Structures of the Middle East respiratory syndrome coronavirus 3C-like protease reveal insights into substrate specificity.
Structures of the Middle East respiratory syndrome coronavirus 3C-like protease reveal insights into substrate specificity.
复制标题
中东呼吸综合征3C样蛋白酶的结构揭示了对底物特异性的见解。
DOI：
10.1107/s1399004715003521
复制
发表时间：
2015-05
期刊：
影响因子：
--
通讯作者：
Waugh DS
中科院分区：
文献类型：
--
作者：
Needle D;Lountos GT;Waugh DS
中东呼吸综合征冠状病毒（MERS-CoV）是一种高致病性病毒，可引起严重呼吸道疾病，伴有多器官功能障碍，导致病死率约为40%。与其他冠状病毒一样，MERS-CoV基因组的大部分正链RNA被翻译成两种多聚蛋白，一种是由核糖体移码产生的，它们在三个位点被木瓜蛋白酶样蛋白酶切割，在11个位点被3C样蛋白酶（3CLpro）切割。由于3CLpro对病毒复制至关重要，因此它是治疗干预的主要候选者。为了加速3CLpro抑制剂的开发，确定了MERS-CoV 3CLpro酶的无催化活性变体（C148 A）的三种晶体结构。目的是使无活性的酶与肽底物共结晶。然而，偶然的是，在两个结构中，一个原聚体的C末端结合在相邻分子的活性位点中，提供了酶-产物复合物的快照。在第三种结构中，不对称单元中的三个原聚体中的两个形成了类似于SARS-CoV 3CLpro的同源二聚体;然而，第三个原聚体采用了完全不同的构象，可能对应于晶体学单体，这表明酶具有很大的结构可塑性。本研究结果为MERS-CoV 3CLpro酶的小分子抑制剂的结构设计提供了基础。
Middle East respiratory syndrome coronavirus (MERS‐CoV) is a highly pathogenic virus that causes severe respiratory illness accompanied by multi‐organ dysfunction, resulting in a case fatality rate of approximately 40%. As found in other coronaviruses, the majority of the positive‐stranded RNA MERS‐CoV genome is translated into two polyproteins, one created by a ribosomal frameshift, that are cleaved at three sites by a papain‐like protease and at 11 sites by a 3C‐like protease (3CLpro). Since 3CLpro is essential for viral replication, it is a leading candidate for therapeutic intervention. To accelerate the development of 3CLpro inhibitors, three crystal structures of a catalytically inactive variant (C148A) of the MERS‐CoV 3CLpro enzyme were determined. The aim was to co‐crystallize the inactive enzyme with a peptide substrate. Fortuitously, however, in two of the structures the C‐terminus of one protomer is bound in the active site of a neighboring molecule, providing a snapshot of an enzyme–product complex. In the third structure, two of the three protomers in the asymmetric unit form a homodimer similar to that of SARS‐CoV 3CLpro; however, the third protomer adopts a radically different conformation that is likely to correspond to a crystallographic monomer, indicative of substantial structural plasticity in the enzyme. The results presented here provide a foundation for the structure‐based design of small‐molecule inhibitors of the MERS‐CoV 3CLpro enzyme.