under similar conditions, LPS from
Neisseria meningitidis
SDIC,
Escherichia coli
O111:B4, and
Salmonella typhimurium
LT2 gave rise to one, two, and three bands, respectively. LPS from
Pseudomonas aeruginosa
(ATCC 9027) failed to stain clearly with the reagent used. The banding pattern obtained with
A. haloplanktis
LPS was found not to be due to artifacts produced by the extraction or solubilization procedures employed or to the amount of protein associated with the LPS. When Triton X-100 replaced sodium dodecyl sulfate in the electrophoresis system, LPS failed to migrate into the gel. The lipid A but not the degraded polysaccharide fraction obtained by mild acid hydrolysis of the LPS migrated into the gel on electrophoresis. The three carbohydrate-staining bands obtained with
A. haloplanktis
LPS and referred to as LPS I, II, and III, in order of increasing electrophoretic mobility, were detected in each of the three outer layers of the cell wall of the organism. Estimations from densitometer scans indicated that 17% of the total LPS in the cell was present in the outer membrane, with the remainder divided almost equally between the loosely bound outer layer and the periplasmic space. Of the three fractions, LPS II was present in each of the layers in greatest amounts. Less LPS I and more LPS III were present in the outer membrane than in the periplasmic space. Pulse-labeling studies indicated that LPS I and II may be synthesized independently, whereas LPS III, which appeared only in cells in the stationary phase of growth, may be a degradation product of LPS I.
Purification and characterization of a tRNA methylase from Salmonella typhimurium
Authors: Pope W T , Reeves R H
Published: January 2020

A tRNA methylase, in which supK strains of Salmonella typhimurium are deficient, was purified from strain LT2 and characterized. Column chromatography of protein extracts from wild-type cells on phosphocellulose, diethylaminoethyl-Sephadex A-50, and hydroxlapatite resulted in an enzyme that was estimated to be about 50% pure. tRNA from S. typhimurium which had been incubated at pH 9.0 served as a substrate for this methylase. The enzyme has a molecular weight of about 50,000 as estimated by gel chromatography and by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels. The optimal assay conditions, as well as the kinetics and stability of the enzyme, were studied. As with other tRNA-methylating enzymes, S-adenosylhomocysteine is a potent inhibitor.
6-cyanopurine, a color indicator useful for isolating mutations in the nif (nitrogen fixation) genes of Klebsiella pneumoniae
Authors: MacNeil D , Brill W J
Published: January 2020

6-Cyanopurine (6-CP) can be used as a color indicator for certain classes of nif (N2 fixation) mutations in Klebsiella pneumoniae. Under N2-fixing conditions, Nif+ colonies and most Nif- colonies are purple on media containing 6-CP. Twenty-two Nif- mutants with altered color on medium containing 6-CP were isolated. All white mutants contained mutations in the regulatory genes, nifAA-nifL. Mutants which were more darkly colored than the wild type had mutations distributed among six nif genes. Medium with 6-CP was used to isolate Nif- mutants with deletions internal to the nif genes, and 6-CP was used to identify strains depressed for nitrogenase synthesis in the presence of NH4+.
Major outer membrane protein in Salmonella typhimurium induced by maltose
Authors: Palva E T
Published: January 2020

A maltose-induced major outer membrane protein (the 44K protein) is demonstrated in Salmonella typhimurium. This protein resembles the lambda receptor of Escherichia coli in its location, induction properties, apparent molecular weight, and association with the peptidoglycan layer of the cell wall. The 44K protein is missing in certain Salmonella Mal- mutants, which are also missing a protein analogous to the maltose-binding protein of E. coli. Thus, these mutants may be defective in the control of maltose genese in Salmonella. The proteins appear to be closely related, as indicated by cross-reaction of the Salmonella protein with the antiserum raised against the lambda receptor; however, they are not identical, since the peptide patterns obtained after limited proteolysis are completely different. Bacteriophage lambda does not use the 44K protein as a receptor.
Deletion plasmids from transformants of Pseudomonas aeruginosa trp cells with the RSF1010-trp hybrid plasmid and high levels of enzyme activity from the gene on the plasmid
Authors: Nagahari K
Published: January 2020

