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首页> 外文期刊>Journal of bacteriology >Peptidoglycan Structural Dynamics during Germination of Bacillus subtilis 168 Endospores
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Peptidoglycan Structural Dynamics during Germination of Bacillus subtilis 168 Endospores

机译：枯草芽孢杆菌168孢子萌发过程中的肽聚糖结构动力学

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Peptidoglycan structural dynamics during endospore germination ofBacillus subtilis 168 have been examined by muropeptide analysis. The first germination-associated peptidoglycan structural changes are detected within 3 min after the addition of the specific germinant l-alanine. We detected in the spore-associated material new muropeptides which, although they have slightly longer retention times by reversed-phase (RP)-high-pressure liquid chromatography (HPLC) than related ones in dormant spores, show the same amino acid composition and molecular mass. Two-dimensional nuclear magnetic resonance (NMR) analysis shows that the chemical changes to the muropeptides on germination are minor and are probably limited to stereochemical inversion. These new muropeptides account for almost 26% of the total muropeptides in spore-associated material after 2 h of germination. The exudate of germinated spores of B. subtilis 168 contains novel muropeptides in addition to those present in spore-associated material. Exudate-specific muropeptides have longer retention times, have no reducing termini, and exhibit a molecular mass 20 Da lower than those of related reduced muropeptides. These new products are anhydro-muropeptides which are generated by a lytic transglycosylase, the first to be identified in a gram-positive bacterium. There is also evidence for the activity of a glucosaminidase during the germination process. Quantification of muropeptides in spore-associated material indicates that there is a heterogeneous distribution of muropeptides in spore peptidoglycan. The spore-specific residue, muramic δ-lactam, is proposed to be a major substrate specificity determinant of germination-specific lytic enzymes, allowing cortex hydrolysis without any effect on the primordial cell wall.
机译：通过多肽分析研究了枯草芽孢杆菌 168的孢子萌发过程中肽聚糖的结构动力学。在添加特定的萌发剂1-丙氨酸后3分钟内，检测到了第一个与萌发相关的肽聚糖结构变化。我们在孢子相关物质中检测到了新的多肽，尽管它们通过反相（RP）-高压液相色谱（HPLC）的保留时间比休眠孢子中的相关肽的保留时间略长，但它们显示相同的氨基酸组成和分子质量二维核磁共振（NMR）分析表明，发芽过程中对多肽的化学变化很小，可能仅限于立体化学转化。这些新的多肽在发芽2小时后约占孢子相关物质中总多肽的26％。 B发芽孢子的渗出液。枯草芽孢杆菌168除与孢子相关物质中存在的多肽外，还含有新型的多肽。渗出物特异性的多聚肽具有更长的保留时间，没有还原末端，并且表现出比相关的还原的多聚肽低的20 Da的分子量。这些新产品是由水解转糖基酶产生的脱水多肽，这是第一个在革兰氏阳性细菌中被鉴定出来的。也有证据表明在发芽过程中氨基葡萄糖苷酶的活性。孢子相关物质中多肽的定量表明，在孢子肽聚糖中存在多肽的异质分布。孢子特异性残基，杂合性δ-内酰胺，被认为是发芽特异性裂解酶的主要底物特异性决定因素，可以使皮层水解而对原始细胞壁没有任何影响。

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