Interaction Between Vpx and SAMHD1, Vital for SAMHD1 Inhibition.

It was confirmed that the sterile alpha motif and HD domain 1 (SAMHD1) limits human immunodeficiency virus type 1 (HIV-1) replication. In contrast, viral protein x (Vpx) in HIV-2 and some simian immunodeficiency viruses can counteract this effect. The possible interaction between SAMHD1 and Vpx was suggested by previous studies; however, there are no data to confirm this interaction. Therefore, this study aimed to study the interaction between two proteins and the properties of Vpx protein for the first time using bioinformatic tools. Vpx and SAMHD1 sequences were obtained from the National Center for Biotechnology Information GenBank. Several software were used to define Vpx properties and the interaction between Vpx and different SAMHD1 isoforms. Our findings indicated the difference in interaction sites among different Vpx. However, in all Vpx proteins, this region is from amino acids 4 to 90. In addition, two regions (26-31 and 134-139) and two amino acids 425 and 429 in SAMHD1 are vital in the possible interaction. In addition, our analysis determined the physicochemical and immunological properties of the Vpx. Considering all factors, this study could confirm that Vpx interacts with SAMHD1, which could inhibit SAMHD1. Moreover, our findings can pave the way for future studies to express and purify Vpx in the laboratory and study this protein in vitro.