A RSF1010-trp hybrid plasmid which contained the tryptophan operon of Escherichia coli was introduced into Pseudomonas aeruginosa trp cells by transformation. From the Trp+ transformants several deletion plasmids were obtained, and their physical maps with restriction endonucleases were constructed. P. aeruginosa trp cells with these plasmids showed at first more than 100 times higher levels of tryptophan synthetase beta activity over that of the control P. aeruginosa wild-type cells, but these levels were drastically decreased by 1 week of successive transfers of cultures. This decrease in enzyme activity was found to be due to the change on the plasmids but not to the host cells. The production of E. coli tryptophan synthetase beta enzyme in P. aeruginosa cells was proved by immunological test.
Enchancement of nitrosoguanidine mutagenesis by chloramphenicol in Escherichia coli K-12
Authors: Sklar R
Published: January 2020

N-methyl-N'-nitro-N-nitrosoguanidine-induced mutagenesis in E. coli K-12 can be enchanced up to 50-fold by the addition of chloramphenicol with minimal effect on survival. Chloramphenicol does not produce the expected proportionate increase in closely linked double mutations.
Mechanism of colicin E3 production in strains harboring wild-type or mutant plasmids
Authors: Mock M , Schwartz M
Published: January 2020

As previously reported by others, more than 90% of the colicin E3 synthesized soon after induction of colicinogenic bacteria was found to be cell bound, about half of it being in a salt-extractable state at the cell surface. Evidence is presented that the colicin molecules remain preferentially bound to the cell which produced them, rather than being secreted and randomly distributed in the cell population. Secretion of colicin E3 may in fact never occur, all or most of the colicin found free in the medium perhaps being released during lysis of the producing cells long after induction. Among 19 mutant plasmids selected on the basis of their inability to produce an active colicin, only 3 were found to code for a protein which although it lacked any bactericidal activity, had the same molecular weight as wild-type colicin E3 and displayed a reaction of immunological identity with it. These three inactive colicins fail to be exported to the cell surface and seem to be blocked at some intermediate stage in the export process.
Restriction endonucleases: general survey procedure and survey of gliding bacteria
Authors: Mayer H , Reichenbach H
Published: January 2020

Among 120 strains of gliding bacteria which were screened for restriction endonucleases, 27 were found positive. Additionally, three strains carried enzymes able to release the supercoiled state of closed circular DNA. By using a new rapid method, restriction endonuclease activity was released by stirring about 0.5 g of cells (fresh weight) in a motor-driven glass homogenizer in buffer containing Triton X-101, ethylenediaminetetraacetic acid, and mercaptoethanol. A yield from 60 to 80% of the total activity present in the cells was obtained with minimal destruction of the cells. The enzyme activity in the crude extract was measured semi-quantitatively by digestion of DNA and subsequent separation of the fragments on an agarose slab gel. The method appears to be generally applicable for the extraction of restriction endonucleases from gram-negative bacteria on an analytical scale and in a modified form for large-scale preparation of restriction enzymes.
Pesticin-dependent generation of somotically stable spheroplast-like structures
Authors: Hall P J , Brubaker R R
Published: January 2020

Homogenous pesticin, a bacteriocin produced by Yersinia pestis, promoted rapid dose-dependent killing of Escherichia coli phi but permitted residual generation of cell mass. Both growing cells and those blocked in net synthesis of nucleic acids or protein were converted by pesticin to osmotically stable spheroplast-like forms. Morphology and viability of cells starved for fermentable carbohydrate were not affected by pesticin. Similar spheroplast-like structures were formed from sensitive cells of Yersinia pseudotuberculosis, Yersinia enterocolitica, and Y. pestis.
Isolation and characterization of Caulobacter crescentus flagellar hooks
Authors: Lagenaur C , DeMartini M , Agabian N
Published: January 2020

The basal hook structure of the flagellar organelle Caulobacter crescentus was isolated from release flagella. Hook preparations contained a single major proteins species of 73,000 molecular weight and proteins in smaller amounts that may be minor hook components. Hooks isolated from C. crescents CB13B1a and CB15 were immunologically cross-reactive.
Comparison of lipids from Spiroplasma citri and corn stunt spiroplasma
Authors: Patel K R , Smith P F , Mayberry W R
Published: January 2020

The qualitative lipid composition of Spiroplasma citri and corn stunt spiroplasma is identical. Small amounts of acylated glucose and steryl glucoside were found.
Chromosomal superkiller mutants of Saccharomyces cerevisiae
Authors: Toh-E A , Guerry P , Wickner R B
Published: January 2020

