title: Comparison of human immunodeficiency virus type 1 Pr55(Gag) and Pr160(Gag-pol) processing intermediates that accumulate in primary and transformed cells treated with peptidic and nonpeptidic protease inhibitors.
abstract: Human immunodeficiency virus type 1 (HIV-1) produces two polyproteins, Pr55(Gag) and Pr160(Gag-Pol), that are cleaved into mature functional subunits by the virally encoded protease. Drugs that inhibit this protease are an important part of anti-HIV therapy. We studied the ordered accumulation of Gag and Gag-Pol processing intermediates by variably blocking the protease with HIV-1 protease inhibitors (PIs). Variable protease inhibition caused accumulation of a complex pattern of processing intermediates, which was the same after incubating HIV-1-infected cells with increasing concentrations of either one of the peptidomimetic inhibitors indinavir, saquinavir (SQV), ritonavir (RTV), nelfinavir, and SC-52151 or one of the nonpeptidomimetic inhibitors DMP450, DMP323, PNU-140135, and PNU-109112 for 3 days. The patterns of Gag and Gag-Pol processing intermediate accumulation were nearly identical when the following were compared: cell- versus virion-associated proteins, HIV-1-infected transformed cell lines versus primary human peripheral blood mononuclear cells (PBMCs) and HIV-1(MN) versus HIV-1(IIIB) virus strains. RTV was a more potent inhibitor of p24 production in PBMCs than SQV by approximately 7-fold, whereas SQV was a more potent inhibitor in transformed cells than RTV by approximately 30-fold. Although the antiretroviral potency of HIV-1 PIs may change as a function of cell type, the polyprotein intermediates that accumulate with increasing drug concentrations are the same. These results support sequential processing of Gag and Gag-Pol polyproteins by the HIV-1 protease and may have important implications for understanding common cross-resistance pathways.
authors.affiliation: Departments of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-5554, USA.
authors.forename: R R
authors.initials: RR
authors.lastname: Speck
authors.forename: C
authors.initials: C
authors.lastname: Flexner
authors.forename: C J
authors.initials: CJ
authors.lastname: Tian
authors.forename: X F
authors.initials: XF
authors.lastname: Yu
mesh_terms: D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D015683:Gene Products, gag / Q000378:metabolism*; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D054301:gag Gene Products, Human Immunodeficiency Virus; D054302:pol Gene Products, Human Immunodeficiency Virus
chemical_list: D015683:Gene Products, gag; D017320:HIV Protease Inhibitors; D011498:Protein Precursors; D054301:gag Gene Products, Human Immunodeficiency Virus; C059767:p55 gag precursor protein, Human immunodeficiency virus 1; D054302:pol Gene Products, Human Immunodeficiency Virus; C091950:pr160 gag-pol precursor protein, Human immunodeficiency virus 1