bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel genotypes among transductants made with bacteriophage P1 lysates from an F14 merogenote strain of Escherichia coli K-12
Authors: Hendrickson E R , Duggan D E
Published: January 2020

Among P1 transductants in Escherichia coli K-12 that were selected for the proximal and distal markers from the large F14 merogenote, a variety of unusual genotypes were found. As earlier workers had found, one class of these could transfer the proximal genes (argH, metB) and distal genes (ilvEDAC) of the F14 during conjugation. These F14 genes could be transferred into RecA recipients, indicating that they were carried on an F-merogenote rather than on an Hfr chromosome. The transduced F-merogenotes could transfer other F14 genes (metE, rha) as well. Transfer kinetic analysis showed that all of the latter transduced F-merogenotes that were examined were indistinguishable from the parental F14 in the order of transfer and the genetic distance between proximal and distal markers. This suggests that the whole F14 had been received somehow by the primary transductional recipients, a remarkable possibility since the F14 is much larger than the largest deoxyribonucleic acid segment normally transduced by P1. The mechanism of this phenomenon is not yet known. Many of the transductants did not transfer any of the F14 markers tested. Some of these transductants segregated certain F14 genes, indicating they were carried on self-replicating genetic elements, but others were not cured of F14 markers, even by acridine orange. Cotransductional analysis of this group was consistent with the hypothesis that the F14 markers in some of these strains had integrated into the chromosome in the expected manner, since in these latter the F14 alleles were linked to the expected chromosomal genes. Other strains among the stable transductants had acquired new linkages in that genes previously separated by several minutes could now be cotransduced. These latter included the novel cotransductional linkages of rbs-ilv-argH, rbs-ilv-argH-metB, and ilvD-argH-purD. Such strains might have been formed as a result of insertion into the chromosome of small circles derived from F14.
Polygalacturonic acid trans-eliminase in the osmotic shock fluid of Erwinia rubrifaciens: characterization of the purified enzyme and its effect on plant cells
Authors: Gardner J M , Kado C I
Published: January 2020

An endopolygalacturonic acid trans-eliminase (EC 4.2.2.2), released by osmotic shock of Erwinia rubrifaciens cells, has been purified to near homogeneity (3, 100-fold) by column chromatography on diethylaminoethyl-cellulose, phosphocellulose, and hydroxyapatite-cellulose followed by isoelectric focusing. It has a molecular weight of 41,000, s20,w of 3.09S, an isoelectric point of pH 6.25, pH optimum of 9.5, and a temperature optimum of 37 C and requires Ca2+ with an optimum concentration of 0.5 to 1.0 mM. Mg2+ could not substitute for Ca2+. Tyrosinyl residues seem essential for enzyme catalysis based on rapid inactivation by tetranitromethane. The enzyme prefers unmethylated polygalacturonic acid as the substrate, cleaving alpha-1,4-glycosidic linkages randomly to form unsaturated galacturonides at a Vmax of 1,166 mumol of product/min per mg of protein and a Km of 5 mg of polygalacturonic acid per ml. Over 90% of the enzyme activity is released from osmotically shocked E. rubrifaciens cells. Unlike E. rubrifaciens, trans-eliminase is not released from Erwinia carotovora cells by osmotic shock treatment, but enzyme activity is detected in the culture medium. The release of the enzyme is reduced fivefold by the addition of dibutyryl cyclic adenosine 5'-monophosphate. The hypersensitive reaction in tobacco leaves was induced within 60 min after injection of less than 1 mug of purified E. rubrifaciens trans-eliminase. Single cells of tobacco in suspension culture are readily killed by the enzyme, whereas tobacco protoplasts remain unaffected when treated in the same manner. These results indicate that endopolygalacturonic acid trans-eliminase is a constitutive enzyme possibly located in the periplasmic space of the E. rubrifaciens cell and releases enzyme into the culture medium in the presence of substrate. The release of the enzyme in tobacco tissue and the trans-eliminative cleavage of plant cell wall components may be steps leading to hypersensitivity of the tobacco tissue.
Genetic and physiological regulation of intrinsic proteins of the outer membrane of Salmonella typhimurium
Authors: Bennett R L , Rothfield L I
Published: January 2020

Four major outer membrane polypeptides, accounting for approximately 20% of the total protein of the outer membrane of Salmonella typhimurium, were induced by growth in minimal medium. The polypeptides were tightly bound membrane components. Physiological and genetic evidence indicates that the four polypeptides fall in two separate regulation groups. Synthesis of one of these groups was coordinately regulated by the concentration of iron in the medium, and a mutant strain has been identified in which there is constitutive synthesis of this group of major outer membrane proteins.
Lipoprotein from the outer membrane of Escherichia coli: purification, paracrystallization, and some properties of its free form
Authors: Inoyye S , Takeishi K , Lee N , DeMartini M , Hirashima A , Inouye M
Published: January 2020