Yeast strains carrying a 1.5 X 10(6)-dalton double-stranded RNA in virus-like particles secrete a protein toxin which is lethal to strains not carrying this species of double-stranded RNA. We find that recessive mutations in any of four chromosomal genes result in the superkiller phenotype, i.e., increased secretion of killer toxin activity by strains carrying the killer genome. These genes are designated ski1 through ski4 (for superkiller), ski3 and ski4 are located on chromosome XIV, and ski1 is on chromosome VII. A ski1 mutation results in a decreased rate of cell growth. The kex1 and kex2 mutations are epistatic to each ski mutation.
Incorporation of 32Pi into nucleotides, polyphosphates, and other acid-soluble compounds by Myxococcus xanthus during myxospore formation
Authors: Maeba P Y , Shipman R
Published: January 2020

When glycerol was used to induce myxospore formation in Myxococcu xanthus in the presence of 32Pi, the label was incorporated into a variety of acid-soluble compounds. Incorporation into ribonucleotides was approximately fivefold greater than in vegetative cells or noninducible mutants grown in glycerol. The label was also incorporated into some unknown compounds and material tentatively identified as guanosine tetraphosphate. Marked accumulation into polyphosphates, which were present mainly in culture supernatants, occurred relatively late during myxospore formation. The kinetics of accumulation of some of these compounds and their distribution into acid-soluble cell extracts and culture supernatants are described and compared with those in vegetative cells and noninducible mutants.
Isolation and characterization of extragenic suppressor strains of Corynebacterium diphtheriae
Authors: Bacha P , Murphy J R
Published: January 2020

The isolation and characterization of two different nonsense suppressor strains of Corynebacterium diphtheriae C7 sup+(-)tox- are described. Appropriate lysogens of these strains with corynephage beta, carrying known class II tox premature polypeptide chain termination mutations [C7sup-1(betatox-30) and C7sup-2(betatox-45)], each produce a 62,000-dalton polypeptide with nicotinamide adenine dinucleotide: elongation factor-2 adenosine diphosphate ribosyltransferase activity in addition to a chain-terminated polypeptide of 30,000 or 45,000 daltons, respectively. In addition, purified protein of 62,000 daltons, resulting from the suppression of the nonsense mutations tox-30 and tox-45, will react with antisera purified against the terminal 17,000 daltons of the toxin molecule and are immunologically identical to toxin by radial immunodiffusion. The suppression pattern of lysogenic derivatives of C7sup-1(-)tox- and C7sup-2(-)tox- with other class II and III mutants of corynephage beta was determined.
Bypass of receptor-mediated resistance to colicin E3 in Escherichia coli K-12
Authors: Tilby M , Hindennach I , Henning U
Published: January 2020

Colicin E3 was found to kill, under conditions of osmotic shock, cells lacking a functional outer membrane receptor (bfe). Under such conditions, component A of the colicin, carrying endonucleolytic activity, also killed bfe cells, whereas fragment T2, obtained by tryptic digestion of the colicin and also active endonucleolytically, was inactive. Tolerance to the colicin caused by defects in the outer membrane could be overcome by osmotic shock, whereas tolerance probably caused by an altered plasma membrane could not.
Cell wall assembly in Bacillus subtilis: location of wall material incorporated during pulsed release of phosphate limitation, its accessibility to bacteriophages and concanavalin A, and its susceptibility to turnover
Authors: Anderson A J , Green R S , Sturman A J , Archibald A R
Published: January 2020

Addition of a pulse of phosphate to a phosphate-limited chemostat culture of Bacillus subtilis W23 led to the synthesis of teichoic acid and the consequent development by the bacteria of the ability to bind phage SP50. In cultures growing at different rates, phage-binding properties became maximal approximately one generation time after addition of the pulse. Removal of the incorporated teichoic acid by turnover also reached its maximum rate after a similar interval. After pulsed release of phosphate limitation in B. subtilis NCTC 3610, the alpha-glucosyl residues of the incorporated teichoic acid, detected by their interaction with concanavalin A, became maximally exposed at the same time that phage binding was maximum. At that time the bacteria bound phage all over the cylindrical part of the surface and at about one-third of the polar caps. That fraction of the receptor material that is exposed soon after its incorporation was distributed along the cylindrical length of most of the bacteria, but few phages bound to the polar caps, except in the case of short bacteria; these bound phages in a markedly asymmetric manner at one pole and along their length. The significance of these results is discussed in relation to the mode of assembly of the cell wall.
Metabolism of phenol and resorcinol in Trichosporon cutaneum
Authors: Gaal A , Neujahr H Y
Published: January 2020

