Teichoic acid and lipid metabolism during sporulation of Bacillus megaterium KM.
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ABSTRACT:
SUBMITTER: Johnstone K
PROVIDER: S-EPMC1158131 | biostudies-other | 1982 Feb
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Accumulation of Ca2+ in Bacilli occurs during stages IV to VI of sporulation. Ca2+ uptake into the sporangium was investigated in Bacillus megaterium KM in protoplasts prepared in stage III of sporulation and cultured to continue sporulation. These protoplasts and whole cells exhibit essentially identical Ca2+ uptake, which is compared with that of forespores isolated in stage V of sporulation. Ca2+, uptake into both sporangial protoplasts and isolated forespores occurs by Ca2+-specific carrier-mediated processes. However, protoplasts exhibit a Km value of 31 micrometer, and forespores have a Km value of 2.1 mM. Sporangial protoplasts accumulate Ca2+ against a concentration gradient. In contrast, Ca2+ uptake into isolated forespores is consistent with downhill transfer in which both rate and extent of uptake are affected by the external Ca2+ concontration. Dipicolinic acid has no effect on Ca2+ uptake by isolated forespores, apart from decreasing the external Ca2+ concentration by chelation. A model for sporulation-specific Ca2+ accumulation is proposed, in which Ca2+ is transported into the sporangium, resulting in a concentration of 3--9 mM in the mother-cell cytoplasm. This high concentration of Ca2+ enables carrier-mediated transfer down a concentration gradient into the forespore compartment, where a low free Ca2+ concentration is maintained by complexing with dipicolinic acid.
| S-EPMC1186221 | biostudies-other
Project description:Ca2+ accumulation and endogenous respiration of sporulating Bacillus megaterium are inhibited to the same extent by electron-transport of inhibitors and the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone, suggesting that Ca2+ is accumulated by an active transport process. Forespores isolated in stage V of sporulation demonstrated Ca2+-specific carrier-mediated Ca2+ uptake, consistent with downhill transfer [Hogarth & Ellar (1978) Biochem. J. 176, 197-203]. In the present studies forespore Ca2+ uptake was unaffected by carbonyl cyanide p-trifluoromethoxyphenylhydrazone and by concentrations of respiratory inhibitor that inhibited forespore endogenous respiration by 85%. These data suggest that Ca2+ enters the isolated forespore by facilitated diffusion. Ca2+ uptake into sporulating protoplasts was completely inhibited by concentrations of respiratory inhibitors that had no effect on either Ca2+ uptake or respiration of stage-V forespores, but which resulted in inhibition of mother-cell membrane NADH oxidase. These results indicate that the mother-cell membrane is a site for active transport of Ca2+ into the sporulating cell. The effects of the adenosine triphosphatase inhibitor dicyclohexylcarbodi-imide on mother-cell membrane adenosine triphosphatase, NADH oxidase and protoplast Ca2+ uptake were examined.
| S-EPMC1186563 | biostudies-other
Project description:Lipid synthesis during the cell duplication cycle of Bacillus megaterium KM and Escherichia coli was studied by glycerol incorporation both in synchronized cultures and in unsynchronized exponentially growing populations subsequently fractionated according to size (and age). A large transient increase in the rate of incorporation per unit cell mass was observed around the time of cell division, probably reflecting the synthesis of the division septum.
| S-EPMC1185195 | biostudies-other
Project description:The germination response of spores of Bacillus megaterium KM, as measured by loss of A600, is more than 95% inhibited by 1 mM-HgCl2. Two Hg2+-sensitive sites (referred to as 'sites I and II') have been identified during germination. Site I represents a pre-commitment event and can be protected from HgCl2 by 50 mM-D-alanine, whereas site II represents a post-commitment event and is not D-alanine-protectable. At 1 mM-HgCl2, 25% of the spore population becomes committed to germinate, but an A600 loss of less than 5% occurs. In this system, loss of heat resistance was associated with commitment, whereas selective cortex hydrolysis, release of pyridine-2,6-dicarboxylic acid, Zn2+ and soluble peptidoglycan, as well as loss of refractility, were identified as post-commitment events. The commitment event was reversibly inhibited by several proteinase inhibitors and a membrane bulking agent. A model of spore germination based on these results is presented.
