title: Human immunodeficiency virus type 1 capsid protein is a substrate of the retroviral proteinase while integrase is resistant toward proteolysis.
abstract: The capsid protein of human immunodeficiency virus type 1 was observed to undergo proteolytic cleavage in vitro when viral lysate was incubated in the presence of dithiothreitol at acidic pH. Purified HIV-1 capsid protein was also found to be a substrate of the viral proteinase in a pH-dependent manner; acidic pH (<7) was necessary for cleavage, and decreasing the pH toward 4 increased the degree of processing. Based on N-terminal sequencing of the cleavage products, the capsid protein was found to be cleaved at two sites, between residues 77 and 78 as well as between residues 189 and 190. Oligopeptides representing these cleavage sites were also cleaved at the expected peptide bonds. The presence of cyclophilin A decreased the degree of capsid protein processing. Unlike the capsid protein, integrase was found to be resistant toward proteolysis in good agreement with its presence in the preintegration complex.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Debrecen, Faculty of Medicine, H-4012 Debrecen, Hungary. tozser@indi.biochem.dote.hu
authors.forename: József
authors.initials: J
authors.lastname: Tözsér
authors.forename: Sergey
authors.initials: S
authors.lastname: Shulenin
authors.forename: János
authors.initials: J
authors.lastname: Kádas
authors.forename: Péter
authors.initials: P
authors.lastname: Boross
authors.forename: Péter
authors.initials: P
authors.lastname: Bagossi
authors.forename: Terry D
authors.initials: TD
authors.lastname: Copeland
authors.forename: Bala C
authors.initials: BC
authors.lastname: Nair
authors.forename: Mangalasseril G
authors.initials: MG
authors.lastname: Sarngadharan
authors.forename: Stephen
authors.initials: S
authors.lastname: Oroszlan
mesh_terms: D036022:Capsid Proteins / Q000378:metabolism*; D021984:Cyclophilin A / Q000494:pharmacology; D019427:HIV Integrase / Q000378:metabolism*; D016333:HIV Protease / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration
chemical_list: D036022:Capsid Proteins; D019427:HIV Integrase; D016333:HIV Protease; D021984:Cyclophilin A