Cell Wall Anchor Structure of BcpA Pili in Bacillus anthracis
Cell Wall Anchor Structure of BcpA Pili in Bacillus anthracis
复制标题
DOI：
10.1074/jbc.m806796200
复制
发表时间：
2008-12-26
影响因子：
4.8
通讯作者：
Schneewind, Olaf
中科院分区：
文献类型：
--
作者：
Budzik, Jonathan M.;Oh, So-Young;Schneewind, Olaf
革兰氏阳性菌中皮利的组装及其与细胞壁包膜的附着由分选酶介导。在蜡状芽孢杆菌及其近亲炭疽芽孢杆菌中，主要菌毛蛋白BcpA在其C-末端LPXTG基序分选信号的苏氨酸和甘氨酸之间被菌毛蛋白特异性分选酶D切割。所得到的酰基酶中间体被另一个BcpA亚基的YPKN基序内赖氨酸的侧链氨基的亲核攻击所缓解。组装的BcpA皮利的细胞壁锚定需要分选酶A，分选酶A也切割BcpA在其苏氨酸和甘氨酸残基之间的LPXTG分选信号。我们在这里表明，分选酶A和D只需要C-末端分选信号的BcpA底物裂解。与接受YPKN基序作为亲核试剂的分选酶D不同，分选酶A在芽孢杆菌细胞壁肽聚糖内的苏氨酸的BcpA C-末端羧基和二氨基庚二酸的侧链氨基之间形成酰胺键。这些结果代表了皮利的细胞壁锚结构的首次证明，该结构通过分选酶A沉积到许多不同微生物的包膜中。
Assembly of pili in Gram-positive bacteria and their attachment to the cell wall envelope are mediated by sortases. In Bacillus cereus and its close relative Bacillus anthracis, the major pilin protein BcpA is cleaved between the threonine and the glycine of its C-terminal LPXTG motif sorting signal by the pilin-specific sortase D. The resulting acyl enzyme intermediate is relieved by the nucleophilic attack of the side-chain amino group of lysine within the YPKN motif of another BcpA subunit. Cell wall anchoring of assembled BcpA pili requires sortase A, which also cleaves the LPXTG sorting signal of BcpA between its threonine and glycine residues. We show here that sortases A and D require only the C-terminal sorting signal of BcpA for substrate cleavage. Unlike sortase D, which accepts the YPKN motif as a nucleophile, sortase A forms an amide bond between the BcpA C-terminal carboxyl group of threonine and the side-chain amino group of diaminopimelic acid within the cell wall peptidoglycan of bacilli. These results represent the first demonstration of a cell wall anchor structure for pili, which are deposited by sortase A into the envelope of many different microbes.