| S-EPMC1147068 | biostudies-other
Project description:A protein of apparent mol.wt. 35000 that is extractable from the purified coat fraction of Bacillus megaterium KM spores is synthesized during sporulation as a precursor protein from which a 12-13 amino acid peptide is removed. Cleavage of this small peptide is delayed until 60-90 min after precursor synthesis and is concomitant with the morphological appearance of stage VI. The addition of chloramphenicol, subsequent to precursor synthesis, prevents the appearance of this late processing event. Two-dimensional non-equilibrium pH-gradient gel electrophoresis of the integument extract of forespores isolated at stage V from sporangia pulse-labelled with L-[35S]methionine 1 h before isolation, revealed both unprocessed and processed components. Similar analysis of total protein from the corresponding mother cells revealed only the unprocessed component in relatively small amounts, suggesting that, although the protein may be synthesized in the mother-cell compartment, processing may be restricted to the forespore. Peptide analysis by limited proteolysis was used to examine the relationship between the 35000- and a 17500-mol.wt. coat protein. The possible implications of limited proteolytic processing to maturation of the spore coat are discussed.
| S-EPMC1154239 | biostudies-other
Project description:Zinc release is the first quantitatively significant event detected during the triggering of Bacillus megaterium KM spore germination. Of the total spore Zn2+ pool 25% is released from non-heat-activated spores within 4 min of triggering germination. During this period only 10% of the spore population becomes irreversibly committed to germinate. The investigation of a putative role for Zn2+ in the germination trigger mechanism has established a relationship between the rate and extent of Zn2+ release and the stimulation of spore germination by heat activation. Furthermore, a correlation can be demonstrated between the extent of zinc release from spore populations and the time required to obtain 50% commitment of these populations to germinate over a wide temperature range. These findings have been used to expand a recently published model for the triggering of bacterial spore germination.
| S-EPMC1153977 | biostudies-other
Project description:The spore-coat fraction from Bacillus megaterium KM, when prepared by extraction of lysozyme-digested integuments with SDS (sodium dodecyl sulphate) and urea, contains three N-terminal residues and a major component of apparent mol.wt. 17500. Electron microscopy of this fraction shows it to consist of an ordered multilamellar structure similar to that which forms the coat region of intact spores. The 17500-dalton protein, which has been purified to homogeneity, has an N-terminal methionine residue, has high contents of glycine, proline, cysteine and acidic amino acids and readily polymerized even in the presence of thiol-reducing agents. It is first synthesized between late Stage IV and early Stage V, which correlates with the morphological appearance of spore coat. Before Stage VI the 17500-dalton protein is extractable from sporangia by SDS in the absence of thiol-reducing reagents. Between Stage VI and release of mature spores the protein becomes resistant to extraction by SDS unless it is supplemented by a thiol-reducing reagent. In addition to that of the spore-coat protein, the timing of synthesis of all the integument proteins was analysed by SDS/polyacrylamide-gel electrophoresis and non-equilibrium pH-gradient electrophoresis. Several integument proteins are conservatively synthesized from as early as 1h after the end of exponential growth (t1), which may reflect protein incorporation into the spore outer membrane.
| S-EPMC1158096 | biostudies-other
Project description:While vegetative Bacillus subtilis cells and mature spores are both surrounded by a thick layer of peptidoglycan (PG, a polymer of glycan strands cross-linked by peptide bridges), it has remained unclear whether PG surrounds prespores during engulfment. To clarify this issue, we generated a slender ?ponA mutant that enabled high-resolution electron cryotomographic imaging. Three-dimensional reconstructions of whole cells in near-native states revealed a thin PG-like layer extending from the lateral cell wall around the prespore throughout engulfment. Cryotomography of purified sacculi and fluorescent labelling of PG in live cells confirmed that PG surrounds the prespore. The presence of PG throughout engulfment suggests new roles for PG in sporulation, including a new model for how PG synthesis might drive engulfment, and obviates the need to synthesize a PG layer de novo during cortex formation. In addition, it reveals that B. subtilis can synthesize thin, Gram-negative-like PG layers as well as its thick, archetypal Gram-positive cell wall. The continuous transformations from thick to thin and back to thick during sporulation suggest that both forms of PG have the same basic architecture (circumferential). Endopeptidase activity may be the main switch that governs whether a thin or a thick PG layer is assembled.