Trichosporon cutaneum was grown with phenol or resorcinol as the carbon source. The formation of beta-ketoadipate from phenol, catechol, and resorcinol was shown by a manometric method using antipyrine and also by its isolation and crystallization. Metabolism of phenol begins with o-hydroxylation. This is followed by ortho-ring fission, lactonization to muconolactone, and delactonization to beta-ketoadipate. No meta-ring fission could be demonstrated. Metabolism of resorcinol begins with o-hydroxylation to 1,2,4-benzenetriol, which undergoes ortho-ring fission yielding maleylacetate. Isolating this product leads to its decarboxylation and isomerization to trans-acetylacrylic acid. Maleylacetate is reduced by crude extracts to beta-ketoadipate with either reduced nicotinamide adenine dinucleotide or reduced nicotinamide adenine dinucleotide phosphate as a cosubstrate. The enzyme catalyzing this reaction was separated from catechol 1,2-oxygenase, phenol hydroxylase, and muconate lactonizing enzyme on a diethyl-aminoethyl-Sephadex A50 column. As a result it was purified some 50-fold, as was the muconate-lactonizing enzyme. Methyl-, fluoro-, and chlorophenols are converted to a varying extent by crude extracts and by purified enzymes. None of these derivatives is converted to maleylacetate, beta-ketoadipate, or their derivatives. Cells grown on resorcinol contain enzymes that participate in the degradation of phenol and vice versa.
Hydrogen-Dependent Nitrogenase Activity and ATP Formation in
Rhizobium japonicum
Bacteroids
Authors: Emerich David W. , Ruiz-Argüeso Tomás , Ching Te May , Evans Harold J.
Published: January 2020

Rhizobium japonicum
122 DES bacteroids from soybean nodules possess an active H
2
-oxidizing system that recycles all of the H
2
lost through nitrogenase-dependent H
2
evolution. The addition of 72 μM H
2
to suspensions of bacteroids increased O
2
uptake 300% and the rate of C
2
H
2
reduction 300 to 500%. The optimal partial pressure of O
2
was increased, and the partial pressure of O
2
range for C
2
H
2
reduction was extended by adding H
2
. A supply of succinate to bacteroids resulted in effects similar to those obtained by adding H
2
. Both H
2
and succinate provided respiratory protection for the N
2
-fixing system in bacteroids. The oxidation of H
2
by bacteroids increased the steady-state pool of ATP by 20 to 40%. In the presence of 50 mM iodoacetate, which caused much greater inhibition of endogenous respiration than of H
2
oxidation, the addition of H
2
increased the steady-state pool of ATP in bacteroids by 500%. Inhibitor evidence and an absolute requirement for O
2
indicated that the H
2
-stimulated ATP synthesis occurred through oxidative phosphorylation. In the presence of 50 mM iodoacetate, H
2
-dependent ATP synthesis occurred at a rate sufficient to support nitrogenase activity. The addition of H
2
to H
2
uptake-negative strains of
R. japonicum
had no effect on ATP formation or C
2
H
2
reduction. It is concluded that the H
2
-oxidizing system in H
2
uptake-positive bacteroids benefits the N
2
-fixing process by providing respiratory protection of the O
2
-labile nitrogenase proteins and generating ATP to support maximal rates of C
2
H
2
reduction by oxidation of the H
2
produced from the nitrogenase system.
ATP Sulfurylase from
Penicillium chrysogenum:
Is the Internal Level of the Enzyme Sufficient to Account for the Rate of Sulfate Utilization?
Authors: Farley John R. , Mayer Stephanie , Chandler Carol J. , Segel Irwin H.
Published: January 2020

