title: The G-patch domain of Mason-Pfizer monkey virus is a part of reverse transcriptase.
abstract: Mason-Pfizer monkey virus (M-PMV), like some other betaretroviruses, encodes a G-patch domain (GPD). This glycine-rich domain, which has been predicted to be an RNA binding module, is invariably localized at the 3' end of the pro gene upstream of the pro-pol ribosomal frameshift sequence of genomic RNAs of betaretroviruses. Following two ribosomal frameshift events and the translation of viral mRNA, the GPD is present in both Gag-Pro and Gag-Pro-Pol polyproteins. During the maturation of the Gag-Pro polyprotein, the GPD transiently remains a C-terminal part of the protease (PR), from which it is then detached by PR itself. The destiny of the Gag-Pro-Pol-encoded GPD remains to be determined. The function of the GPD in the retroviral life cycle is unknown. To elucidate the role of the GPD in the M-PMV replication cycle, alanine-scanning mutational analysis of its most highly conserved residues was performed. A series of individual mutations as well as the deletion of the entire GPD had no effect on M-PMV assembly, polyprotein processing, and RNA incorporation. However, a reduction of the reverse transcriptase (RT) activity, resulting in a drop in M-PMV infectivity, was determined for all GPD mutants. Immunoprecipitation experiments suggested that the GPD is a part of RT and participates in its function. These data indicate that the M-PMV GPD functions as a part of reverse transcriptase rather than protease.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, vvi, IOCB & Gilead Research Center, Prague, Czech Republic.
authors.forename: Ivana
authors.initials: I
authors.lastname: Křízová
authors.forename: Romana
authors.initials: R
authors.lastname: Hadravová
authors.forename: Jitka
authors.initials: J
authors.lastname: Štokrová
authors.forename: Jana
authors.initials: J
authors.lastname: Günterová
authors.forename: Michal
authors.initials: M
authors.lastname: Doležal
authors.forename: Tomáš
authors.initials: T
authors.lastname: Ruml
authors.forename: Michaela
authors.initials: M
authors.lastname: Rumlová
authors.forename: Iva
authors.initials: I
authors.lastname: Pichová
mesh_terms: D000818:Animals; D002460:Cell Line; D006801:Humans; D016093:Mason-Pfizer monkey virus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D020815:Polyproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012194:RNA-Directed DNA Polymerase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D020815:Polyproteins; D014764:Viral Proteins; D012194:RNA-Directed DNA Polymerase