Proteinases of betaretroviruses bind single-stranded nucleic acids through a novel interaction module, the G-patch.

Retroviral proteinases (PRs) are essential for retrovirus infectivity but the mechanism of their activity regulation is poorly understood. We investigated possible involvement in this process of the C-terminal domain (CTD) of betaretroviral PRs. We found that the presence of CTD attenuates proteolytic activity of Mason-Pfizer monkey virus PR, while it does not significantly affect the activity of mouse intracisternal A-particle retrovirus PR. However, both PRs bind single-stranded nucleic acids through their CTDs that contain a novel binding motif, the G-patch, whose function is dependent on a single conserved tyrosine residue. Oligonucleotide binding to both PRs does not inhibit their proteolytic activity. Copyright 2004 Federation of European Biochemical Societies