The in vivo rate of sulfate activation in
Penicillium chrysogenum
(wild-type strain ATCC 24791) was determined to be 0.19 ± 0.09 μmol g
−1
(dry weight) min
−1
by the following methods. (i) The maximum growth of the organism in synthetic medium was a linear function of the initial Na
2
SO
4
concentration between 0 and 8 × 10
−4
Na
2
SO
4
. The growth yield was 1.64 × 10
−2
g (dry weight) of mycelium per μmol of added sulfate, corresponding to a minimum sulfur requirement of 61 μmol/g (dry weight). Under these conditions (limiting sulfate) the minimum doubling time of
P. chrysogenum
in submerged culture was about 3.8 h, corresponding to a maximum exponential growth rate constant of 3.0 × 10
−3
min
−1
. If all the sulfur in this mycelium passed through adenosine-5′-phosphosulfate, the rate of sulfate activation in vivo must have been 0.183 μmol min
−1
g
−1
(dry weight). (ii) In the presence of excess
35
SO
4
2−
, the total organic
35
S produced varied with the mycelial growth rate. However, until the culture approached maximum density, the product of [(growth rate constant) × (organic
35
S content)] was nearly constant at 0.24 to 0.28 μmol min
−1
g
−1
(dry weight). (iii) A sulfur-starved mycelium pulsed with 10
−4
M
35
SO
4
2−
produced organic
35
S at a rate of about 0.10 μmol min
−1
g
−1
(dry weight) under conditions where the internal concentrations of ATP and sulfate would permit ATP sulfurylase to operate at about 70% of its

V
max

. Cell-free extracts of
P. chrysogenum
growing rapidly on excess sulfate contained 0.22 U of ATP sulfurylase per g (dry weight). Thus, in spite of the relatively low specific activity of homogeneous ATP sulfurylase (0.13 U/mg of protein, corresponding to an active site turnover of 7.15 min
−1
), the mycelial content of the enzyme was sufficient to account for the observed growth rate of the organism on inorganic sulfate as the sole sulfur source.
alpha-Ketoglutarate dehydrogenase mutant of Rhizobium meliloti
Authors: Duncan M J , Fraenkel D G
Published: January 2020

A mutant of Rhizobium meliloti selected as unable to grow on L-arabinose also failed to grow on acetate or pyruvate. It grew, but slower than the parental strain, on many other carbon sources. Assay showed it to lack alpha-ketoglutarate dehydrogenase (kgd) activity, and revertants of normal growth phenotype contained the activity again. Other enzymes of the tricarboxylic acid cycle and of the glyoxylate cycle were present in both mutant and parent strains. Enzymes of pyruvate metabolism were also assayed. L-Arabinose degradation in R. meliloti was found to differ from the known pathway in R. japonicum, since the former strain lacked 2-keto-o-deoxy-L-arabonate aldolase but contained alpha-ketoglutarate semialdehyde dehydrogenase; thus, it is likely that R. meliloti has the L-arabinose pathway leading to alpha-ketoglutarate rather than the one to glycolaldehyde and pyruvate. This finding accounts for the L-arabinose negativity of the mutant. Resting cells of the mutant were able to metabolize the three substrates which did not allow growth.
Effect of ethylenediaminetetraacetate on phospholipids and outer membrane function in Escherichia coli
Authors: Hardaway K L , Buller C S
Published: January 2020

Treatment of Escherichia coli K-12 strain S15, containing a normal amount of phospholipase A, with ethylenediaminetetraacetate (EDTA) resulted in an increase in sensitivity of the organism to actinomycin D. Strain S17, a mutant deficient in both detergent-resistant phospholipase A and detergent-sensitive phospholipase A, was considerably less sensitive to the antibiotic after the treatment. Both strains released lipopolysaccharide after EDTA treatment, indicating that this outer membrane component alone is not the barrier to actinomycin in these organisms. The phospholipase A-deficient strain released less alkaline phosphatase, a periplasmic enzyme. EDTA treatment of S15 resulted in the accumulation of free fatty acids, indicative of phospholipase A activation. Cells briefly treated with EDTA regained the barrier to actinomycin when incubated in growth media, and the cessation of the accumulation of free fatty acids was in approximate temporal agreement with restoration of the barrier. Cells in which phospholipase A was activated by brief exposure to EDTA synthesized relatively more phosphatidylethanolamine than did untreated cells in the initial period after dilution into growth media. These experiments suggest that the EDTA-induced loss of outer membrane barrier function of E. coli K-12 is mediated through the activation of phospholipase A.
Method for isolating restriction- and modificationless mutants of Escherichia coli K-12
Authors: Del Giudice L
Published: January 2020

A simple method is described for the selection and isolation of restriction- and modificationless mutants in Escherichia coli K-12 by using the following properties: (i) the temperature-sensitive repressor activity of phage lambdacI857; (ii) a mutant of lambda phage defective in integration and the establishment of repression (lambdab2cI); (iii) a virulent lambda phage insensitive to the repressor activity. The final yield of spontaneously arising rk-mk+ and rk-mk- mutants from stationary-phase cultures was about 5% of the surviving cells.
Fimbriae of Escherichia coli K-12 strain AW405 and related bacteria
Authors: Clegg S , Old D C
Published: January 2020

