Cross-linked peptidoglycan mediates lysostaphin binding to the cell wall envelope of Staphylococcus aureus
Cross-linked peptidoglycan mediates lysostaphin binding to the cell wall envelope of Staphylococcus aureus
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DOI：
10.1128/jb.188.7.2463-2472.2006
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发表时间：
2006-04-01
影响因子：
3.2
通讯作者：
Schneewind, O
中科院分区：
文献类型：
--
作者：
Gründling, A;Schneewind, O
模拟葡萄球菌溶葡萄球菌分泌溶葡萄球菌酶，一种裂解金黄色葡萄球菌细胞壁中的五甘氨酸跨桥的细菌素。溶葡萄球菌酶的C端细胞壁靶向结构域（CWT）是该细菌素选择性结合S.金黄色葡萄球菌细胞;然而，其分子靶点未知。我们使用纯化的绿色荧光蛋白与CWT融合（GFP-CWT）来揭示报告基因与葡萄球菌的种特异性关联。GFP-CWT结合S. aureus细胞以及纯化的肽聚糖囊。添加交联的胞壁素，连接到相互连接的壁肽的二糖，阻断GFP-CWT与葡萄球菌的结合，而胞壁素单体或溶葡萄球菌酶溶解的细胞壁片段没有。S.金黄色葡萄球菌菌株纽曼变体缺乏合成多糖荚膜（capFO）、聚-N-乙酰葡糖胺（icaAC）、脂蛋白（lgt）、细胞壁锚定蛋白（srtA）或脂磷壁酸的糖脂锚（ypfP）的能力，与野生型葡萄球菌类似地结合GFP-CWT。一个tagO突变株，在合成的聚核糖醇壁磷壁酸连接到细胞壁包膜缺陷，显示增加GFP-CWT结合。相比之下，减少肽聚糖交联（单甘氨酸交联桥）的量和长度的femAB突变显示出GFP-CWT结合的显著减少。因此，溶葡萄球菌酶的CWT结构域将细菌素引导至交联的肽聚糖，所述肽聚糖也充当其甘氨酰-甘氨酸内肽酶结构域的底物。
Staphylococcus simulans bv. staphylolyticus secretes lysostaphin, a bacteriocin that cleaves pentaglycine cross bridges in the cell wall of Staphylococcus aureus. The C-terminal cell wall-targeting domain (CWT) of lysostaphin is required for selective binding of this bacteriocin to S. aureus cells; however, the molecular target for this was unknown. We used purified green fluorescent protein fused to CWT (GFP-CWT) to reveal species-specific association of the reporter with staphylococci. GFP-CWT bound S. aureus cells as well as purified peptidoglycan sacculi. The addition of cross-linked murein, disaccharides linked to interconnected wall peptides, blocked GFP-CWT binding to staphylococci, whereas murein monomers or lysostaphin-solubilized cell wall fragments did not. S. aureus strain Newman variants lacking the capacity for synthesizing polysaccharide capsule (capFO), poly-N-acetylglucosamine (icaAC), lipoprotein (lgt), cell wall-anchored proteins (srtA), or the glycolipid anchor of lipoteichoic acid (ypfP) bound GFP-CWT similar to wild-type staphylococci. A tagO mutant strain, defective in the synthesis of polyribitol wall teichoic acid attached to the cell wall envelope, displayed increased GFP-CWT binding. In contrast, a femAB mutation, reducing both the amount and the length of peptidoglycan cross-linking (monoglycine cross bridges), showed a dramatic reduction in GFP-CWT binding. Thus, the CWT domain of lysostaphin directs the bacteriocin to cross-linked peptidoglycan, which also serves as the substrate for its glycyl-glycine endopeptidase domain.