Anchor Structure of Staphylococcal Surface Proteins
Anchor Structure of Staphylococcal Surface Proteins
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DOI：
10.1074/jbc.273.44.29143
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发表时间：
1998-10
期刊：
影响因子：
--
通讯作者：
H. Ton-That;H. Labischinski;B. Berger-Bächi;O. Schneewind
中科院分区：
文献类型：
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作者：
H. Ton-That;H. Labischinski;B. Berger-Bächi;O. Schneewind
金黄色葡萄球菌的表面蛋白通过需要具有保守的LPXTG基序的COOH末端分选信号的机制共价连接到细菌细胞壁。LPXTG基序的苏氨酸和甘氨酸之间的切割释放苏氨酸的羧基以与葡萄球菌肽聚糖中的五糖基交叉桥形成酰胺键。在这里，我们问是否改变肽聚糖跨桥干扰的分选反应，并调查表面蛋白锚定的葡萄球菌突变体。S.在femA、femB、femAB或femAX基因中携带突变的金黄色葡萄球菌菌株合成改变的交叉桥，并且这些菌株中的每一种都显示出降低的分选活性。从thefem突变体中纯化的细胞壁锚结构的表征表明，表面蛋白连接到含有1个、3个或5个甘氨酰残基的交叉桥，但不连接到不含甘氨酸的胞肽中赖氨酰的ε-氨基。当在合成具有单甘氨酰、三甘氨酰和五甘氨酰以及四甘氨酰-单丝氨酰的交叉桥的femAB菌株中测试时，发现表面蛋白主要锚定至五残基交叉桥（五甘氨酰或四甘氨酰-单丝氨酰）。因此，尽管野生型肽聚糖似乎是分选反应的优选底物，但改变的细胞壁横桥可以连接到表面蛋白的COOH末端。
Surface proteins of Staphylococcus aureus are covalently linked to the bacterial cell wall by a mechanism requiring a COOH-terminal sorting signal with a conserved LPXTG motif. Cleavage between the threonine and the glycine of the LPXTG motif liberates the carboxyl of threonine to form an amide bond with the pentaglycyl cross-bridge in the staphylococcal peptidoglycan. Here, we asked whether altered peptidoglycan cross-bridges interfere with the sorting reaction and investigated surface protein anchoring in staphylococcalfem mutants. S. aureus strains carrying mutations in the femA, femB, femAB, or the femAX genes synthesize altered cross-bridges, and each of these strains displayed decreased sorting activity. Characterization of cell wall anchor structures purified from thefem mutants revealed that surface proteins were linked to cross-bridges containing one, three, or five glycyl residues, but not to the ε-amino of lysyl in muropeptides without glycine. When tested in a femAB strain synthesizing cross-bridges with mono-, tri-, and pentaglycyl as well as tetraglycyl-monoseryl, surface proteins were found anchored mostly to the five-residue cross-bridges (pentaglycyl or tetraglycyl-monoseryl). Thus, although wild-type peptidoglycan appears to be the preferred substrate for the sorting reaction, altered cell wall cross-bridges can be linked to the COOH-terminal end of surface proteins.