Mutagenesis of Gln294 of the reverse transcriptase of human immunodeficiency virus type-2 and its effects on the ribonuclease H activity

Abstract 

Despite the high homology between human immunodeficiency virus type-1 (HIV-1) and human immunodeficiency virus type-2 (HIV-2) reverse transcriptases (RTs), the ribonuclease H (RNase H) level of HIV-2 RT is lower than that of HIV-1 RT, while the DNA polymerase of both RTs is similar. We conducted mutagenesis of HIV-2 RT Gln294 (shown to control the RNase H activity level when modified to a Pro in the smaller p54 subunit and not in the larger p68 subunit) to various residues, and assayed the activities of all mutants. All exhibited an RNase H that is higher than the wild-type (WT) HIV-2 RT level, although the DNA polymerase of all mutants equals WT HIV-2 RT level. These results represent a unique case, where every mutation induces an increase rather than a decrease in an enzyme’s activity.

Abbreviations: RT, reverse transcriptase, HIV-1, human immunodeficiency virus type-1, HIV-2, human immunodeficiency virus type-2, RNase H, ribonuclease H, AIDS, acquired immunodeficiency syndrome, WT, wild-type, IPTG, isopropyl β-thiogalactopyranoside

Keywords: Reverse transcriptase, Ribonuclease H, HIV-2, HIV-1, Mutagenesis of Gln294