In the envelope of Escherichia coli, is a lipoprotein of molecular weight 7,200 as a major envelope protein. This lipoprotein was previously shown to exist in two different forms in the outer membrane of E. coli: the free form and the boundform, which is covalently linked to the peptidoglycau. The free form of the lipoprotein has been purified and paracrystallized by adding acetone to a sodium dodecyl sulfate solution in the presence of magnesium ion. The paracrystals were needle shaped. An electron micrograph of the negatively stained paracrystals showed a highly ordered ultrastructure. The chemical structure of the free form was compared with that of the bound form by (i) the amino acid composition, (ii) the fatty acid composition, and (iii) the peptide analysis after cyanogen bromide cleavage. The alpha-helical content of the free form of the lipoprotein was measured from the circular dichroism spectrum of the lipoprotein in 0.01% sodium dodecyl sulfate and found to be 87%. Using the purified lipoprotein as antigen, antiserum against the free form of the lipoprotein was obtained. Immunoprecipitation of the lipoprotein with the antiserum was found to be very specific, since only the free form of the lipoprotein was found as a major peak when the antiserum was reacted with the whole envelope proteins solubilized in 0.2% sodium dodecyl sulfate, and the immunoprecipitate thus formed was analyzed by polyacrylamide gel electrophoresis.
Cellular Localization of Uridine 5′-Diphosphate-
N
-Acetyl-
d
-Glucosamine Oxidoreductase Activity in
Citrobacter freundii
Authors: Wheat Robert W. , Barrow Robert O. , Land Geoffrey A.
Published: January 2020

The uridine 5′-diphosphate-
N
-acetyl-
d
-glucosamine oxidoreductase activity of
Citrobacter freundii
ATCC 10053 was found to be located in the soluble cytoplasmic fraction of lysed spheroplasts.
Characterization of the N-acetylmuramic acid L-alanine amidase from Bacillus subtilis
Authors: Lindsay B , Glaser L
Published: January 2020

The N-acetylmuramic acid L-alanine amidase from Bacillus subtilis W-23 has been purified to apparent homogeneity. The enzyme is a monomer of molecular weight 51,000, which binds extremely tightly to homologous cell walls but not to heterologous cell walls, even of the closely related strain B. subtilis ATCC 6051. This difference in binding is only in part due to differences in teichoic acid between these two strains and to a large extent appears to represent differences in the arrangement of the peptidoglycan. A comparison of the amidase from B. subtilis W-23 and the enzyme previously purified from B. subtilis ATCC 6051 (Herbold and Glaser, 1975) shows that the two proteins, which cleave the same bond and are of the same size, do not cross-react immunologically and that the two enzymes are, therefore, not closely related in structure.
Electron microscope study of a plasmid chimera containing the replication region of the Escherichia coli F plasmid
Authors: Guyer M S , Figurski D , Davidson N
Published: January 2020

pML31, a plasmid chimera constructed to contain the replication genes of an Flac plasmid, has been studied by electron microscope methods. Heteroduplex analysis shows that the only F sequence present in pML31 is that with corrdinates 40.3-49.3F. This region has previously been identified as essential for plasmid maintenance. The sequence of pML31, which was derived originally from R6-5, carries the km gene(s) and an inverted duplication of a 1.0-kilobase sequence. On the basis of length measurements, the repeated sequence is different from IS1, IS2, IS3, and an inverted repeat associated with the km gene(s) of plasmid JR67.
Effect of chloramphenicol on the electron systems in Ustilago cynodontis
Authors: Durieu-Trautmann O , Tavlitzki J
Published: January 2020

The mycelial cells of Ustilago cynodontis possess at least two electron transport systems: a cyanide-sensitive cytochrome pathway, which represents the major route for electron transport, and an alternative cyanide-insensitive pathway, inhibited by salicylhydroxamic acid. In the presence of chloramphenicol in the culture medium, mycelial cells respire only by the alternatuve chain. The stable induced yeast-like cells, obtained by prolonged chloramphenicol treatment of the mycelial cells, respire as the untreated mycelial cells; this result indicates that the phenotypic change induced by chloramphenicol is not related to a modification of the respiratory system.
Permeability measurements on mitochondria from wild-type and poky strains of Neurospora crassa
Authors: Katkocin D M , Slayman C W
Published: January 2020

The permeability properties of isolated Neurospora mitochondria were determined by measuring the rate at which the mitochondria swell in isotonic solutions of various organic and inorganic molecules. Like mammalian mitochondria, wild-type Neurospora mitochondria were impermeable to sucrose and only slightly more permeable to most inorganic ions (K, Na, Cl). Their permeability to K was greatly increased by valinomycin and by monensin. In addition, the mitochondria contain specific systems mediating PO4 uptake and PO4- malate, fumarate, and succinate exchange. Mitochondria from the maternally inherited poky strain of Neurospora, previously demonstrated to possess defective ribosomes and a grossly cytochrome chain, showed a slight but significant increase in permeability to inorganic ions. They contained, however, the specific uptake and exchange systems for phosphate and dicarboxylate anions, a result suggesting that these systems do not depend upon mitochondrially synthesized polypeptides.
Novel mutation that causes a structural change in a lipoprotein in the outer membrane of Escherichia coli
Authors: Suzuki H , Nishimura Y , Iketani H , Campisi J , Hirashima A
Published: January 2020

A novel mutation which caused a structural change in a lipoprotein in the outer-membrane has been found in Escherichia coli K-12. The lipoprotein of the wild-type strain is known to have a peculiar amino terminal structure: glycerylcysteine with two fatty acids attached by ester linkages and one fatty acid by an amide linkage. In contrast to the wild-type lipoprotein, the mutant lipoproteins is isolated from the E. coli envelope as a dimer of molecular weight of about 15,000. The dimer can be reduced by mercaptoethanol to the lipoprotein monomer of molecular weight of about 7,500. The monomer has a free thiol group which is susceptible to monoiodacetie mutant lipoprotein is extremely low in comparison with that into the wild-type lipoprotein. These results suggest that the mutant is defective in transferring a glycerol group to the thiol group of the amino terminal cysteine residue of the lipoprotein. The gene responsible for this modification reaction has been located at 36.5 min on the E. coli chromosome.
Nearest-Neighbor Analysis of
Escherichia coli
Outer Membrane Proteins, Using Cleavable Cross-Links
Authors: Palva E. T. , Randall L. L.
Published: January 2020

