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F T Robb

Publications and source records attributed to F T Robb.

At least 37 records · Page 2Linked to original sources
PubMed1985

Purification and regulation of glutamine synthetase in a collagenolytic Vibrio alginolyticus strain.

Glutamine synthetase (EC 6.3.1.2) has been purified from a collagenolytic Vibrio alginolyticus strain. The apparent molecular weight of the glutamine synthetase subunit was approximately 62,000. This indicates a particle weight for the undissociated enzyme of 744,000, assuming the enzyme is the typical dodecamer. The glutamine synthetase enzyme had a sedimentation coefficient of 25.9 S and seems to be regulated by adenylylation and deadenylylation. The pH profiles assayed by the gamma-glutamyltransferase method were similar for NH4-shocked and unshocked cell extracts and isoactivity point was not obtained from these curves. The optimum pH for purified and crude cell extracts was 7.9. Cell-free glutamine synthetase was inhibited by some amino acids and AMP. The transferase activity of glutamine synthetase from mid-exponential phase cells varied greatly depending on the sources of nitrogen or carbon in the growth medium. Glutamine synthetase level was regulated by nitrogen catabolite repression by (NH4)2SO4 and glutamine, but cells grown in the presence of proline, leucine, isoleucine, tryptophan, histidine, glutamic acid, glycine and arginine had enhanced levels of transferase activity. Glutamine synthetase was not subject to glucose, sucrose, fructose, glycerol or maltose catabolite repression and these sugars had the opposite effect and markedly enhanced glutamine synthetase activity.

Ammonium Sulfate↗
PubMed1983

The amino acid sequence of D-ribose-binding protein from Escherichia coli K12.

The amino acid sequence of the D-ribose-binding protein from Escherichia coli K12 was determined from the DNA sequence of the gene. Protein sequence analyses covering 80% of the protein were consistent with the sequence deduced from the DNA. The mature binding protein has 271 amino acid residues and shows substantial homology to D-galactose-binding protein. A signal peptide sequence of 23 or 25 residues was also deduced from the DNA sequence. It shows the characteristic features of prokaryotic signal peptides.

Amino Acid Sequence↗
PubMed1982

Regulation of hut enzymes and intracellular protease activities in Vibrio alginolyticus hut mutants.

The production of alkaline protease, collagenase and histidine utilization (Hut) enzymes by Vibrio alginolyticus wild-type, hutH1 and hutU1 strains was investigated. Alkaline protease synthesis was stimulated by histidine and urocanic acid in the wild-type and hutU1 strains. The hutH1 mutant alkaline protease production was stimulated by urocanic acid and not by histidine. The Hut enzymes in the wild-type strain were coordinately induced by histidine. Urocanase and formimino-hydrolase were induced by histidine in the hutH1 mutant which lacked histidase and was not able to convert histidine to urocanic acid. Collagenase production in peptone medium was inhibited in the hut mutants. It is concluded that in V. alginolyticus urocanic acid regulates alkaline protease synthesis but that the Hut enzymes are induced by histidine. The involvement of the Hut genetic system in the regulation of alkaline protease and collagenase synthesis is discussed.

Bacterial Proteins↗
PubMed1981

Regulation of exoprotease production by temperature and oxygen in Vibrio alginolyticus.

The production of an extracellular collagenase and alkaline protease by Vibrio alginolyticus during stationary phase was inhibited by a temperature shift from 30 to 37 degrees C and by a lack of oxygen. The stability of the exoproteases was unaffected by incubation at 37 degrees C and aeration. The optimum growth temperature for the V. alginolyticus strain was 33.5 degrees C and there was no difference in the growth rate at 30 and 37 degrees C. Aeration enhanced the rate of growth of exponential phase cells. Temperature and oxygen did not affect the growth of stationary phase cells when the exoproteases were being produced. Macromolecular synthesis in stationary phase cells was not affected by temperature. There was no rapid release of the exoproteases after temperature shift down and chloramphenicol inhibited the production of the enzymes when added at time of temperature shift down from 37 to 30 degrees C. The regulation of exoprotease production by temperature and oxygen was specific and has implications regarding the ecology of V. alginolyticus. Cerulenin, quinacrine and O-phenanthroline inhibited the production of the exoproteases.

Cerulenin↗
PubMed1981

Regulation of extracellular alkaline protease activity by histidine in a collagenolytic Vibrio alginolyticus strain.

Vibrio alginolyticus synthesized an inducible extracellular collagenase in a peptone medium during the stationary growth phase. These cultures also possessed extracellular alkaline serine protease activity. The alkaline protease activity did not require a specific inducer and it was produced in tryptone or minimal media. The collagenase was not produced in either the tryptone or minimal media. The alkaline protease activity was sensitive to catabolite repression by a number of carbon sources, including glucose, and by amino acids and ammonium ions. Cyclic AMP, dibutyryl cyclic AMP and cyclic GMP did not relieve catabolite repression. Histidine and urocanic acid stimulated the production of alkaline protease activity in tryptone and minimal media. Other compounds associated with the histidine utilization (hut) pathway did not increase alkaline protease activity. Histidine reversed the repression of alkaline protease activity by glucose of (NH4)2SO4 in minimal medium. Histidine and the compounds associated with the hut pathway inhibited collagenase production.

