Zong Yinong, Mazmanian Sarkis K, Schneewind Olaf, Narayana Sthanam V L
Center for Biophysical Sciences and Engineering, School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Structure. 2004 Jan;12(1):105-12. doi: 10.1016/j.str.2003.11.021.
Many surface proteins of Gram-positive bacteria, which play important roles during the pathogenesis of human infections, are anchored to the cell wall envelope by a mechanism requiring sortases. Sortase B, a cysteine transpeptidase from Staphylococcus aureus, cleaves the C-terminal sorting signal of IsdC at the NPQTN motif and tethers the polypeptide to the pentaglycine cell wall cross-bridge. During catalysis, the active site cysteine of sortase and the cleaved substrate form an acyl intermediate, which is then resolved by the amino group of pentaglycine cross-bridges. We report here the crystal structures of SrtBDeltaN30 in complex with two active site inhibitors, MTSET and E64, and with the cell wall substrate analog tripleglycine. These structures reveal, for the first time, the active site disposition and the unique Cys-Arg catalytic machinery of the cysteine transpeptidase, and they also provide useful information for the future design of anti-infective agents against sortases.
许多革兰氏阳性菌的表面蛋白在人类感染发病过程中发挥重要作用，它们通过一种需要分选酶的机制锚定在细胞壁包膜上。分选酶B是一种来自金黄色葡萄球菌的半胱氨酸转肽酶，它在NPQTN基序处切割IsdC的C端分选信号，并将多肽连接到五肽聚糖细胞壁交联桥上。在催化过程中，分选酶的活性位点半胱氨酸与切割后的底物形成酰基中间体，然后由五肽聚糖交联桥的氨基将其分解。我们在此报告了SrtBDeltaN30与两种活性位点抑制剂MTSET和E64以及细胞壁底物类似物三肽甘氨酸形成复合物的晶体结构。这些结构首次揭示了半胱氨酸转肽酶的活性位点布局和独特的半胱氨酸-精氨酸催化机制，也为未来设计针对分选酶的抗感染药物提供了有用信息。
