Active human immunodeficiency virus protease is required for viral infectivity.

Abstract

Retroviral proteins are synthesized as polyprotein precursors that undergo proteolytic cleavages to yield the mature viral proteins. The role of the human immunodeficiency virus (HIV) protease in the viral replication cycle was examined by use of a site-directed mutation in the protease gene. The HIV protease gene product was expressed in Escherichia coHl and observed to cleave HIV gag p55 to gag p24 and gag p17 in vitro. Substitution of aspartic acid residue 25 (Asp-25) of this protein with an asparagine residue did not affect the expression of the protein, but it eliminated detectable in vitro proteolytic activity against HIV gag p55. A mutant HIV provirus was constructed that contained the Asn-25 mutation within the protease gene. SW480 human colon carcinoma cells transfected with the Asn-25 mutant proviral DNA produced virions that contained gag p55 but not gag p24, whereas virions from cells transfected with the wild-type DNA contained both gag p55 and gag p24. The mutant virions were not able to infect MT-4 lymphoid cells. In contrast, these cells were highly sensitive to infection by the wild-type virions. These results demonstrate that the HIV protease is an essential viral enzyme and, consequently, an attractive target for anti-HIV drugs.

Three‐dimensional solution structure of the HIV‐1 protease complexed with DMP323, a novel cyclic urea‐type inhibitor, determined by nuclear magnetic resonance spectroscopy

“…Structural proteins and enzymes that are essential to the life cycle of the HIV virus are products of the enzymatic cleavage of the polyprotein products of the gag and pol viral genes (Kohl et al, 1988;Seelmeier et al, 1988). The enzyme responsible for the cleavage reactions is the HIV aspartyl protease, and inhibition of this protease leads to the production of noninfectious viral particles.…”

Synthetic “interface” peptides alter dimeric assembly of the HIV 1 and 2 proteases

“…Dimerization and activation of the retroviral PRs is presumably concentration dependent and therefore likely to occur once viral capsid assembly has begun increasing the colocalization of viral proteins. Inhibition of this dimerization step would prevent the activation of the viral PR and, in turn, prevent the polyprotein processing, which is essential for viral maturation and infectivity (Kohl et al, 1988). The ability of oligopeptides to interfere with formation of a protein complex has been previously documented in vitro for two herpes simplex virus systems, the enzyme ribonucleotide reductase (Dutia et al, 1986;McClements et al, 1988), and the regulatory protein VP16 (Haigh et al, 1990).…”

HIV-1 proprotein processing as a target for gene therapy

“…Excision of individual enzymes and structural proteins is felt to be performed by the aspartyl protease, HIV-1 PR, and largely occurs in budding virions. 21 Unexpectedly, Western blot analyses showed that SV(AT) inhibited processing of p55 Gag in SupT1 cells and in primary human lymphocytes; high levels of uncleaved p55 Gag protein accumulated within cells and were detected in virus particle progeny recovered from these cells after transduction with SV(AT).…”

“…21 Just as cellular serine protease activity is fundamentally important to envelope, viral aspartyl protease activity is required for gag proprotein processing: both processes are necessary to generate infectious viral progeny. 19,22 Thus, gene delivery to inhibit proteolytic cleavage of envelope and gag precursors could represent a new approach for gene therapy to interfere with HIV-1 infectivity.…”