Amino Acids↗
PubMed1981

Inhibition of ribonucleic acid polymerase by a bacteriocin from Bacteroides fragilis.

The Bacteroides fragilis bacteriocin which inhibits ribonucleic acid (RNA) polymerase activity had a narrow activity spectrum in vivo and only inhibited the growth of certain B. fragilis strains. In vitro the bacteriocin was not specific and inhibited RNA polymerases from widely diverse bacterial genera. RNA polymerases from rifampin-resistant strains of Bacteroides thetaiotaomicron and Clostridium acetobutylicum were resistant to the bacteriocin in vitro. Purified bacteriocin bound to partially purified RNA polymerase, and both proteins were cosedimented in a glycerol gradient. In the RNA polymerase reaction, the bacteriocin acted as a competitive inhibitor for adenosine, cytidine, and uridine 5'-triphosphates and as a noncompetitive inhibitor for guanosine 5'-triphosphate. The bacteriocin did not inhibit RNA polymerase from chicken embryos.

Bacteriocins↗
PubMed1980

Reconstitution of binding protein dependent ribose transport in spheroplasts derived from a binding protein negative Escherichia coli K12 mutant and from Salmonella typhimurium.

Highly purified ribose-binding protein from Escherichia coli has been used to reconstitute binding-protein-dependent ribose transport in spheroplasts derived from a binding-protein-deficient mutant of E coli K12, and in spheroplasts derived from Salmonella typhimurium. The cross-species reconstitution was nearly as efficient as the reconstitution of the E coli strain from which the binding protein was derived. Antibody raised against the ribose binding protein completely prevented reconstitution, whereas it had no effect on whole cells. The reconstitution procedure has been improved by generating spheroplasts from cells grown in a rich medium and by reducing the background uptake in spheroplasts through a special washing procedure. Rapid purification of ribose binding protein by high pressure liquid chromatography is also described.

Bacterial Proteins↗
PubMed1980

Physiological and morphological characteristics of stationary phase vibrio cells able to support phase growth.

Growth of phase alpha 3a on stationary phase Vibrio cultures requires micro-aerophilic conditions and is inhibited by aeration. Since pre-conditioning of the bacteria by allowing them to stand for 24 h after shaking for 3 d is an important aspect of the stationary phase phage growth system, various physiological and morphological characteristics of the stationary phase cells during the transition from shaking to standing were investigated. Shaken stationary phase cells were less viable and more sensitive to ultraviolet irradiation and heat than standing stationary phase cells. During pre-conditioning the small, non-flagellated cells present in shaken stationary phase cultures underwent morphological changes and became large, flagellated rods which resembled exponential phase cells. The transition of stationary phase cells from shaking to standing was associated with a marked increase in total RNA synthesis but a rapid and large decrease in total protein synthesis. Intracellular concentrations of ATP in shaken stationary phase cells were 53% lower than those in standing stationary phase cells. Studies on leucine uptake indicated that its transport was inhibited by isoleucine and that the major part (90%) of the total leucine uptake was due to a shared system for uptake of both amino acids. Shaken stationary phase cells transported less leucine than standing stationary phase cells. Inhibition of phage growth in aerated stationary phase cultures was not due to the prevention of phase absorption by shaking. It is suggested that the observed differences between shaken and standing stationary phase cells could be due to aeration affecting the template specificity of the Vibrio RNA polymerase.

Adenosine Triphosphate↗
PubMed1980

Rifampin and bacteriocin resistance in Bacteroides fragilis.

A low-molecular-weight bacteriocin produced by a Bacteroides fragilis strain inhibited ribonucleic acid polymerase activity in crude extracts of a susceptible B. fragilis indicator strain. A total of 10 rifampin-resistant mutants of the indicator strain were isolated. Nine of the rifampin-resistant mutants were resistant to the bacteriocin, and the other mutant was hypersusceptible. The rifampin- and bacteriocin-resistant mutants all adsorbed approximately the same amount of the bacteriocin as the indicator strain. Two of these rifampin- and bacteriocin-resistant mutants were investigated further, and the polymerase activity in crude extracts of the two mutants was not affected by either rifampin or the bacteriocin. The in vitro ribonucleic acid polymerase activity of the hypersusceptible strain was more susceptible to the bacteriocin than the parent indicator strain was. The bacteriocin-producing strain was susceptible to rifampin but was resistant to its own bacteriocin in vivo. The in vitro ribonucleic acid polymerase activity of the producer strain was only slightly affected by 64 arbitrary units of the bacteriocin. Increasing concentrations of the bacteriocin inhibited ribonucleic acid polymerase extracts of the producer strain.

Bacteriocins↗
PubMed1980

Peptone induction and rifampin-insensitive collagenase production by Vibrio alginolyticus.