| S-EPMC3893088 | biostudies-literature
Project description:UTP-glucose-1-phosphate uridylyltransferases are enzymes that produce UDP-glucose from UTP and glucose-1-phosphate. In Bacillus subtilis 168, UDP-glucose is required for the decoration of wall teichoic acid (WTA) with glucose residues and the formation of glucolipids. The B. subtilis UGPase GtaB is essential for UDP-glucose production under standard aerobic growth conditions, and gtaB mutants display severe growth and morphological defects. However, bioinformatics predictions indicate that two other UTP-glucose-1-phosphate uridylyltransferases are present in B. subtilis. Here, we investigated the function of one of them named YngB. The crystal structure of YngB revealed that the protein has the typical fold and all necessary active site features of a functional UGPase. Furthermore, UGPase activity could be demonstrated in vitro using UTP and glucose-1-phosphate as substrates. Expression of YngB from a synthetic promoter in a B. subtilis gtaB mutant resulted in the reintroduction of glucose residues on WTA and production of glycolipids, demonstrating that the enzyme can function as UGPase in vivo. When WT and mutant B. subtilis strains were grown under anaerobic conditions, YngB-dependent glycolipid production and glucose decorations on WTA could be detected, revealing that YngB is expressed from its native promoter under anaerobic condition. Based on these findings, along with the structure of the operon containing yngB and the transcription factor thought to be required for its expression, we propose that besides WTA, potentially other cell wall components might be decorated with glucose residues during oxygen-limited growth condition.
| S-EPMC7961091 | biostudies-literature
Project description:1. Particulate enzyme preparations obtained from Bacillus stearothermophilus B65 by digestion with lysozyme were shown to catalyse teichoic acid synthesis. With CDP-glycerol as sole substrate the preparations synthesized 1,3-poly(glycerol phosphate). It was characterized by alkaline hydrolysis, by glucosylation to the alkali-stable 2-glucosyl-1,3-poly(glycerol phosphate) with excess of UDP-glucose and a Bacillus subtilis Marburg enzyme system, by degradation of this latter product with 60%HF and periodate oxidation of the resulting glucosylglycerol. The specificity of the B. subtilis system previously reported (Glaser & Burger, 1964), was confirmed in the present work. 2. Pulse-labelling experiments, followed by periodate oxidation of the product and isolation of formaldehyde from the glycerol terminus of the polymer, showed that the B. stearothermophilus enzyme system transferred glycerol phosphate units to the glycerol end of the chain. The transfer reaction was irreversible. It was not determined if these poly(glycerol phosphate) chains were synthesized de novo, but it was shown that the newly synthesized oligomers were bound to much larger molecules. 3. When the B. stearothermophilus enzyme system was supplied with both CDP-glycerol and UDP-glucose, 1-glucosyl-2,3-poly(glycerol phosphate) was synthesized in addition to the 1,3-isomer. The former polymer was characterized by acid and alkaline hydrolysis, degradation with HF and periodate oxidation of the resulting glucosylglycerol, and periodate oxidation of the intact polymer followed by mild acid hydrolysis. This latter procedure removed the glucose substituents without disrupting the poly(glycerol phosphate) chain. 4. The poly(glycerol phosphate) isomers were distinguished by glucosylation with the B. subtilis enzymes and alkaline hydrolysis, the 2,3-isomer remaining alkali-labile. The proportion of 2,3-poly(glycerol phosphate) in the product increased with increasing amounts of UDP-glucose in the incubation mixture, but the total glycerol phosphate incorporated into products remained constant. It is suggested that the synthetic pathways of the two poly(glycerol phosphate) species may share a rate-limiting step.
| S-EPMC1166238 | biostudies-other