A specific dimer of the 37,000-dalton, major outer membrane protein was demonstrated by chemical cross-linking with cleavable reagents.
Release of enzymes by normal and wall-free cells of Chlamydomonas
Authors: Loppes R
Published: January 2020

The phosphatase produced by the wild-type strain of Chlamydomonas reinhardi in media deprived of inorganic phosphate are found partly inside and partly outside the cells. The same enzymes are almost completely released by a mutant strain defective in cell wall formation. It is proposed that the failure of cell wall mutants to survive in certain conditions is related to their inability to retain certain essential compounds that are normally associated to the cell wall.
Localization of tetramethylphenylenediamine-oxidase in the outer cell wall layer of Neisseria meningitidis
Authors: Devoe I W , Golchrist J E
Published: January 2020

A highly active tetramethylphenylenediamine-oxidase has been found in association with the cell wall blebs, evaginations of the outer wall membrane, of Neisseria meningitidis. Isolated wall blebs consumed oxygen in the presence of ascorbate-tetramethylphenylenediamine but not in the presence of succinate, whereas cell envelope preparations are active in both substrates. The ratio of succinate dehydrogenase/tetramethylphenylenediamine-oxidase activities in preparations of envelopes was approximately 100 times that in isolated wall blebs, indicating that the outer membrane preparations were highly purified.
Teichoic acids and lipids associated with the membrane of a Bacillus licheniformis mutant and the membrane lipids of the parental strain
Authors: Button D , Hemmings N L
Published: January 2020

Bacillus licheniformis 6346 MH-1 and a phosphoglucomutase-deficient poorly lytic mutant, B. licheniformis 6346 MH-5, both contain cardiolipin, phosphatidyl ethanolamine, and phosphatidyl glycerol but are devoid of phosphoglycolipids. Gentiobiosyl diglyceride is present in the parent organism but glycolipids are absent from the mutant. Lipoteichoic acid was extracted from the whole cells of MH-5 with hot aqueous phenol and contained fatty acids, glucosamine, and 1,3-polyglycerol phosphate. The fatty acids were predominantly of the branched-chain type and were esterified to hydroxyl groups of a terminal glycerol residue. The polyglycerol phosphate chains contained, on average, 32 to 40 glycerol residues, some of which were substituted at the secondary hydroxyl group with alpha-N-acylglucosaminyl residues. Phenol extraction of the supernatant fluid that remained when walls were removed from preparations of disrupted cells of MH-5 yielded membrane teichoic acid, which consisted of substituted polyglycerol phosphate but was devoid of fatty acids.
Stimulatory effect of lithium ion on proline transport by whole cells of Escherichia coli
Authors: Kayama Y , Kawasaki T
Published: January 2020

The effect of monovalent cations on proline transport in whole cells of Escherichia coli K-12 has been examined. Lithium ion added to the uptake medium stimulated proline transport severalfold and K+ and Na+ were slightly effective, whereas Rb+, Cs+, and NH4+ were completely without effect. The stimulatory effect of Li+ on proline transport was not due to an increase in osmolarity of the uptake medium, and d 5 mM p-chloromercuribenzene sulfonic acid completely blocked this effect of Li+ without having any effect on the basal rate of proline transport. The Arrhenius plots for Li+-stimulated transport showed a clear transition point at 35 degrees C in addition to 20 degrees C which was also detectable in the basal transport. Lithium ion stimulated proline transport synergistically in the presence of glucose and succinate as a carbon source. The addition of 2.5 mM KCN or 0.5 mM arsenate did not inhibit this synergistic effect, although the presence of these inhibitors inhibited completely the stimulation of proline transport induced by the addition of carbon source. Carbonylcyanide m-chlorophenylhydrazone and 2,4-dinitrophenol blocked both the basal and Li+-stimulated proline transport. When membrane potential of E. coli cells was measured by the dibenzyldimethylammonium uptake method, the incubation of Li+ with the cells did not affect the preexisting membrane potential. These results suggest that Li+ stimulates proline transport by intact cells of E. coli in a manner somewhat affecting membrane component(s) different from the transport carrier of proline. It is uncertain whether the effect of Li+ is directly involved in the mechanisms of energy coupling of proline transport.
Pleiotropic, extragenic suppression of dna mutants in Bacillus subtilis
Authors: Siccardi A G , Ottolenghi S , Fortunato A , Mazza G
Published: January 2020

Thermosensitive (dna) mutants of Bacillus subtilis defective in deoxyribonucleic acid replication can be divided into two groups on the basis of their ability to spontaneously yield secondary mutants with an HDS phenotype (thermoin-sensitivity and resistance to aryl-azo-pyrimidines) at frequencies higher than 10(-8). Such a phenotype is due to alleles at the hds locus (mapping close to cysA), which act as extragenic pleiotropic suppressors. HDS suppressibility has been used as a screening tool to identify new dna strains among uncharacterized temperature-sensitive mutants.
Postirradiation recovery dependent on the uvr-1 locus in Bacillus subtilis
Authors: Hadden C T
Published: January 2020

