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B Setlow

Publications and source records attributed to B Setlow.

At least 73 records · Page 4Linked to original sources
PubMed1988

Decreased UV light resistance of spores of Bacillus subtilis strains deficient in pyrimidine dimer repair and small, acid-soluble spore proteins.

Loss of small, acid-soluble spore protein alpha reduced spore UV resistance 30- to 50-fold in Bacillus subtilis strains deficient in pyrimidine dimer repair, but gave only a 5- to 8-fold reduction in UV resistance in repair-proficient strains. However, both repair-proficient and -deficient spores lacking this protein had identical heat and gamma-radiation resistance.

Bacillus subtilis↗
PubMed1988

Immunoelectron microscopic localization of small, acid-soluble spore proteins in sporulating cells of Bacillus subtilis.

Small, acid-soluble spore proteins SASP-alpha, SASP-beta, and SASP-gamma as well as a SASP-beta-lacZ gene fusion product were found only within the forespore compartment of sporulating Bacillus subtilis cells by using immunoelectron microscopy. The alpha/beta-type SASP were associated almost exclusively with the forespore nucleoid, while SASP-gamma was somewhat excluded from the nucleoid. These different locations of alpha/beta-type and gamma-type small, acid-soluble spore proteins within the forespore are consistent with the different roles for these two types of proteins in spore resistance to UV light.

Bacillus subtilis↗
PubMed1987

Thymine-containing dimers as well as spore photoproducts are found in ultraviolet-irradiated Bacillus subtilis spores that lack small acid-soluble proteins.

Dormant spores of a Bacillus subtilis mutant that lacks two major small, acid-soluble spore proteins are very sensitive to UV irradiation, which in spores generates about half the amount of thymine-containing dimers formed by comparable irradiation of vegetative cells. Irradiation of mutant spores also produces spore photoproducts, but again only about one-half the amount formed in comparably irradiated wild-type spores. These findings suggest that the high UV sensitivity of the mutant spores is due to the production of pyrimidine dimers, which are not found in UV-irradiated wild-type spores, and that the high level of small, acid-soluble proteins found in wild-type spores is directly involved in spore UV resistance by facilitating a conformational change in spore DNA, preventing pyrimidine dimer formation.

Bacillus subtilis↗
PubMed1986

Cloning and nucleotide sequencing of genes for small, acid-soluble spore proteins of Bacillus cereus, Bacillus stearothermophilus, and "Thermoactinomyces thalpophilus".

As found previously with other Bacillus species, spores of B. stearothermophilus and "Thermoactinomyces thalpophilus" contained significant levels of small, acid-soluble spore proteins (SASP) which were rapidly degraded during spore germination and which reacted with antibodies raised against B. megaterium SASP. Genes coding for a B. stearothermophilus and a "T. thalpophilus" SASP as well as for two B. cereus SASP were cloned, their nucleotide sequences were determined, and the amino acid sequences of the SASP coded for were compared. Strikingly, all of the amino acid residues previously found to be conserved in this group of SASP both within and between two other Bacillus species (B. megaterium and B. subtilis) were also conserved in the SASP coded for by the B. cereus genes as well as those coded for by the genes from the more distantly related organisms B. stearothermophilus and "T. thalpophilus." This finding strongly suggests that there is significant selective pressure to conserve SASP primary sequence and thus that these proteins serve some function other than simply amino acid storage.

Amino Acid Sequence↗
PubMed1986

Cloning and nucleotide sequence of the Bacillus megaterium gene coding for small, acid-soluble spore protein B.

The Bacillus megaterium gene coding for small, acid-soluble spore protein (SASP) B was cloned and its nucleotide sequence was determined. The amino acid sequence predicted from the DNA sequence was identical to that determined previously for SASP B, with the exception of the amino-terminal methionine predicted from the gene sequence which is presumably removed posttranslationally and an asparagine residue predicted at position 21 which was originally identified as an aspartate residue. The mRNA encoded by the SASP B gene is synthesized for only a discrete period midway in sporulation, in parallel with mRNAs coding for other SASPs. The small size of the SASP B mRNA (365 nucleotides) indicated that the mRNA is monocistronic. The SASP B gene itself hybridized strongly to only one band in Southern blots of restriction enzyme digests of B. megaterium DNA, suggesting that the SASP B gene is not a member of a highly conserved multigene family, as is the case for other SASP genes.

