Previous Article | Next Article ![]()
Journal of Virology, November 1998, p. 9061-9068, Vol. 72, No. 11
Department of Molecular Microbiology and
Immunology, Johns Hopkins University School of Hygiene and Public
Health, Baltimore, Maryland 21205
Received 11 June 1998/Accepted 13 July 1998
It is unclear whether proteolytic processing of the human
immunodeficiency virus type 1 (HIV-1) Gag protein is dependent on virus
assembly at the plasma membrane. Mutations that prevent myristylation of HIV-1 Gag proteins have been shown to
block virus assembly and release from the plasma membrane of COS cells
but do not prevent processing of Gag proteins. In contrast, in HeLa cells similar mutations abolished processing of Gag proteins as well as
virus production. We have now addressed this issue with CD4+ T cells, which are natural target cells
of HIV-1. In these cells, myristylation of Gag proteins
was required for proteolytic processing of Gag proteins and production
of extracellular viral particles. This result was not due to a lack of
expression of the viral protease in the form of a Gag-Pol precursor or
a lack of interaction between unmyristylated Gag and Gag-Pol
precursors. The processing defect of unmyristylated Gag was partially
rescued ex vivo by coexpression with wild-type
myristylated Gag proteins in HeLa cells. The cell type-dependent
processing of HIV-1 Gag precursors was also observed when another part
of the plasma membrane binding signal, a polybasic region in the matrix
protein, was mutated. The processing of unmyristylated Gag precursors
was inhibited in COS cells by HIV-1 protease inhibitors. Altogether,
our findings demonstrate that the processing of HIV-1 Gag precursors in
CD4+ T cells occurs normally at the plasma membrane during
viral morphogenesis. The intracellular environment of COS
cells presumably allows activation of the viral protease and
proteolytic processing of HIV-1 Gag proteins in the absence of plasma
membrane binding.
0022-538X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
A Bipartite Membrane-Binding Signal in the Human Immunodeficiency
Virus Type 1 Matrix Protein Is Required for the Proteolytic
Processing of Gag Precursors in a Cell Type-Dependent
Manner
*
Corresponding author. Mailing address: Department of
Molecular Microbiology and Immunology, Johns Hopkins University School of Hygiene and Public Health, Room E4012, 615 N. Wolfe St., Baltimore, MD 21205. Phone: (410) 955-3768. Fax: (410) 614-8263. E-mail: xfyu{at}jhsph.edu.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»