A mutant (uvr-1) of Bacillus subtilis that is deficient in excision of ultraviolet (UV)-induced pyrimidine dimers from deoxyribonucleic acid (DNA) shows a marked increase in ability to survive UV irradiation when plated on amino acid-supplemented agar medium compared with its survival ability when plated on nutrient plating medium, the effect is considered to be one of growth-dependent lethality. Irradiated stationary phase uvr-1 cells, incubated in liquid medium lacking amino acids required for growth, recover from this sensitivity to rich medium within 3 to 4 h after irradiation. Recovery is greatly reduced in the absence of glucose oiminated. Exponentially growing cells have a limited ability to recover from sensitivity to rich medium. Growth-dependent lethality can also occur in liquid medium. In nutrient broth the ability of irradiated stationary-phase uvr-1 cells to form colonies on defined agar medium decreases during postirradiation incubation, but treatmeth with chloramphenicol inhibits the loss of colony-forming ability. Recovery from sensitivity to rich media is inhibited by caffeine but not by 6-(p-hydroxyphenylazo)-uracil, and inhibitor of DNA replication. Alkaline sucrose gradient profiles show that conditions allowing recovery also favor maintaining intact DNA strands, whereas DNA strand breakage or degradation is associated with loss of viability. Recovery from sensitivity to rich medium has not been observed in the Ur+ parent or in strains carrying the mutations uvs-42 (another deficiency in dimer excision), recA1, or polA59. A uvr-1 recA1 mutants shows a higher level of recovery than does the recA1 single mutant, but a much lower level than the uvr-1 single mutant. Apparently, both the uvr-1 defect and Rec+ and PoII+ functions are essential for recovery from sensitivity to rich medium. For optimal recovery, growth immediately after irradiation must be delayed. The process requires energy, apparently involves recombination, and probably results in rejoining of DNA strands in which incision but not excision has occurred.
Escherichia coli ornithine carbamolytransferase isoenzymes: evolutionary significance and the isolation of lambdaargF and lambdaargI transducing bacteriophages
Authors: Legrain C , Stalon V , Glansdorff N
Published: January 2020

Among the Enterobacteriaceae, Escherichia coli K-12 is the only strain known to have two structural genes (argF and argI) for ornithine carbamoyltransferase. The two gene products interact to form a family of four functional isoenzymes, respectively designated FFF, FFI, FII, and III. The FFF and III isoenzymes exhibit nearly identical kinetic parameters in the conditions applied. FFF is more thermolabile than III; this allows the straightforward characterization of new transducing phages carrying either argF or argI. The bearing of the available information regarding ornithine carbamoyltransferase isoenzymes on the evolution of the ancestral E. coli chromosome is reconsidered.
Effect of netropsin on the derepression of enzymes during growth and sporulation of Bacillus subtilis
Authors: Keilman G R , Brutis K , Tanimoto B , Doi R H
Published: January 2020

Netropsin, a polypeptide antibiotic which binds specifically to adenylate-thymidylate-rich regions of deoxyribonucleic acid, inhibitis sporulation at about stage II, but does not inhibit growth of Bacillys subtilis. An analysis of the sporulation-associated enzymes aconitase, alkaline phosphatase, and glucose dehydrogenase revealed that their rates of expression were not affected by the presence of the antibiotic. The derepression of histidase, a vegetatively induced enzyme was stimulated by netropsin. Oxygen utilization by the cells during sporulation was not effected nor was spore germination prevented by the drug. Netropsin, however, did prevent the formation of dipicolinic acid. These and earlier results suggest that netropsin may be affecting the transcription of only select sporulation genes that are particularly rich in adenylate-thymidylate base pairs.
Transport of vitamin B12 in Escherichia coli: energy dependence
Authors: Bradbeer C , Woodrow M L
Published: January 2020

This paper presents some evidence that the osmotic shock-sensitive, energy-dependent transfer of vitamin B12 from outer membrane receptor sites into the interior of cells of Escherichia coli requires an energized inner membrane, without obligatory intermediation of adenosine 5'-triphosphate (ATP). The experiments measured the effects of glucose, D-lactate, anaerobiosis, arsenate, cyanide, and 2,4-dinitrophenol upon the rates of B12 transport by starved cells of E. coli KBT001, which possesses a functional Ca2+, Mg2+-stimulated adenosine triphosphatase (Ca,MgATPase), and of E. coli AN120, which lacks this enzyme. Both strains were able to utilize glucose and D-lactate aerobically to potentiate B12 transport, indicating that the Ca,MgATPase was not essential for this process. When respiratory electron transport was blocked, either by cyanide or by anaerobic conditions, and the primary source of energy for the cells was presumably ATP from glucose fermentation, the rate of B12 transport was much reduced in E. coli AN120 but not in E.coli KBT001. These results support the view that the CaMgATPase can play a role in B12 transport but only when the energy for this process must be derived from ATP. The results of experiments with arsenate also supported the conclusion that the generation of phosphate bond energy was not absolutely required for B12 transport.
Stable, inducible thermoacidophilic alpha-amylase from Bacillus acidocaldarius
Authors: Buonocore V , Caporale C , De Rosa M , Gambacorta A
Published: January 2020

Bacillus acidocaldarius Agnano 101 produces an inducible thermoacidophilic alpha-amylase. The enzyme production occurs during the stationary phase of growth in the presence of compounds with alpha-1,4-glucosidic linkages. The enzymatic activity is both present in the culture medium and associated with the cells; the enzymes purified from both sources show identical molecular and catalytic properties. The purified amylase has a single polypeptide chain of molecular weight 68,000 and behaves like an alpha-amylase with affinity constants for starch and related substances of 0.8 to 0.9 mg/ml. The pH and temperature optima for activity are 3.5 and 75degreesC, respectively. The amylase is stable at acidic pH (below 4.5). Its thermal stability is strictly dependent upon protein concentration; the half-life at 60degreesC of the amylase in a 70-mug/ml solution is about 5 days.
Carbon and ammonia metabolism of Spirillum lipoferum
Authors: Okon Y , Albrecht S L , Burris R H
Published: January 2020

