Mutational analysis of HIV-2 Vpx shows that proline residue 109 in the poly-proline motif regulates degradation of SAMHD1.

In this study, we performed a mutational analysis to determine whether the mechanism by which HIV-2 Vpx confers the capacity for infectivity and viral replication in macrophages is solely dependent on its ability to degrade the host antiviral factor SAMHD1. Contrary to expectations, we demonstrated that P(109) in the C-terminal poly-proline motif of HIV-2 Vpx has two unique roles: to facilitate the specific degradation of SAMHD1 in macrophages, and to facilitate multimerization of Vpx, therefore preventing SAMHD1 degradation in the presence of high levels of Vpx.