Structural analysis of Bacillus subtilis 168 endospore peptidoglycan and its role during differentiation
Structural analysis of Bacillus subtilis 168 endospore peptidoglycan and its role during differentiation
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DOI：
10.1128/jb.178.21.6173-6183.1996
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发表时间：
1996-11-01
影响因子：
3.2
通讯作者：
Foster, SJ
中科院分区：
文献类型：
--
作者：
Atrih, A;Zollner, P;Foster, SJ
对枯草芽孢杆菌孢子壁肽聚糖的结构进行了研究，采用化学渗透孢子壁和酶解肽聚糖的方法制备了孢子壁肽聚糖。通过反相高效液相色谱、氨基酸分析和质谱分析，得到的多肽纯度为bb0 - 97%，结果表明，糖基骨架中49%的菌胺残基以δ -内酰胺形式存在，这种形式主要每秒发生一次，与菌胺酸δ -内酰胺残基相邻的糖苷键抵抗菌胺酶的作用。25.7%和23.3%分别被四肽和单一l -丙氨酸取代，只有2%的菌酸具有三肽侧链，可能构成原始细胞壁，其余的肽聚糖是孢子皮层，孢子肽聚糖在2.9%的菌酸残基上交联非常松散，比营养细胞壁少约11倍。菌株AA110的肽聚糖（dacB）的交联率（14.4%）是野生型的5倍，其δ -内酰胺、四肽和单l -丙氨酸取代基的比例分别为37.0%、46.3%和12.3%，这表明dacB蛋白（青霉素结合蛋白5*）在皮层生物合成中起作用。由于菌株AA107 （cwlD）的孢子肽聚糖完全缺乏菌酸δ -内酰胺残基，因此孢子特异性肽聚糖水解酶CwID在成熟孢子皮层结构的建立中起着关键作用，尽管肽聚糖结构发生了巨大变化，但孢子仍然稳定但无法发芽。δ -内酰胺和其他孢子肽聚糖结构特征在维持休眠、耐热性、并对发芽进行了讨论。
The structure of the endospore cell wall peptidoglycan of Bacillus subtilis has been examined, Spore peptidoglycan was produced by the development of a method based on chemical permeabilization of the spore coats and enzymatic hydrolysis of the peptidoglycan. The resulting muropeptides which were >97% pure were analyzed by reverse-phase high-performance liquid chromatography, amino acid analysis, and mass spectrometry, This revealed that 49% of the muramic acid residues in the glycan backbone were present in the delta-lactam form which occurred predominantly every second muramic acid, The glycosidic bonds adjacent to the muramic acid delta-lactam residues were resistant to the action of muramidases, Of the muramic acid residues, 25.7 and 23.3% were substituted with a tetrapeptide and a single L-alanine, respectively, Only 2% of the muramic acids had tripeptide side chains and may constitute the primordial cell wall, the remainder of the peptidoglycan being spore cortex, The spore peptidoglycan is very loosely cross-linked at only 2.9% of the muramic acid residues, a figure approximately 11-fold less than that of the vegetative cell wall, The peptidoglycan from strain AA110 (dacB) had fivefold-greater cross-linking (14.4%) than the wild type and an altered ratio of muramic acid substituents having 37.0, 46.3, and 12.3% delta-lactam, tetrapeptide, and single L-alanine, respectively, This suggests a role for the DacB protein (penicillin-binding protein 5*) in cortex biosynthesis, The sporulation-specific putative peptidoglycan hydrolase CwID plays a pivotal role in the establishment of the mature spore cortex structure since strain AA107 (cwlD) has spore peptidoglycan which is completely devoid of muramic acid delta-lactam residues, Despite this drastic change in peptidoglycan structure, the spores are still stable but are unable to germinate, The role of delta-lactam and other spore peptidoglycan structural features in the maintenance of dormancy, heat resistance, and germination is discussed.