Intact cells and extracts from Spirillum lipoferum rapidly oxidized malate, succinate, lactate, and pyruvate. Glucose, galactose, fructose, acetate, and citrate did not increase the rate of O2 uptake by cells above the endogenous rate. Cells grown on NH+/4 oxidized the various substrates at about the same rate as did cells grown on N2. Added oxidized nicotinamide adenine dinucleotide generally enhanced O2 uptake by extracts supplied organic acids, whereas oxidized nicotinamide adenine dinucleotide phosphate had little effect. Nitrogenase synthesis repressed by growth of cells in the presence of NH+/4 was derepressed by methionine sulfoximine or methionine sulfone. The total glutamine synthetase activity from N2-grown cells was about eight times that from NH+/4-grown S. lipoferum; the response of glutamate dehydrogenase was the opposite. The total glutamate synthetase activity from N2-grown S. lipoferum was 1.4 to 2.6 times that from NH+/4-grown cells. The levels of poly-beta-hydroxybutyrate and beta-hydroxybutyrate dehydrogenase were elevated in cells grown on N2 as compared with those grown on NH+/4. Cell-free extracts capable of reducing C2H2 have been prepared; both Mg2+ and Mn2+ are required for good activity.
Photosystem II regulation of macromolecule synthesis in the blue-green alga Aphanocapsa 6714
Authors: Pelroy R A , Kirk M R , Bassham J A
Published: January 2020

Polymers synthesized by heterotrophically growing (glucose as carbon source) cultures of Aphanocapsa 6714 were compared with polymers synthesized in photosynthetically grown cultures. Loss of photosystem II by dark incubation, or inhibition of light-grown cells with the photosystem II-specific inhibitor dichlorophenylmethylurea, caused an 80 to 90% reduction in the rate of lipid and total ribonucleic acid synthesis, and more than a 90% reduction in the rate of protein synthesis. In contrast, glycogen synthesis was reduced only about 50% in dark cells and less than 30% in dichlorphenylmethylurea-inhibited cells. After longer heterotrophic growth, glycogen became the major component, whereas in photosynthetically grown cultures protein was the major constituent. 14C (from 14CO2 and/or [14C]glucose) assimilated into protein by heterotrophically grown cells was found in amino acids in nearly the same proportions as in photosynthetically grown cells. Thus, routes of biosynthesis available to autotropic cells were also available to heterotrophic cultures, but the supply of carbon precursors to those pathways was greatly reduced. The limited biosynthesis in heterotrophic cells was not due to a limitation for cellular energy. The adenylates were maintained at nearly the same concentrations (and hence the energy charge also) as in photosynthetic cells. The concentration of reduced nicotinamide adenine dinucleotide phosphate was higher in heterotrophic (dark) cells than in photosynthetic cells. From rates of CO2 fixation and/or glycogen biosynthesis it was determined that stationary-phase cells expended approximately 835, 165, and less than 42 nmol of adenosine 5'-triphosphate per mg (dry weight) of algae per 30 min during photosynthetic, photoheterotrophic, and chemoheterotrophic metabolism, respectively. Analysis of the soluble metabolite pools in dark heterotrophic cultures by double-labeling experiments revealed rapid equilibration of 14C through the monophosphate pools, but much slower movement of label into the diphosphate pools of fructose-1,6-diphosphate and sedoheptulose-1,7-diphosphate. Carbon did flow into 3-phosphoglycerate in the dark; however, the initial rate was low and the concentration of this metabolite soon fell to an undetectable level. In photosynthetic cells, 14C quickly equilibrated throughout all the intermediates of the reductive pentose cycle, in particular, into 3-phosphoglycerate. Analysis of glucose-6-phosphate dehydrogenase in cell extracts showed that the enzyme was very sensitive to product inhibition by reduced nicotinamide adenine dinucleotide.
Effect of polymyxin on the outer membrane of Salmonella typhimurium: freeze-fracture studies
Authors: Lounatmaa K , Nanninga N
Published: January 2020

Polymyxin-caused projections on the cell surface of Salmonella typhimurium were seen as depressions in the outer concave fracture face and as protrusions in the outer convex fracture face, indicating participation of both leaflets of the outer membrane in these projections.
Homoazasterol-mediated inhibition of yeast sterol biosynthesis
Authors: Bailey R B , Hays P R , Parks L W
Published: January 2020

A naturally occurring azasterol has been shown to inhibit sterol transmethylation in both in vitro and in vivo in the yeast Saccharomyces cerevisiae. The inhibition was competitive, with a calculated dissociation constant of 43 muM. The compound prevented the accumulation of ergosterol in aerobically adapting cells. Cultures forced to gain energy by respiration were found to be much more sensitive to growth inhibition by the azasterol than those cells fermenting glucose. The growth inhibition is reversible at low concentrations of the azasterol.
Evidence for a negative membrane potential and for movement of C1- against its electrochemical gradient in the ascomycete Neocosmospora vasinfecta
Authors: Miller A G , Budd K
Published: January 2020

