title: Three active forms of aspartic proteinase from Mason-Pfizer monkey virus.
abstract: Mason-Pfizer monkey virus (M-PMV) proteinase, released by the autocatalytic cleavage of Gag-Pro and Gag-Pro-Pol polypeptide precursors, catalyzes the processing of viral precursors to yield the structural proteins and enzymes of the virion. In retroviruses, usually only one proteolytically active form of proteinase exists. Here, we describe an unusual feature of M-PMV, the existence of three active forms of a retroviral proteinase with molecular masses of 17, 13, and 12 kDa as determined by mass spectroscopy. These forms arise in vitro by self-processing of a 26-kDa proteinase precursor. We have developed a process for isolation of each truncated product and demonstrate that all three forms display proteolytic activity. Amino acid analyses, as well as the determination of N- and C-terminal sequences, revealed that the N-termini of all three forms are identical, confirming that in vitro autoprocessing of the 17-kDa form occurs at the C-terminus to yield the truncated forms. The 17-kDa form and the newly described 13-kDa form of proteinase were identified in virions collected from the rhesus monkey CMMT cell line chronically infected with M-PMV, confirming that multiple forms exist in vivo.
authors.affiliation: Department of Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: A
authors.initials: A
authors.lastname: Zábranský
authors.forename: M
authors.initials: M
authors.lastname: Andreánsky
authors.forename: O
authors.initials: O
authors.lastname: Hrusková-Heidingsfeldová
authors.forename: V
authors.initials: V
authors.lastname: Havlícek
authors.forename: E
authors.initials: E
authors.lastname: Hunter
authors.forename: T
authors.initials: T
authors.lastname: Ruml
authors.forename: I
authors.initials: I
authors.lastname: Pichová
mesh_terms: D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000032:analysis* / Q000378:metabolism; D004789:Enzyme Activation; D000882:Haplorhini; D016093:Mason-Pfizer monkey virus / Q000201:enzymology*; D013058:Mass Spectrometry; D013379:Substrate Specificity; D014764:Viral Proteins / Q000032:analysis* / Q000378:metabolism
chemical_list: D014764:Viral Proteins; D016282:Aspartic Acid Endopeptidases