Effects of mutations in an HIV‐1 gag gene containing a 107‐codon tandem repeat in the matrix region on assembly and processing of the protein product

Abstract

It has been demonstrated previously that a human immunodeficiency virus (HIV) type 1 Gag mutant (MA2) with a tandem repeat of 107-matrix codons in the matrix domain could direct virus particle assembly and budding [Wang et al. (2000c): J Med Virol 61:423-432]. Since the regions involved functionally in HIV Gag assembly and transport have been mapped to the matrix domain, it was interesting to test the effects of the duplicated matrix-coding sequence on Gag assembly, transport, and virus processing of some assembly-defective HIV matrix mutants. In this study, a number of HIV matrix mutations were introduced into either the proximal or distal copy of the duplicated matrix-coding sequence. Assembly, release, processing, and subcellular localization of the Gag mutants were analyzed by transient expression in 293T cells. The result indicates that the budding defect of HIV matrix mutants could be moderately or significantly reversed when the additional 107-matrix codons were present; however, these matrix double mutations affected significantly the virus particle processing. Mislocalized matrix mutants could also be redistributed to a certain degree in the presence of the duplicated matrix copy. Although the subcellular distribution patterns of the matrix mutants did not correlate completely with the budding efficiency, the data suggest that the budding defect caused by the matrix mutations could be masked to some extent by the duplicated matrix coding sequence.

Analysis of human immunodeficiency virus matrix domain replacements

“…Previous reports have demonstrated that while the globular head of HIV-1 MA can exert a negative effect on virus assembly in some cellular contexts (Hatziioannou et al, 2005;Hubner and Chen, 2006;Perez-Caballero et al, 2004), large sequence insertions into MA can be accommodated for the purposes of VLP assembly and release (Liao et al, 2004;Muller et al, 2004;Wang et al, 2000). Moreover, matrix domain swapping studies have revealed that some chimeric retrovirus PrGag proteins efficiently assemble virions that can be infectious (Chen et al, 2001;Reed et al, 2002).…”