The iodides of three lipid-soluble cations (dibenzyldimethylammonium; tribenzylmethylammonium, TBMA+; ethyldimethylbenzylammonium) were synthesized by the reaction of 14C-labeled methyl or 14C-labeled ethyl iodide with the appropriate secondary of tertiary amine and used in an attempt to measure the transmembrane electrical potential difference in Neocosmospora. Only mycelium containing high levels of Na+ accumulated measureable amounts of these cations and only above pH 6. Uptake was reduced in the presence of exogenous K+, Na+, Mg2+, or tris(hydroxymethyl)aminomethane. The velocity of TBMA+ uptake was proportional to its concentration between 46 and 427 muM. Neither the rate nor the extent of TBMB+ uptake was greatly affected by the presence of a fivefold excess of either dibenzyldimethylammonium or ethyldimethylbenzylammonium, even though these cations were themselves accumulated. The uncoupler m-chlorophenylhydrazone induced loss of previously accumulated TBMA+ from the mycelium. Anaerobiosis and cold (5 degrees C) temperature both inhibited TBMA+ uptake but did not induce the loss of previously accumulated TBMA+. The uptake of lipophilic cations by Na+-rich mycelium indicated a minimum transmembrane electrical potential of -60 to -70 mV (inside negative). Net uptake of these cations appeared to be strongly influenced by the availability of endogenous exchangeable cations and by the presence of other exogenous cations, as well as by the membrane potential. Despite these limitations, transport of C1- by Na+-rich mycelium appeared to take place against the electrochemical gradient for C1-.
Fosfomycin resistance: selection method for internal and extended deletions of the phosphoenolpyruvate:sugar phosphotransferase genes of Salmonella typhimurium
Authors: Cordaro J C , Melton T , Stratis J P , Atagün M , Gladding C , Hartman P E , Roseman S
Published: January 2020

Selection for resistance to the antibiotic fosfomycin (FOS; L-cis 1,2-epoxypropylphosphonic acid, a structural analogue of phosphoenolpyruvate) was used to isolate mutants carrying internal and extended deletions of varying lengths within the ptsHI operon of Salmonella typhimurium. Strains carrying "tight" ptsI point mutations and all mutants in which some or all of the ptsI gene was deleted were FOS resistant. In contrast, strains carrying ptsH point mutations were sensitive to FOS. Resistance to FOS appeared to result indirectly from catabolite repression of an FOS transport system, probably the sn-glycerol-3-phosphate transport system. Resistant ptsI mutants became sensitive to FOS when grown on D-glucose-6-phosphate, which induces an alternate transport system for FOS, or when grown in the presence of cyclic adenosine 3',5'-monophosphate. A detailed fine-structure map of the pts gene region is presented.
Octopine and nopaline metabolism in Agrobacterium tumefaciens and crown gall tumor cells: role of plasmid genes
Authors: Montoya A L , Chilton M D , Gordon M P , Sciaky D , Nester E W
Published: January 2020

Crown gall tumors produced octopine or nopaline or neither compound, depending on the bacterial strain that incited the tumor. The genes specifying production of octopine or nopaline by the tumor were transferred to recipient bacterial strains when the large plasmid associated with virulence was transferred by either conjugation or deoxyribonucleic acid-mediated transformation. Our results, which confirm the work of others (Bomhoff et al., 1976; Goldman et al., 1968; Petit et al., 1970), indicate that, in general, the strains that utilize octopine induce tumors that synthesize octopine, and those that utilize nopaline induce tumors that synthesize nopaline. However, there were several notable exceptions. One class utilized both octopine and nopaline, but the tumors induced by these strains produced only nopaline. Another class utilized nopaline, but their tumors synthesized neither nopaline nor octopine. Mutants were isolated from a number of either octopine- or nopaline-utilizing strains that no longer could utilize the relevant guanido amino acid. These strains, which were mutant in the gene specifying octopine or nopaline oxidase, still retained the permease for these amino acids as well as virulence. Tumors induced by these mutants still synthesized approximately the same levels of octopine and nopaline as tumors induced by their parents. These results suggest that the plasmid gene that determines production of octopine or nopaline by the tumor is distinct from the plasmid gene that determines their catabolism by the bacteria.
Tetrahydrofolate-dependent biosynthesis of ribothymidine in transfer ribonucleic acids of Gram-positive bacteria
Authors: Schmidt W , Arnold H H , Kersten H
Published: January 2020

Trimethoprim, an inhibitor that prevents tetrahydrofolate-dependent transmethylation reactions inbacteria, was used in a comparative study to discriminate between two possible biosynthetic pathways, either the S-adenosylmethionine or the tetrahydrofolate-dependent formation of ribothymidine (rT) in transfer ribonucleic acids (tRNA's) of several strains of gram-positive and gram-negative microorganisms. rT-deficient tRNA's accumulate in trimethoprim-treated gram-positive Streptococcus faecium, Staphylococcus aureus, Corynebacterium bovis, Arthrobacter albidus, and all examined Bacillaceae, except Bacillus stearothermophilus. The rT-deficient rT-deficient tRNA's accept the methyl moiety from S-adenosylmethionine in vitro, with extracts from Escherichia coli (wild type) as a source of methylating enzymes; 90% of the incorporated methyl groups are present in rT. Trimethoprim does not inhibit the biosynthesis of rT in tRNA of gram-negative Enterobacteriaceae, Rhizobium lupini, and Pseudomonadaceae, suggesting that the rT-specific tRNA methyltransferases of these gram-negative strains use S-adenosylmethionine as coenzyme.
Penicillinase-releasing protease of Bacillus licheniformis: purification and general properties
Authors: Aiyappa P S , Traficante L J , Lampen J O
Published: January 2020

