解析丝氨酸蛋白酶抑制的变构机制的抗体。
Unraveling the allosteric mechanism of serine protease inhibition by an antibody.
机构信息
Department of Protein Engineering, Genentech, Inc., South San Francisco, CA 94080, USA.
Department of Protein Engineering, Genentech, Inc., South San Francisco, CA 94080, USA; Department of Antibody Engineering, Genentech, Inc., South San Francisco, CA 94080, USA.
出版信息
Structure. 2009 Dec 9;17(12):1614-1624. doi: 10.1016/j.str.2009.09.014.
Recent structural studies have outlined the mechanism of protease inhibition by active site-directed antibodies. However, the molecular basis of allosteric inhibition by antibodies has been elusive. Here we report the 2.35 A resolution structure of the trypsin-like serine protease hepatocyte growth factor activator (HGFA) in complex with the allosteric antibody Ab40, a potent inhibitor of HGFA catalytic activity. The antibody binds at the periphery of the substrate binding cleft and imposes a conformational change on the entire 99-loop (chymotrypsinogen numbering). The altered conformation of the 99-loop is incompatible with substrate binding due to the partial collapse of subsite S2 and the reorganization of subsite S4. Remarkably, a single residue deletion of Ab40 abolished inhibition of HGFA activity, commensurate with the reversal of the 99-loop conformation to its "competent" state. The results define an "allosteric switch" mechanism as the basis of protease inhibition by an allosteric antibody.
最近的结构研究概述了活性位点定向抗体对蛋白酶抑制的机制。然而，抗体变构抑制的分子基础一直难以捉摸。在这里，我们报告了胰蛋白酶样丝氨酸蛋白酶肝细胞生长因子激活剂（HGFA）与变构抗体 Ab40 的 2.35 A 分辨率复合物结构，Ab40 是 HGFA 催化活性的有效抑制剂。该抗体结合在底物结合裂隙的外围，并对整个 99-环（糜蛋白酶原编号）施加构象变化。由于亚基 S2 的部分塌陷和亚基 S4 的重组，99-环的改变构象与底物结合不兼容。值得注意的是，Ab40 的单个残基缺失消除了对 HGFA 活性的抑制，与 99-环构象恢复其“有能力”状态一致。结果定义了“变构开关”机制作为变构抗体抑制蛋白酶的基础。
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