The staphostatin-staphopain complex - A forward binding inhibitor in complex with its target cysteine protease
The staphostatin-staphopain complex - A forward binding inhibitor in complex with its target cysteine protease
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DOI：
10.1074/jbc.m302926200
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发表时间：
2003-10-17
影响因子：
4.8
通讯作者：
Bochtler, M
中科院分区：
文献类型：
--
作者：
Filipek, R;Rzychon, M;Bochtler, M
葡萄球菌抑制素是金黄色葡萄球菌主要分泌的半胱氨酸蛋白酶葡萄球菌蛋白酶的内源性抑制剂。我们最近的晶体结构的staphostatin B已经表明，这种抑制剂形成一个混合的，八链β-桶具有统计学显着的相似性，脂质运载蛋白，但不是半胱氨酸蛋白酶抑制剂。我们现在提出的1.8埃晶体结构的葡萄球菌抑制素B与其目标蛋白酶的失活突变体的复合物。该复合物通过广泛的相互作用结合在一起，总表面积为2300埃（2）。对于半胱氨酸蛋白酶抑制剂来说，出乎意料的是，葡萄球菌蛋白酶抑制素B以几乎底物样的方式结合葡萄球菌蛋白酶B。抑制剂多肽链正向穿过蛋白酶活性位点裂缝，在P2至P2'位置具有残基IG-TS。无论是在自由和复合形式，P1甘氨酸残基的抑制剂是在一个主链构象只有接近甘氨酸。该残基中的突变导致抑制剂对蛋白酶的亲和力丧失，并将抑制剂转化为底物。
Staphostatins are the endogenous inhibitors of the major secreted cysteine proteases of Staphylococcus aureus, the staphopains. Our recent crystal structure of staphostatin B has shown that this inhibitor forms a mixed, eight-stranded beta-barrel with statistically significant similarity to lipocalins, but not to cystatins. We now present the 1.8-Angstrom crystal structure of staphostatin B in complex with an inactive mutant of its target protease. The complex is held together through extensive interactions and buries a total surface area of 2300 Angstrom(2). Unexpectedly for a cysteine protease inhibitor, staphostatin B binds to staphopain B in an almost substrate-like manner. The inhibitor polypeptide chain runs through the protease active site cleft in the forward direction, with residues IG-TS in P2 to P2' positions. Both in the free and complexed forms, the P1 glycine residue of the inhibitor is in a main chain conformation only accessible to glycines. Mutations in this residue lead to a loss of affinity of the inhibitor for protease and convert the inhibitor into a substrate.