The membrane penicillinase of Bacillus licheniformis 749/C is a phospholipoprotein which differs from the exoenzyme in that it has an additional sequence of 24 amino acid residues and a phosphatidylserine at the NH2 terminus. In exponential-phase cultures, the conversion of membrane penicillinase to exoenzyme occurs at neutral and alkaline pH. An enzyme that will cleave the membrane penicillinase to yield the exoenzyme is present (in small amounts) in exponential-phase cells and is released during their conversion to protoplasts. The enzyme is found in the filtrate of a stationary-phase culture of the uninduced penicillinase-inducible strain 749 and has been purified to apparent homogeneity from this source. The protease has an approximate molecular weight of 21,500 and requires Ca2+ ions for stabilization. It has a pH optimum of 7.0 to 9.5 for hydrolysis of casein and for the cleavage of membrane penicillinase. Both activities are inhibited by diisopropylfluorophosphate; hence, the enzyme is a serine protease. This enzyme may be entirely responsible for the formation of exopenicillinase by this organism, since the other neutral and alkaline proteases of strain 749 have little, if any, activity in releasing exopenicillinase. The enzyme has been termed penicillinase-releasing protease.
Carboxylation of phosphoenolpyruvate by extracts of Neisseria gonorrhoeae
Authors: Cox D L , Baugh C L
Published: January 2020

The enzymatic carboxylation of phosphoenolpyruvate by cell-free extracts of Neisseria gonorrhoeae was examined and determined to be similar to the reaction catalyzed by phosphoenolpyruvate carboxylase (PEPC). This was shown by the irreversibility of the reaction and nucleotide independency. The enzyme was found to have some characteristics different from the other bacterial PEPCs reported. The enzyme showed catalytic activity in the presence of cobalt ions as well as magnesium and manganese ions, was not inhibited by succinate in fresh extracts, and displayed a low Michaelis constant for bicarbonate (0.27 mM), as compared with other PEPCs. The significance of this low Michaelis constant is discussed with respect to the growth of the organism and the importance of this enzyme to protein and nucleic acid synthesis.
Mitochondrial biogenesis during fungal spore germination: respiratory cytochromes of dormant and germinating spores of Botryodiplodia
Authors: Brambl R , Josephson M
Published: January 2020

The mitochondrial respiratory cytochrome contents of dormant and germinating conidia of Botryodiplodia theobromae were examined. Oxidized versus reduced difference spectra at 77 degrees K of whole mitochondria from physiologically mature germinated spores showed a typical a-band pattern for cytochromes c, b, and a, with absorption maxima at 549, 554 + 559, and 604 nm, respectively, whereas the difference spectrum of the counterpart mitochondrial fraction from dormant spores showed no cytochrome a bands. However, a fraction prepared from dormant spore mitochondria by detergent extraction and (NH4)2SO4 fractionation contained readily detectable quantities of cytochromes c and b (as shown by the a and Soret absorption bands), but it did not contain the a or Soret bands of cytochrome a observed in a counterpart preparation from germinated spores. The pyridine hemochromogen preparation from the dormant spore mitochondria contained no material that is spectroscopically characteristic of a-type heme and protoheme. These results suggest that cytochrome a is not present as a functional molecule in dormant spores. The first spectroscopically detectable cytochromes were observed in whole mitochondria at 210 min of spore germination, and the amount of each of the cytochromes increased with cell growth. A precursor of the heme porphyrin, delta-[4-14C]aminolevulinic acid, was first incorporated (at accelerating rates) into acid-insoluble spore material at 180 min of germination, which appears to be the approximate time of organization of new mitochondria in these spores.
Growth pattern and cell division in Neisseria gonorrhoeae
Authors: Westling-Häggström B , Elmros T , Normark S , Winblad B
Published: January 2020

The gram-negative coccus Neisseria gonorrhoeae was found to grow regularly in at least two dimensions. Growth proceeded at a linear rate sequentially in each dimension. Growth in the second dimension (former width) was initiated slightly before the pole-division plane distance equalled the cell width. Penicillin treatment localized presumptive growth zones to the existing septum region. It was suggested that new growth zones were always formed perpendicular to the longitudinal axis created in the incipient daughter cells of a dividing coccus. Neither penicillin nor nalidixic acid induced filaments of N. gonorrhoeae. Such structures could nevertheless be formed in the rod-shaped species Neisseria elongata. N. gonorrhoeae divides by septation; however, complete septal structures with separated cytoplasms were rather infrequent. It is proposed that N. gonorrhoeae be regarded as a short rod which always extends parallel to the actual longitudinal axis and which never undergoes a rod-sphere-rod transition.
Mitomycin C-induced expression of trpA of Salmonella typhimurium inserted into the plasmid ColE1
Authors: Selker E , Brown K , Yanofsky C
Published: January 2020

EcoRI endonuclease digestion of the deoxyribonucleic acid of a phi80 transducing phage carrying the entire tryptophan (trp) operon of Salmonella typhimurium (phi80 S.t.trpE-A) yielded a 4.3 X 10(6)-dalton fragment containing intact trpE, trpD, and trpC and a 3.35 X 10(6)-dalton fragment containing intact trpA. The trpA fragment inserted into EcoRI-cleaved plasmids ColE1 and CR1 was expressed regardless of its orientation of insertion. Mitomycin C, a compound that induces colicin E1 production in ColE1-containing bacteria, stimulated tryptophan synthetase alpha production in cells containing ColE1-TRPA plasmids with the trpA fragment inserted in one orientation but not the other. We conclude that in the inducible plasmids trpA can be expressed from the colicin E1 promoter.
Bacillus subtilis ribonucleic acid polymerase mutants conditionally temperature sensitive at various stages of sporulation
Authors: Sumida-Yasumoto C , Doi R H
Published: January 2020