Amino Acid Sequence↗
PubMed1983

Cloning of the gene for C protein, a low molecular weight spore-specific protein from Bacillus megaterium.

The structural gene for C protein, a low molecular weight spore-specific protein from Bacillus megaterium, has been cloned in Escherichia coli. Expression of the C-protein gene in E. coli requires an external transcription promoter and prevention of termination of transcription prior to transcription of all or part of the sequence coding for the C protein. The gene for the C protein is within a 5-kilobase DNA fragment, but this fragment does not code for either of the other two major low molecular weight spore proteins, suggesting that the structural genes for these proteins are not tightly linked.

Bacillus megaterium↗
PubMed1982

Noninvolvement of the spore cortex in acquisition of low-molecular-weight basic proteins and UV light resistance during Bacillus sphaericus sporulation.

Two major low-molecular weight, acid-soluble proteins (termed A and B proteins) were purified from Bacillus sphaericus spores and had properties similar to those of the analogous proteins from spores of other Bacillus species. These proteins were accumulated late in sporulation, when the developing spores became resistant to UV light, and were degraded during spore germination by a spore protease. A mutant of B. sphaericus unable to make spore cortex because of a block in diaminopimelic acid (DAP) biosynthesis accumulated and maintained levels of the A and B proteins similar to those in the DAP+ parent or the DAP- strain in which cortex formation was restored by growth with DAP. In addition, the DAP- strain grown without DAP acquired a level of UV light resistance identical to that of wild-type spores and at the time of appearance of the A and B proteins. These findings indicate that formation of little, if any, spore cortex is required for acquisition of UV light resistance or maintenance of high levels of A and B proteins. The data provide further support for a role of the A and B proteins in the spore's UV light resistance.

Bacillus↗
PubMed1981

Levels of H+ and other monovalent cations in dormant and germinating spores of Bacillus megaterium.

Previous investigators using the extent of uptake of the weak base methylamine to measure internal pH have shown that the pH in the core region of dormant spores of Bacillus megaterium is 6.3 to 6.5. Elevation of the internal pH of spores by 1.6 U had no significant effect on their degree of dormancy or their heat or ultraviolet light resistance. Surprisingly, the rate of methylamine uptake into dormant spores was slow (time for half-maximal uptake, 2.5 h at 24 degrees C). Most of the methylamine taken up by dormant spores was rapidly (time for half-maximal uptake, less than 3 min) released during spore germination as the internal pH of spores rose to approximately 7.5. This rise in internal spore pH took place before dipicolinic acid release, was not abolished by inhibition of energy metabolism, and during germination at pH 8.0 was accompanied by a decrease in the pH of the germination medium. Also accompanying the rise in internal spore pH during germination was the release of greater than 80% of the spores K+ and Na+. The K+ was subsequently reabsorbed in an energy-dependent process. These data indicate (i) that between pH 6.2 and 7.8 internal spore pH has little effect on dormant spore properties, (ii) that there is a strong permeability barrier in dormant spores to movement of charged molecules and small uncharged molecules, and (iii) that extremely early in spore germination this permeability barrier is breached, allowing rapid release of internal monovalent cations (H+, Na+, and K+).

Bacillus megaterium↗
PubMed1980

Measurements of the pH within dormant and germinated bacterial spores.

The pH within the core or central region of dormant spores of Bacillus cereus and B. megaterium is 6.3-6.4 irrespective of the external pH. However, the spore's internal pH rises to 7.3-7.5 upon germination. The low internal pH of the dormant spore may be a contributing factor to its metabolic dormancy.

Bacillus cereus↗
PubMed1979

Identification of an NADH-linked disulfide reductase from Bacillus megaterium specific for disulfides containing pantethine 4',4''-diphosphate moieties.

