Structural characterization of HIV-1 matrix mutants implicated in envelope incorporation.

Autor:	Eastep GN; Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA., Ghanam RH; Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA., Green TJ; Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA., Saad JS; Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA. Electronic address: saad@uab.edu.
Jazyk:	angličtina
Zdroj:	The Journal of biological chemistry [J Biol Chem] 2021 Jan-Jun; Vol. 296, pp. 100321. Date of Electronic Publication: 2021 Jan 22.
DOI:	10.1016/j.jbc.2021.100321
Abstrakt:	During the late phase of HIV-1 infection, viral Gag polyproteins are targeted to the plasma membrane (PM) for assembly. Gag localization at the PM is a prerequisite for the incorporation of the envelope protein (Env) into budding particles. Gag assembly and Env incorporation are mediated by the N-terminal myristoylated matrix (MA) domain of Gag. Nonconservative mutations in the trimer interface of MA (A45E, T70R, and L75G) were found to impair Env incorporation and infectivity, leading to the hypothesis that MA trimerization is an obligatory step for Env incorporation. Conversely, Env incorporation can be rescued by a compensatory mutation in the MA trimer interface (Q63R). The impact of these MA mutations on the structure and trimerization properties of MA is not known. In this study, we employed NMR spectroscopy, X-ray crystallography, and sedimentation techniques to characterize the structure and trimerization properties of HIV-1 MA A45E, Q63R, T70R, and L75G mutant proteins. NMR data revealed that these point mutations did not alter the overall structure and folding of MA but caused minor structural perturbations in the trimer interface. Analytical ultracentrifugation data indicated that mutations had a minimal effect on the MA monomer-trimer equilibrium. The high-resolution X-ray structure of the unmyristoylated MA Q63R protein revealed hydrogen bonding between the side chains of adjacent Arg-63 and Ser-67 on neighboring MA molecules, providing the first structural evidence for an additional intermolecular interaction in the trimer interface. These findings advance our knowledge of the interplay of MA trimerization and Env incorporation into HIV-1 particles. Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article. (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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