structural basis for dual-inhibition mechanism of a non-classical kazal-type serine protease inhibitor from horseshoe crab in complex with subtilisin结构性基础dual-inhibition机制的非经典的kazal-type丝氨酸蛋白酶抑制剂与枯草杆菌蛋白酶从复杂的马蹄蟹.pdf

Structural Basis for Dual-Inhibition Mechanism of a Non-Classical Kazal-Type Serine Protease Inhibitor from Horseshoe Crab in Complex with Subtilisin 1 1,5 3,4 2 1 Rajesh T. Shenoy , Saravanan Thangamani , Adrian Velazquez-Campoy , Bow Ho , Jeak Ling Ding *, J. Sivaraman1* 1 Department of Biological Sciences, National University of Singapore, Singapore, Singapore, 2 Department of Microbiology, National University of Singapore, Singapore, Singapore, 3 Institute of Biocomputation and Physics of Complex Systems (BIFI), Universidad de Zaragoza, Zaragoza, Spain, 4 Fundacion ARAID, Diputacion General de Aragon, Zaragoza, Spain, 5 Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America Abstract Serine proteases play a crucial role in host-pathogen interactions. In the innate immune system of invertebrates, multi- domain protease inhibitors are important for the regulation of host-pathogen interactions and antimicrobial activities. Serine protease inhibitors, 9.3-kDa CrSPI isoforms 1 and 2, have been identified from the hepatopancreas of the horseshoe crab, Carcinoscorpius rotundicauda. The CrSPIs were biochemically active, especially CrSPI-1, which potently inhibited subtilisin (Ki = 1.43 nM). CrSPI has been grouped with the non-classical Kazal-type inhibitors due to its unusual cysteine ˚ distribution. Here we report the crystal structure of CrSPI-1 in complex with subtilisin at 2.6 A resolution and the re