Ton-That H, Faull K F, Schneewind O
Department of Microbiology & Immunology and Molecular Biology Institute, UCLA School of Medicine, Los Angeles, California 90095, USA.
J Biol Chem. 1997 Aug 29;272(35):22285-92. doi: 10.1074/jbc.272.35.22285.
Surface proteins of Staphylococcus aureus are anchored to the cell wall by a mechanism requiring a COOH-terminal sorting signal. Previous work demonstrated that the sorting signal is cleaved at the conserved LPXTG motif and that the carboxyl of threonine (T) is linked to the staphylococcal cell wall. By employing different cell wall lytic enzymes, surface proteins were released from the staphylococcal peptidoglycan and their COOH-terminal anchor structure was revealed by a combination of mass spectrometry and chemical analysis. The results demonstrate that surface proteins are linked to a branched peptide (NH2-Ala-gamma-Gln-Lys-(NH2-Gly5)-Ala-COOH) by an amide bond between the carboxyl of threonine and the amino of the pentaglycine cross-bridge that is attached to the epsilon-amino of lysyl. This branched anchor peptide is amide-linked to the carboxyl of N-acetylmuramic acid, thereby tethering the COOH-terminal end of surface proteins to the staphylococcal peptidoglycan.
金黄色葡萄球菌的表面蛋白通过一种需要COOH末端分选信号的机制锚定在细胞壁上。先前的研究表明，分选信号在保守的LPXTG基序处被切割，苏氨酸（T）的羧基与葡萄球菌细胞壁相连。通过使用不同的细胞壁裂解酶，表面蛋白从葡萄球菌肽聚糖中释放出来，并且通过质谱和化学分析相结合揭示了它们的COOH末端锚定结构。结果表明，表面蛋白通过苏氨酸羧基与连接到赖氨酰ε-氨基的五甘氨酸交联桥的氨基之间的酰胺键与支链肽（NH2-Ala-γ-Gln-Lys-(NH2-Gly5)-Ala-COOH）相连。这种支链锚定肽通过酰胺键与N-乙酰胞壁酸的羧基相连，从而将表面蛋白的COOH末端系在葡萄球菌肽聚糖上。
