Mason-Pfizer monkey virus protease (PR) was crystallized in complex with two pepstatin-based inhibitors in P1 space group. In both crystal structures, the extended flap loops that lock the inhibitor/substrate over the active site, are visible in the electron density either completely or with only small gaps, providing the first observation of the conformation of the flap loops in dimeric complex form of this retropepsin. The H-bond network in the active site (with D26N mutation) differs from that reported for the P21 crystal structures and is similar to a rarely occurring system in HIV-1 PR.

• Keywords
• M-PMV, Mason-Pfizer monkey virus, active site architecture, aspartic protease, dimer, flap structure, inhibitor, retropepsin, retrovirus,
• MeSH
• Protease Inhibitors chemistry   MeSH
• Mason-Pfizer monkey virus enzymology   genetics   MeSH
• Mutation, Missense MeSH
• Pepstatins chemistry   MeSH
• Peptide Hydrolases chemistry   genetics   MeSH
• Protein Structure, Secondary MeSH
• Amino Acid Substitution MeSH
• Viral Proteins antagonists & inhibitors   chemistry   genetics   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Protease Inhibitors MeSH
• pepstatin MeSH Browser
• Pepstatins MeSH
• Peptide Hydrolases MeSH
• Viral Proteins MeSH

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.

• MeSH
• Cell Line MeSH
• Humans MeSH
• Mason-Pfizer monkey virus chemistry   enzymology   genetics   MeSH
• Polyproteins chemistry   genetics   metabolism   MeSH
• RNA-Directed DNA Polymerase chemistry   genetics   metabolism   MeSH
• Protein Structure, Tertiary MeSH
• Viral Proteins chemistry   genetics   metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Polyproteins MeSH
• RNA-Directed DNA Polymerase MeSH
• Viral Proteins MeSH