Role of the gag and pol genes of human immunodeficiency virus in the morphogenesis and maturation of retrovirus-like particles expressed by recombinant vaccinia virus: an ultrastructural study

Comparative Morphology of Gag Protein Structures Produced by Mutants of the gag Gene of Human Immunodeficiency Virus Type 1

“…G6ttlinger et al (1991) have reported that deletion of Pr6 prevented the release of particles from the host cell membrane. In the majority of similar studies, however, deletion of the Pr6 domain has not prevented particle release (Hoshikawa et al, 1991;Royer et at., 1991;Jowett et al, 1992) which indicates a possible co-factor-dependent role for the Pr6 domain in the fina| stages of budding. The Gag Pr7 domain is required for the capture and incorporation of RNA into the budding particle (Gorelick et al, 1990;Clavel & Orenstein, 1990) but deletion of much of Pr7 does not prevent particle formation (Royer et al, 1991;Jowett et al, 1992).…”

“…At the amino (N) terminus of Gag, myristylation of the N-terminal glycine in association with a distinct MA-encoded sequence is required for transport of the protein to the host cell plasma membrane (Gheysen et al, 1989;G6ttlinger et al, 1989;Overton et al, 1989;Royer et al, 1991;Yuan et al, 1993). Deletion of the entire Prl5 NC domain from the carboxy (C) terminus of the Gag precursor molecule has no effect on membrane targeting but abolishes particle formation (Gheysen et al, 1989;Hoshikawa et al, 1991) whereas shorter deletions within the NC domain have been reported variously to affect particle assembly and release. G6ttlinger et al (1991) have reported that deletion of Pr6 prevented the release of particles from the host cell membrane.…”

Gag-Gag interactions in the C-terminal domain of human immunodeficiency virus type 1 p24 capsid antigen are essential for Gag particle assembly

“…Recent evidence has located a discrete assembly signal in the MA domain (Freed et al, 1994;Chazal et al, 1995) and has also defined the functional basis of failure to assemble particles as an inability of Gag molecules to oligomerize (Morikawa et al, 1995). The majority of the NC domain appears not to be involved in Gag particle assembly although a role for a short SP1 peptide sequence at the CA/NC junction has been reported (Jowett et al, 1992;Hoshikawa et al, 1991 ;Pettit et al, 1994;Chazal et al, 1995;Krausslich et al, 1995), and the C-terminal protein p6 has an auxiliary role in efficient particle release from the cell and in recruiting Vpr into the budding virion (Paxton et al, 1993;Gottlinger et al, 1991). That sequences in the CA domain are essential for assembly was first indicated by the observations that Gag molecules with deletions in CA are defective in assembly and exhibit trans-dominance in complementation experiments (Trono et al, 1989).…”

“…This event results from cleavage of the Gag precursor by viral proteinase into the mature Gag proteins, matrix protein (MA, p17), capsid protein (CA, p24), the nucleocapsid protein (NC, p9) and a proline rich protein (p6) (Wills & Craven, 1991 ;Veronese et al, 1988;Kaplan et al, 1994). Expression of Gag Pr55 in the absence of the HIV proteinase results in the release of Gag virus like particles (VLP) and this system has provided a basis for experimental analysis of the requirements for particle assembly and release (Gheysen et al, 1989;Overton et al, 1989;Hu et al, 1990;Hoshikawa et al, 1991 ;Royer et at., 1991 ;Jowett et aL, 1992;Mergener et al, 1992). * Author for correspondence.…”

Human Immunodeficiency Virus Type 1 Gag Assembly through Assembly Intermediates

“…The major structural component of human immunodeficiency virus (HIV), 1 Gag, is the sole protein required for viral particle budding, and expression of Gag protein alone in eukaryotic cells produces Gag virus-like particle (VLP), morphologically identical to the immature form of HIV particles (1)(2)(3). The process of Gag assembly is thought to consist of N-terminal myristoylation of Gag followed by relocation to the plasma membrane and multimerization of Gag to form VLP.…”