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J G Coote

Publications and source records attributed to J G Coote.

52 records · Page 3Linked to original sources
PubMed1985

Adenylate cyclase activity during phenotypic variation of Bordetella pertussis.

During MgSO4-induced modulation of Bordetella pertussis, adenylate cyclase activity, histamine-sensitizing activity (HSA) and the major cell-envelope polypeptides with Mr 28000 and 30000 (X polypeptides) were lost synchronously at a rate which could be accounted for by a simple growth-dilution effect. MgSO4 and other compounds which induced the above phenotypic change caused little inhibition of adenylate cyclase activity. Nicotinic acid was the sole exception and at 4.1 mM-caused 60% inhibition of activity. Lysates of modulated cells, mixed with lysates of unmodulated cells, had no effect on either adenylate cyclase activity or HSA. Protein synthesis was a prerequisite for MgSO4-induced modulation and also for the reversal of this process. Exogenous cAMP and dibutyryl cAMP (5 mM) had no counteracting effect on MgSO4- or nicotinic acid-induced modulation. The concentration of MgSO4 required to induce loss of the X polypeptides (10 to 11 mM) was not altered by promoting adenylate cyclase activity by including an activator in the growth medium. In one culture containing 10 mM-MgSO4 and activator, partial loss of the X polypeptides occurred and yet the extracellular cAMP concentration was twice that of cultures without activator and where full expression of the X polypeptides occurred. [3H]cAMP-binding activity was detected in cell extracts of several strains of B. pertussis, but antiserum against purified Escherichia coli catabolite repressor protein gave no reaction with B. pertussis cell extracts. Respiration rates with amino acids were similar for modulated and unmodulated variants and an avirulent strain of B. pertussis. These results are discussed in relation to a possible causal role for adenylate cyclase in modulation of B. pertussis.

Adenylyl Cyclases↗
PubMed1983

Density gradient analysis of DNA replicated during Bacillus subtilis sporulation.

Density gradient centrifugation was used to monitor DNA replication during sporulation of a 5-bromo-2'-deoxyuridine-tolerant, thymidine-requiring strain of Bacillus subtilis. DNA of heavy, intermediate, and light density was found in cells induced to sporulate in the presence of bromodeoxyuridine, but only intermediate DNA was detected in mature spores. Cells grown with bromodeoxyuridine until DNA was in the heavy form formed spores containing intermediate and light DNA when sporulated with thymidine alone.

Bacillus subtilis↗
PubMed1982

Sporulation competence in Physarum polycephalum CL and the requirement for DNA replication and mitosis.

The optimum conditions for sporulation and the requirements for mitosis and DNA replication during the onset of the process have been investigated in plasmodia of the CL strain of Physarum polycephalum. A 72 h period of starvation was necessary before a plasmodium became competent to sporulate on exposure to light. The plasmodium became irreversibly committed to sporulation 4 to 5 h after illumination. The commitment point was related to the time of illumination rather than the duration of starvation. Three periods of DNA synthesis were detected during the initial 24 h of starvation, but in an asporogenous derivative of the CL strain only the first two periods were detected. Inhibition of mitosis with nocodazole or of DNA synthesis with hydroxyurea prevented sporulation. Escape of plasmodia from hydroxyurea inhibition of sporulation coincided with the last detectable period of DNA synthesis, but escape from nocodazole inhibition of sporulation occurred 25 to 30 h later.

Antifungal Agents↗
PubMed1979

Glutamine synthetase and glutamate synthase activities during growth and sporulation in Bacillus subtilis.

Glutamine synthetase in Bacillus subtilis 168 was repressed to a greater extent by L-glutamine or L-arginine than by ammonia when each was used as sole nitrogen source. It was derepressed when either L-glutamate or nitrate was used as nitrogen source. Glutamate synthase was repressed by L-glutamate or L-arginine and, to a lesser extent, by L-glutamine but was derepressed during growth with ammonia or nitrate. Glutamine synthetase activity was unaltered during the onset of sporulation. Glutamate synthase activity, however, underwent a small and apparently transient increase in bacteria induced to sporulate by nitrogen limitation.

Bacillus subtilis↗
PubMed1979

Degradation of bacterial lipopolysaccharide by the slime mould Physarum polycephalum.

A strain of the acellular slime mould Physarum polycephalum degraded lipopolysaccharides (LPS) from a variety of bacteria. The anticomplementary (AC) activity of LPS was greatly reduced, as was the content of lauric, myristic, and palmitic acids, and the ability to sensitize erythrocytes to agglutination by antibody. These results indicate that Physarum has enzymes which reduce the lipid A moiety of LPS. In contrast, 2-keto-3-deoxy-D-manno-actanoic acid (KDO), immunodominant sugars, and beta-hydroxymyristic acid were scarcely affected. Both supernates and plasmodial extracts of Physarum had LPS-degradative activity and were able to attack both purified LPS and LPS in killed bacteria.

Biodegradation, Environmental↗
PubMed1975

Cytochemical studies on alkaline phosphatase production during sporulation in Bacillus subtilis.

During sporulation of Bacillus subtilis 168 there is an increase in activity of alkaline phosphatase in the presence of Pi. This enzyme was shown by cytochemical techniques to be associated with the cytoplasmic membrane of the mother cell and also with the membranes of the developing prespore. There is a strong correlation between an increasing number of electron-dense deposits due to phosphatase activity and the formation of the spore septum, i.e. stage II of sporulation. Cytochemical and biochemical evidence shows that cells well advanced in spore formation can be derepressed to produce the very much higher amounts of alkaline phosphatase characteristic of phosphate-starved vegetative cells.