Bacillus megaterium contains an NADH-linked disulfide reductase that is specific for disulfides containing pantethine 4',4''-diphosphate moieties. This reductase is at its highest level in cells late in sporulation and in dormant spores, and could be involved in the formation and cleavage of coenzyme A-protein disulfides which take place late in sporulation and early in spore germination, respectively.

Bacillus megaterium↗
PubMed1979

Localization of low-molecular-weight basic proteins in Bacillus megaterium spores by cross-linking with ultraviolet light.

Two low-molecular-weight basic proteins, termed A and B proteins, comprise about 15% of the protein of dormant spores of Bacillus megaterium. Irradiation of intact dormant spores with ultraviolet light results in covalent cross-linking of the A and B proteins to other spore macromolecules. The cross-linked A and B proteins are precipitated by ethanol and can be solubilized by treatment with deoxyribonuclease (75%) or ribonuclease (25%). Irradiation of complexes formed in vitro between deoxyribonucleic acid (DNA) or ribonucleic acid and a mixture of the low-molecular-weight basic proteins from spores also resulted in cross-linking of A and B proteins to nucleic acids. The dose-response curves for formation of covalent cross-links were similar for irradiation of both a protein-DNA complex in vitro and intact spores. However, if irradiation was carried out in vitro under conditions where DNA-protein complexes were disrupted, no covalent cross-links were formed. These data suggest that significant amounts of the low-molecular-weight basic proteins unique to bacterial spores are associated with spore DNA in vivo.

Bacillus megaterium↗
PubMed1978

Levels of cyclic GMP in dormant, germinated, and outgrowing spores and growing and sporulating cells of Bacillus megaterium.

The level of cyclic GMP was less than one molecule per organism in dormant, germinated, and outgrowing spores of Bacillus megaterium. A significant level (approximately 8 pmol/g, dry weight) of cyclic GMP was found in early to mid-log phase cells, but the level fell to below 0.2 pmol/g, dry weight, in late-log phase and only rose slightly to approximately 0.9 pmol/g, dry weight, in stationary phare. No significant amount of cyclic GMP was detected in the growth medium at any time.

Bacillus megaterium↗
PubMed1977

Levels of oxidized and reduced pyridine nucleotides in dormant spores and during growth, sporulation, and spore germination of Bacillus megaterium.

Dormant spores of Bacillus megaterium contained no detectable reduced nicotinamide adenine dinucleotide (NADH) or reduced nicotinamide adenine dinucleotide phosphate (NADPH) despite significant levels of the oxidized forms of these nucleotides (NAD and NADP). During the first minutes of spore germination there was rapid accumulation of NADH and NADPH. However, this accumulation followed the fall in optical density that is characteristic of the initiation of spore germination. Accumulation of NADH and NADPH early in germination was not blocked by fluoride or cyanide, and it occurred even when germination was carried out in the absence of an exogenous source of reducing power. In addition to pyridine nucleotide reduction, de novo synthesis also began early in germination as the pyridine nucleotide levels increased to those found in growing cells. Midlog-phase cells grown in several different media had 20 to 35 times as much total pyridine nucleotide as did dormant spores. However, as growth and sporulation proceeded, the NADH plus NAD level fell four- to fivefold whereas the NADPH plus NADP level fell by a lesser amount. From min 10 of spore germination until midway through sporulation the value for the ratio of NADH/NAD is about 0.1 (0.03 to 0.18) while the ratio of NADPH/ANDP is about 1.4 (0.3 to 2.4). Comparison of these ratios in log-phase versus stationary phase (sporulation) growth in all three growth media tested did not reveal any common pattern of changes.

Bacillus megaterium↗
PubMed1977

Levels of small molecules and enzymes in the mother cell compartment and the forespore of sporulating Bacillus megaterium.

