Determinants of Murein Hydrolase Targeting to Cross-wall of Staphylococcus aureus Peptidoglycan
Determinants of Murein Hydrolase Targeting to Cross-wall of Staphylococcus aureus Peptidoglycan
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DOI：
10.1074/jbc.m111.336404
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发表时间：
2012-03-23
影响因子：
4.8
通讯作者：
Schneewind, Olaf
中科院分区：
文献类型：
--
作者：
Frankel, Matthew B.;Schneewind, Olaf
真核或原核来源的细胞表达具有与细菌细胞壁包膜相关的 LysM 结构域的蛋白质。 LysM 结构域与微生物细胞壁相互作用的分子特性尚未确定。金黄色葡萄球菌是一种球形微生物，分泌两种具有 LysM 结构域的胞壁质水解酶：Sle1 和 LytN。我们在此表明，Sle1 和 LytN 的 LysM 结构域将胞壁质水解酶引导至横壁附近的葡萄球菌包膜，即用于肽聚糖合成的细胞中部区室。 LysM 结构域与葡萄球菌肽聚糖的重复二糖 β-N-乙酰胞壁酸、(1 -> 4)-β-N-乙酰葡糖胺相关。用壁磷壁酸（一种与壁蛋白连接单元相连的核糖醇磷酸聚合物）对 N-乙酰胞壁酸进行修饰，可防止 LysM 结构域与肽聚糖结合。在葡萄球菌 tagO 突变体中，LytN 和 Sle1 的跨壁定位被消除，该突变体的壁磷壁酸合成存在缺陷。我们提出了一个模型，其中 LysM 结构域确保 LytN 和 Sle1 的间隔定位，然后进行肽聚糖的裂解，从而在跨壁中暴露新的 LysM 结合位点并分离细菌细胞。
Cells of eukaryotic or prokaryotic origin express proteins with LysM domains that associate with the cell wall envelope of bacteria. The molecular properties that enable LysM domains to interact with microbial cell walls are not yet established. Staphylococcus aureus, a spherical microbe, secretes two murein hydrolases with LysM domains, Sle1 and LytN. We show here that the LysM domains of Sle1 and LytN direct murein hydrolases to the staphylococcal envelope in the vicinity of the crosswall, the mid-cell compartment for peptidoglycan synthesis. LysM domains associate with the repeating disaccharide beta-N-acetylmuramic acid, (1 -> 4)-beta-N-acetylglucosamine of staphylococcal peptidoglycan. Modification of N-acetylmuramic acid with wall teichoic acid, a ribitol-phosphate polymer tethered to murein linkage units, prevents the LysM domain from binding to peptidoglycan. The localization of LytN and Sle1 to the crosswall is abolished in staphylococcal tagO mutants, which are defective for wall teichoic acid synthesis. We propose a model whereby the LysM domain ensures septal localization of LytN and Sle1 followed by processive cleavage of peptidoglycan, thereby exposing new LysM binding sites in the cross-wall and separating bacterial cells.