Structural basis for the specificity of renin-mediated angiotensinogen cleavage
Structural basis for the specificity of renin-mediated angiotensinogen cleavage
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肾素介导的血管紧张素原裂解特异性的结构基础。
DOI：
10.1074/jbc.ra118.006608
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发表时间：
2019-02-15
影响因子：
4.8
通讯作者：
Read, Randy J.
中科院分区：
文献类型：
--
作者：
Yan, Yahui;Zhou, Aiwu;Read, Randy J.
肾素-血管紧张素级联反应是一种调节血压和体液平衡的激素系统。血管紧张素原（AGT）N末端的血管紧张素I肽的肾素介导的切割是该级联反应的限速步骤;然而，该步骤的详细分子机制尚不清楚。在这里，我们解析了糖基化的人AGT（2.30 A分辨率）、其与肾素的遭遇复合物（2.55 A）、在其反应中心环中裂解的AGT（RCL; 2.97 A）和从中除去N-末端血管紧张素肽的消耗AGT（2.63 A）的晶体结构。这些结构表明，AGT经历了深刻的构象变化，并通过尾入口变构机制，插入到一个口袋相当于其他丝氨酸蛋白酶抑制剂的酶结合位点的N末端结合肾素。这些变化完全延长了N-末端尾部，血管紧张素释放的易断键停靠在肾素的活性位点。插入到这个口袋中的N末端伴随着AGT的螺旋H的完全解旋，这反过来又形成了与互补结合界面中的肾素的关键相互作用。突变和动力学分析证实，肾素介导的血管紧张素I的产生是由氨基酸残基和聚糖组分的相互作用控制的肾素的活性位点裂缝外。我们的研究结果表明，AGT适应独特的丝氨酸蛋白酶抑制剂功能的激素输送和结合肾素通过协调一致的运动在N-末端的尾巴，并在其主体调节血管紧张素释放。这些见解为开发通过靶向AGT的激素结合口袋来减弱血管紧张素释放的药物提供了结构基础。
The renin-angiotensin cascade is a hormone system that regulates blood pressure and fluid balance. Renin-mediated cleavage of the angiotensin I peptide from the N terminus of angiotensinogen (AGT) is the rate-limiting step of this cascade; however, the detailed molecular mechanism underlying this step is unclear. Here, we solved the crystal structures of glycosylated human AGT (2.30 A resolution), its encounter complex with renin (2.55 A), AGT cleaved in its reactive center loop (RCL; 2.97 A), and spent AGT from which the N-terminal angiotensin peptide was removed (2.63 A). These structures revealed that AGT undergoes profound conformational changes and binds renin through a tail-into-mouth allosteric mechanism that inserts the N terminus into a pocket equivalent to a hormone-binding site on other serpins. These changes fully extended the N-terminal tail, with the scissile bond for angiotensin release docked in renin's active site. Insertion of the N terminus into this pocket accompanied a complete unwinding of helix H of AGT, which, in turn, formed key interactions with renin in the complementary binding interface. Mutagenesis and kinetic analyses confirmed that renin-mediated production of angiotensin I is controlled by interactions of amino acid residues and glycan components outside renin's active-site cleft. Our findings indicate that AGT adapts unique serpin features for hormone delivery and binds renin through concerted movements in the N-terminal tail and in its main body to modulate angiotensin release. These insights provide a structural basis for the development of agents that attenuate angiotensin release by targeting AGT's hormone binding pocket.