We have determined the amounts of a number of small molecules and enzymes in the mother cell compartment and the developing forespore during sporulation of Bacillus megaterium. Significant amounts of adenosine 5'-triphosphate and reduced nicotinamide adenine dinucleotide were present in the forespore compartment before accumulation of dipicolinic acid (DPA), but these compounds disappeared as DPA was accumulated. 3-Phosphoglyceric acid (3-PGA) accumulated only within the developing forespore, beginning 1 to 2 h before DPA accumulation. Throughout its development the forespore contained constant levels of enzymes of both 3-PGA synthesis (phosphoglycerate kinase and glyceraldehyde-3-phosphate dehydrogenase) and 3-PGA utilization (phosphoglycerate mutase, enolase, and pyruvate kinase) at levels similar to those in the mother cell and the dormant spore. Despite the presence of enzymes for 3-PGA utilization, this compound was stable within isolated forespores. Two acid-soluble proteins (A and B proteins) also accumulated only in the forespore, beginning 1 to 2 h before DPA accumulation. At this time the specific protease involved in degradation of the A and B proteins during germination also appeared, but only in the forespore compartment. Nevertheless, the A and B proteins were stable within isolated forespores. Arginine and glutamic acid accumulated within the forespore in parallel with DPA accumulation. The forespore also contained the enzyme arginase at a level similar to that in the mother cell and a level of glutamic acid decarboxylase 2- to 25-fold higher than that in the mother cell, depending on when in sporulation the forespores were isolated. The specific activities of several other enzymes (protease active on hemoglobin, ornithine transcarbamylase, malate dehydrogenase, aconitase, and isocitrate dehydrogenase) in forespores were about 10% or less of the values in the mother cell. Aminopeptidase was present at similar levels in both compartments; threonine deaminase was not found in either compartment.

Adenine Nucleotides↗
PubMed1977

Levels of acetyl coenzyme A, reduced and oxidized coenzyme A, and coenzyme A in disulfide linkage to protein in dormant and germinated spores and growing and sporulating cells of Bacillus megaterium.

Dormant spores of Bacillus megaterium were found to contain approximately 850 pmol of coenzyme A (CoA) per milligram of dry weight. Of this total, less than 1.5% was acetyl-CoA, 25% was CoA-disulfide, 43% was in disulfide linkage to protein, and the remainder was the free thiol. Dormand spores of Bacillus cereus and Clostridium bifermentans contained 700 and 600 pmol of CoA per milligram of dry weight, respectively; in both species approximately 45% of the CoA 45% of the CoA was in disulfide linkage to protein. During germination of spores of all three species, greater than 75% of the CoA-protein disulfides were cleaved. In B. megaterium, cleavage of these disulfides during spore germination did not require exogenous metabolites and occurred at about the same time as the initiation of germination. Much of the CoA was converted to acetyl-CoA at this time. Dormant spores also contained reduced nicotinamide adenine dinucleotide-dependent CoA-disulfide reductase at levels higher than those in other stages of growth. The level of total CoA in the growing cells was two- to three-fold higher than in spores. This level remained constant throughout growth and sporulation, but less than 2% of the total cellular CoA was in disulfide linkage to protein until late in sporulation. The CoA-protein disulfides accumulated exclusively within the developing spore at about the time when dipicolinic acid was accumulated.

Acetyl Coenzyme A↗
PubMed1977

Production of large amounts of acetate during germination of Bacillus megaterium spores in the absence of exogenous carbon sources.

When Bacillus megaterium spores germinate in the absence of an exogenous carbon source, the first minutes of germination are accompanied by production of large amounts (approximately 70 nmol/mg of dry spores) of acetate and much smaller amounts of pyruvate and lactate. The majority of these compounds are excreted into the medium. Exogenous pyruvate and alanine are also converted to CO2 and acetate by germinating spores, presumably by using the pyruvate dehydrogenase that is present in dormant spores. These data suggest that the 3-phosphoglyceric acid stores in the dormant spore and alanine generated by proteolysis early in germination can be catabolized to acetate during germination with production of large amounts of reduced nicotinamide adenine dinucleotide, acetyl coenzyme A, and adenosine 5'-triphosphate.

Acetates↗