Fimbriate strains of Escherichia coli K-12 of the AW405 series agglutinated erythrocytes of several animal species. The hemagglutination was mannose senstivie, and the fimbriae were type 1. When cultured for extended periods in static broths, they did not form fimbrial pellicles but formed thick, nonfimbrial pellicles, the appearance of which was not associated with the selective outgrowth of fimbriate-phase bacteria.
"Self-catabolite repression" of pectate lyase in Erwinia carotovora
Authors: Tsuyumu S
Published: January 2020

The induction of pectate lyase of Erwinia carotovora was repressed by a high concentration of its inducer. The concomitant addition of cyclic adenosine 3',5'-monophosphate reversed this repression.
Transport of alpha-p-nitrophenylgalactoside by the lactose carrier of Escherichia coli
Authors: Putzrath R M , Wilson T H
Published: January 2020

alpha-p-Nitrophenylgalactoside was found to be accumulated by the lactose transport-system of Escherichia coli. This fact may help to resolve the differences in the reported number of sugar binding sites of the lactose transport protein in nonenergized and energized membrane vesicles.
A Fifth Gene (
uncE
) in the Operon Concerned with Oxidative Phosphorylation in
Escherichia coli
Authors: Downie J. A. , Senior A. E. , Gibson F. , Cox G. B.
Published: January 2020

Three mutant
unc
alleles (
unc-408, unc-410
, and
unc-429
) affecting the coupling of electron transport to oxidative phosphorylation in
Escherichia coli
K-12 have been characterized. Genetic complementation analyses using previously defined mutant
unc
alleles indicated that the new mutant
unc
alleles affect a previously undescribed gene designated
uncE
. The phenotype of strains carrying the
uncE408
or
uncE429
allele is similar in that Mg
2+
-adenosine triphosphatase activity is only found in the cytoplasmic fraction, and membranes do not bind the F
1
portion of adenosine triphosphatase purified from a normal strain. In contrast, adenosine triphosphatase activity is present both in the cytoplasm and on the membranes from a strain carrying the
unc-410
allele, and normal F
1
binds to F
1
-depleted membranes from this strain. The adenosine triphosphatase solubilized from membranes of a strain carrying the
unc-410
allele reconstituted ATP-dependent membrane energization in F
1
-depleted membranes from a normal strain. Genetic complementation tests using various Mu-induced
unc
alleles in partial diploid strains show that the
uncE
gene is in the
unc
operon and that the order of genes is
uncB E A D C
. The
unc-410
allele differs from the
uncE408
and
uncE429
alleles in that complementation tests with the Mu-induced
unc
alleles indicate that more than one gene is affected. It is concluded that this is due to a deletion which includes part of the
uncE
gene and another gene, or genes, between the
uncE
and
uncA
genes.
Physiological responses of bacteria to cytochalasin A: effects on growth, transport, and enzyme induction
Authors: Cunningham D , Schafer D , Tanenbaum S W , Flashner M
Published: January 2020

Cytochalasin A at 5 to 25 microgram/ml (1.0 x 10(-5) to 5.2 x 10(-5) M) inhibited the growth of three gram-positive bacteria, Arthrobacter sialophilus, Staphyloccus aureus, and Bacillus amyloliquifaciens, but had little or no effect on the growth of three gram-negative bacteria, Excherichia coli, Pseudomonas maltophilia, and Aeromonas proteolytica. A. sialophilus and S. aureus recovered spontaneously from cytochalasin A-mediated growth inhibition after a considerable lag period, which was dependent on the drug dose. It was demonstrated that this long-term recovery did not involve selection of resistant variants. Cytochalasin A had no detrimental effect on cell viability in A. sialophilus or S. aureus, but caused lysis of B. amyloliquifaciens. The drug prevented enzyme inductions and inhibited transport of valine, uridine, and glucose in the gram-positive organisms. It had little or no effect on these processes in the gram-negative organisms. In studies with A. sialophilus, the drug inhbitied respiration of exogenous substrates, but did not depress endogenous respiration. These results constitute the first unequivocal evidence for the bacteriostatic properties of this class of compounds and indicate that cytochalasin A halts various physiological processes in gram-positive bacteria primarily by inhibiting solute transport.