Alkaline Phosphatase↗
PubMed1974

Comparative studies on induction of sporulation and synthesis of inducible enzymes in Bacillus subtilis.

An attempt was made to determine whether sporulation and inducible enzyme synthesis in Bacillus subtilis are controlled by the same mechanism of catabolite repression. By the use of a thymine-requiring strain, it has been shown that, whereas sporulation remained repressed unless chromosome replication proceeded to completion, the induction of the enzymes histidase, sucrase, and alpha-glucosidase proceeded quite normally in the absence of continued deoxyribonucleic acid synthesis. It is concluded that the mechanism for overcoming the repression of sporulation differs qualitatively from that involved in overcoming the repression of inducible enzyme synthesis. Attempts to isolate pleiotropic mutants that would provide additional support for this contention were unsuccessful. A pleiotropic mutant deficient in phosphoenolpyruvate-dependent phosphotransferase activity sporulated quite well, whereas a mutant presumed deficient in glutamate synthetase sporulated poorly under all conditions.

Alkaline Phosphatase↗
PubMed1973

The degradation of L-histidine, imidazolyl-L-lactate and imidazolylpropionate by Pseudomonas testosteroni.

1. Imidazol-5-ylpropionate and imidazol-5-yl-lactate are degraded by Pseudomonas testosteroni via inducible pathways. 2. Growth on either compound as the sole source of carbon results in the induction of the enzymes for histidine catabolism. 3. The pathway of histidine degradation in this organism, a non-fluorescent Pseudomonad, is shown to be the same as that operating in Pseudomonas fluorescens and Pseudomonas putida. It consists of the successive formation of urocanate, imidazol-4-on-5-ylpropionate, N-formimino-l-glutamate, N-formyl-l-glutamate and glutamate. 4. Whole cells of P. testosteroni accumulate urocanate in the reaction mixture when incubated with imidazolylpropionate, but only after an adaptive lag period which is removed by previous growth on imidazolylpropionate as the source of carbon. 5. Imidazolyl-lactate is oxidized to imidazolylpyruvate, which then gives rise to histidine by specific transamination with l-glutamate. 6. Cells grown on histidine, urocanate or imidazolylpropionate are also able to degrade imidazolyllactate. 7. Mutants lacking urocanase are unable to grow on imidazolylpropionate, imidazolyl-lactate, histidine or urocanate. One with impaired histidase activity cannot utilize histidine or imidazolyl-lactate, but grows normally on imidazolylpropionate or urocanate. A mutant unable to grow on imidazolylpropionate is indistinguishable from the wild-type with respect to growth on histidine, imidazolyl-lactate or urocanate. 8. Thus it is established that imidazolyl-lactate is metabolized via histidine whereas imidazolylpropionate enters the histidine degradation pathway after conversion into urocanate.

Acrylates↗
PubMed1973

The control of the enzymes degrading histidine and related imidazolyl derivates in Pseudomonas testosteroni.

1. The induction of the enzymes for the degradation of l-histidine, imidazolylpropionate and imidazolyl-l-lactate in Pseudomonas testosteroni was investigated. 2. The activities of histidine ammonia-lyase, histidine-2-oxoglutarate aminotransferase and urocanase are consistent with these enzymes being subject to co-ordinate control under most growth conditions. However, a further regulatory mechanism may be superimposed for histidase alone under conditions where degradation of histidine must take place for growth to occur. 3. Experiments with a urocanase(-) mutant show that urocanate is an inducer for the enzymes given above and also for N-formiminoglutamate hydrolyase and N-formylglutamate hydrolase. 4. N-Formiminoglutamate hydrolase and N-formylglutamate hydrolase are also induced by their substrates, and it is suggested that these two enzymes may be different gene products from those expressed in the presence of urocanate. 5. Induction of the enzyme system for the oxidation of imidazolylpropionate is dependent on exposure of cells to this compound.

Biological Transport↗
PubMed1973

Lethal effect of rifampicin in Bacillus subtilis as a complicating factor in the assessment of the lifetime of messenger ribonucleic acid.

The bactericidal action of rifampicin was compared with that of chloramphenicol in growing and in sporulating cultures of Bacillus subtilis 168. Chloramphenicol kills cells only very slowly, but exposure to rifampicin kills over 95% of cells in a few minutes, causing gross physical damage, which is visible in both phase-contrast and electron microscopy. This is accompanied by a fall in O(2) consumption and by lysis. Experiments with synchronized cultures showed that susceptibility to the lethal effect of rifampicin is greater when the cells are dividing. The results suggest that the synthesis of some species of RNA other than mRNA may be necessary for the maintenance of cell integrity, although experiments with actinomycin D do not altogether fit this interpretation. However, we conclude that rifampicin is too toxic to use as an antibiotic for assessing the lifetime of mRNA.

Bacillus subtilis↗
PubMed1973

Use of constructed double mutants for determining the temporal order of expression of sporulation genes in Bacillus subtilis.

Double mutants containing two Spo mutations concerned with different stages of sporulation were constructed. In these, the phenotype that is exhibited is that of the earlier sporulation block. The same procedure was applied to sporulation mutants damaged in the same stage of development. The results provide a basis for placing in a temporal order different mutations concerned in stage II and stage IV of spore development. In general, the order indicated by the phenotypes of the double mutants is in agreement with the order derived on biochemical grounds. Double oligosporogenous mutants have also been constructed. Their sporulation incidence is roughly equal to the product of the incidences of the parent strains, idicating that separate factors are involved in overcoming each oligosporogenous block. The number of dependent sequential steps in sporulation is estimated as not less than about 12.

Bacillus subtilis↗