Rifampin-resistant mutants of Bacillus subtilis that are conditionally temperature sensitive during sporulation have been isolated and characterized. The mutants can grow at the same rate as the wild type at the nonpermissive temperature but cannot sporulate. Depending on the mutation, they are blocked at either stage 0 to I, II, II to III, or IV of sporulation. The mutants showed an altered pattern of RNA synthesis after the stage at which they were blocked. The effect of rifampin on the activity of enzymes from mutant vegetative cells and sporulating cells was significantly different, suggesting that the RNA polymerase from sporulating cells was different from the RNA polymerase of vegetative cells. These results suggest that the conformation of the RNA polymerase core plays an important role in determining correct transcription during sporulation.
Biochemical parameters of glutamine synthetase from Klebsiella aerogenes
Authors: Bender R A , Janssen K A , Resnick A D , Blumenberg M , Foor F , Magasanik B
Published: January 2020

The glutamine synthetase (GS) from Klebsiella aerogenes is similar to that from Escherichia coli in several respects: (i) it is repressed by high levels of ammonia in the growth medium; (ii) its biosynthetic activity is greatly reduced by adenylylation; and (iii) adenylylation lowers the pH optimum and alters the response of the enzymes to various inhibitors in the gamma-glutamyl transferase (gammaGT) assay. There are, however, several important differences: (i) the isoactivity point for the adenylylated and non-adenylylated forms in the gammaGT assay occurs at pH 7.55 in K. aerogenes and at pH 7.15 in E. coli; (ii) the non-adenylylated form of the GS from K. aerogenes is stimulated by 60 mM MgCl2 in the gammaGT assay at pH 7.15. A biosynthetic reaction assay that correlates well with number of non-adenylylated enzyme subunits, as determined by the method of Mg2+ inhibition of the gammaGT assay, is described. Finally, we have found that it is necessary to use special methods to harvest growing cells to prevent changes in the adenylylation state of GS from occurring during harvesting.
Establishment of exponential growth after a nutritional shift-up in Escherichia coli B/r: accumulation of deoxyribonucleic acid, ribonucleic acid, and protein
Authors: Brunschede H , Dove T L , Bremer H
Published: January 2020

The accumulation of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein was followed in cultures of Escherichia coli B/r during exponential growth in different media and for 2 h after a nutritional shift-up from succinate minimal medium (growth rate [mu1] = 0.67 doublings per h) to glucose plus amino acids medium (mu2 = 3.14 doublings per h). During postshift growth of the culture, the amounts of RNA (R), DNA (D), and protein (P) increased such that the ratios of the increments (delta R/delta P; delta D/delta P) were constants (k1, k2). This implies that the rates of accumulation of nuclei1:k2:1. These constants change from their preshift value to their final postshift value (i.e., k1 and k2) within a few minutes after the shift. k1 is a function of the activity of ribosomes, whereas k2 is related to the initiation of rounds of DNA replication. These parameters and the observed change in the doubling time of RNA (= mu2/mu1) were used to derive kinetic equations that describe the accumulation of DNA, RNA, protein, and cell mass during the 2- to 3-h transition period after a shift-up. The calculated kinetics agree closely with the observed kinetics.
Macromolecular Composition of Spores from the Filamentous Cyanobacterium
Anabaena cylindrica
Authors: Simon Robert D.
Published: January 2020

Spores were isolated from the filamentous cyanobacterium
Anabaena cylindrica
, and their deoxyribonucleic acid, ribonucleic acid, and protein compositions were determined.
Influence of the stringent control system on the transcription of ribosomal ribonucleic acid and ribosomal protein genes in Escherichia coli
Authors: Dennis P P
Published: January 2020

The fraction of the total ribonucleic acid (RNA) synthesis rate that is messenger RNA (mRNA) for ribosomal protein (r-protein) and ribosomal RNA (rRNA) has been estimated in valS(Ts) rel+ stringent and valS(Ts) relA1 relaxed strains of Escherichia coli during a partial inhibition of valyl-transfer RNA aminoacylation. The partial inhibition was accomplished by shifting the strains from the permissive growth temperature of 29.5 degrees C to the semipermissive temperature of 35.5 degrees C. The RNA synthesized at the elevated temperature was pulse labeled with [3H]uracil. The fraction of the total incorpoarted 3H radioactivity in r-protein mRNA or in rRNA was estimated by specific hybridization to the transducing phages gammaspc1, which carries about 15 r-protein genes and lambdailv5, which carries an rRNA transcription unit. The results clearly demonstrate that the rel gene influences the fraction of the total RNA synthesis rate that is r protein mRNA and rRNA; in the rel+ strain they are significantly increased relative to control cultures. This indicates that the expression of the genes coding for the RNA and protein component of the ribosome are most likely regulated at the level of transcription. Furthermore, it appears that the distribution of functioning RNA polymerase between rRNA genes, r-protein genes, and other types of genes is influenced by the rel gene control system; presumably this influence is mediated through the unusual nucleotide guanosine tetraphosphate.
Characterization of autolysins from Mycobacterium smegmatis
Authors: Kilburn J O , Best G K
Published: January 2020

This study demonstrates, for the first time, the autolytic enzymes associated with mycobacterial cell walls. Based on the release of radioactivity and ninhydrin-reactive material from isolated cell walls, it was shown that maximum activity occurs during the late log phase of growth and at a buffer pH of about 8.0. Chemical analyses of autolytic digests of isolated cell walls indicated that at least three autolysins are active under the conditions used. These are N-glycolylmuramic acid-L-alanine amidase, an aminopeptidase that releases L-alanine, and an endopeptidase that solubilizes and L-alanyl-D-glutamic acid dippetide. No other endopeptidase, carboxypeptidase, or glycosidase activity was detected.