Protease Cleavage Leads to Formation of Mature Trimer Interface in HIV-1 Capsid

• DOI: 10.1371/journal.ppat.1002886
• Publication Date: 2012-08-23T21:35:05Z
• Authors: Xin Meng; Gongpu Zhao; Ernest Yufenyuy; Danxia Ke; Jiying Ning; Maria DeLucia; Jinwoo Ahn; Angela M. Gronenborn; Christopher Aiken; Peijun Zhang
• Keywords: Random hexamer; Cleavage (geology); Trimer

During retrovirus particle maturation, the assembled Gag polyprotein is cleaved by viral protease into matrix (MA), capsid (CA), and nucleocapsid (NC) proteins. To form mature capsid, CA rearranges, resulting in a lattice composed of hexameric pentameric units. Recent structural studies HIV-1 revealed several inter-subunit interfaces lattice, including three-fold interhexamer interface that critical for proper stability. Although general architecture immature particles has been provided cryo-electron tomographic studies, details maturation pathway remain unknown. Here, we used microscopy (cryoEM) to determine structure tubular assemblies CA-SP1-NC protein. Relative structure, observed marked conformational difference position CA-CTD relative NTD assembly, involving flexible hinge connecting two domains. This was verified via engineered disulfide crosslinking, revealing inter-hexamer contacts, particular those at pseudo axis, are altered compared assemblies. Results from crosslinking analyses containing same Cys substitutions protein consistent with these findings. We further show cleavage preassembled vitro leads release SP1 NC without disassembly lattice. Collectively, our results indicate proteolytic reorganization polypeptide creates interface, important formation infectious particles.