Studies of HIV-1 Gag Protein Assemblies by Solid-State MAS NMR Spectroscopy

Abstract

During virus release from the infected cell, the Pr55Gag polyprotein is cleaved by the viral protease into the major structural Gag proteins of HIV-1. Gag is composed of three major domains: matrix (MA), capsid (CA), and nucleocapsid (NC). Gag also contains two small spacer peptides SP1 and SP2, and a C-terminal p6 domain. When assembled in the presence of RNA, Pr55Gag forms spherical assemblies that are structural analogous to immature virus-like particles (VLPs) 1. In this work we introduce solid state (MAS) NMR spectroscopy to study the structure of assemblies formed by a 40-kDa construct of the Gag polyprotein in which the p6 domain and a 75 amino acid stretch of the MA domain have been removed. This Gag PRR400 construct assembles into well-defined spherical VLPs very similar to those formed by the full-length Gag. The initial results demonstrate the feasibility of high-resolution structural studies of VLP assemblies by MAS NMR. 1. Stephen Campbell, Alan Rein. (1999), Journal of Virology, 73, pp. 2270-2279.