Vibrio alginolyticus produces an extracellular collagenase which requires specific induction by collagen or its high-molecular-weight fragments. Peptone also induces collagenase during the late exponential and early stationary growth phases. The peptone inducers have been shown to have a broad molecular weight range between 1,000 and 60,000. The peptone inducers supported slow growth of V. alginolyticus when supplied as the sole nitrogen source in minimal medium. Digestion of the peptone inducers with purified V. alginolyticus collagenase resulted in a decrease in their inducing ability, whereas digestion with trypsin or alpha-chymotrypsin did not. This indicated that induction by the inducers required the presence of collagenase-sensitive bonds. Prolonged digestion of the inducers with collagenase did not completely eliminate the inducing ability of the inducers. The peptone inducers acted as inhibitors of collagenase. A minimal medium induction system has been developed which involves resuspending cells at high density in a medium containing succinate, (NH(4))(2)SO(4), KH(2)PO(4), and the peptone inducer. Cells grown in minimal medium induce earlier than cells grown on peptone, Casamino Acids, or tryptone. Collagenase production was shown to occur for 30 to 60 min in the presence of rifampin at levels which completely inhibit the incorporation of [(3)H]uracil into trichloroacetic acid-precipitable material. Chloramphenicol completely and immediately abolished collagenase production, which together with labeling studies has confirmed that collagenase production involves de novo synthesis of the enzyme. Both glucose and Casamino Acids repressed collagenase production, although synthesis of the enzyme continued for 30 to 60 min after their addition. The repression of collagenase production by glucose and Casamino Acids was more severe than the inhibition of enzyme formation due to addition of rifampin.

Amino Acids↗
PubMed1979

Characterization and mode of action of a bacteriocin produced by a Bacteroides fragilis strain.

A Bacteroides fragilis strain produces a low-molecular-weight (13,500 to 18,700), proteinaceous bacteriocin during the stationary growth phase. The extracellular bacteriocin is not inducible by ultraviolet light or mitomycin C and is stable between pH 7.5 and 8.2. The majority of the bacteriocin is thermolabile, but a small proportion (3%) of the bacteriocin is stable after autoclaving at 121 degrees C for 15 min. Killing of sensitive bacteroides cells follows single-hit kinetics, and the interaction of a single molecule of bacteriocin with a target cell occurs in two stages. The killing of susceptible cells is affected by temperature and the growth state of the susceptible cells. The bacteriocin is unusual in that the primary event in its mode of action is the inhibition of RNA synthesis. The bacteriocin inhibits RNA synthesis immediately but has no effect on DNA synthesis or intracellular ATP levels. Protein synthesis is inhibited after a delay of 20 min, presumably as a result of the initial inhibition of RNA synthesis.

Adenosine Triphosphate↗
PubMed1979

Bacteriocin production by Clostridium acetobutylicum in an industrial fermentation process.

High titers of a noninducible bacteriocin were produced by Clostridium acetobutylicum in a molasses fermentation medium used for the industrial production of solvents. Release of the bacteriocin towards the end of the exponential growth phase was accompanied by lysis of the culture and inhibition of the production of solvents. The producer cells were sensitive to the bacteriocin, which only affected other C. acetobutylicum strains and a Clostridium felsineum strain. The thermolabile bacteriocin was not inactivated by protease enzymes and had no optimum stability between pH 4 and 5. The sedimentation coefficient of the bacteriocin was 6S.

Bacteriocins↗
PubMed1978

Phage growth characteristics on stationary phase Achromobacter cells.

The growth characteristics of alpha3a bacteriophage on stationary phase Achromobacter strain 14 are described. Phage alpha3a growth on stationary phase cells is characterized by a long and variable latent period of 6 to 9 h and an increased burst size of 710 p.f.u./cell as compared with 153 p.f.u./cell in exponential wild type cells. During the latent period the infected cells are very sensitive to changes in growth conditions and in particular, dilution. Pre-conditioning of the bacterial cells by allowing them to stand for 24 h after shaking for 3 days is an important aspect of the stationary phase phage growth system. Cells which have been allowed to stand retain the ability to be infected and to support phage growth for at least 16 days. Shaking cultures gradually lose the ability to support phage growth but the phage can persist in the host cell for 10 days until removal from shaking when the lytic cycle can proceed after allowing the cultures to stand.

Adsorption↗
PubMed1977

Rifampicin-resistant mutant supporting bacteriophage growth on stationary phase Achromobacter cells.

A rifampicin-resistant Achromobacter mutant with an altered RNA polymerase was isolated. The mutant supports phage alpha3a growth in both log and stationary phase cells. Phage growth on stationary phase cells is sensitive to aeration and growth only occurs at oxygen concentrations of less than 5-2 p.p.m. The rifampicin-resistant mutant is similar to the spontaneous mutant strain 14 reported by Woods (1976) in that both mutants support stationary-phase phage growth under micro-aerophilic conditions. The isolation of the rifampicin-resistant mutant with an altered RNA polymerase suggests that the phenomenon of stationary phase phage growth could be due to a change in the template specificity of the Achromobacter RNA polymerase. Plaque morphology mutants which grow on log and/or stationary phase cells of the Achromobacter wild type, strain 14 and rifampicin-resistant strains are also described.

Alcaligenes↗