Stabilization of Moloney murine leukemia virus reverse transcriptase by site-directed mutagenesis of surface residue Val433

After thermal incubation at 48 °C for 10 min, single variants of Moloney murine leukemia virus reverse transcriptase, V433R and V433K in which a surface hydrophobic residue, Val433, was mutated, retained 55% of initial reverse transcription activity, while the wild-type enzyme retained 17%. After thermal incubation at 50 °C for 10 min, multiple variants D108R/E286R/V433R and D108R/E286R/V433R/D524A, in which Val433→Arg was combined with stabilizing mutations we identified previously, Asp108→Arg and Glu286→Arg, and RNase H activity-eliminating mutation Asp524→Ala, retained 70% of initial activity, exhibiting higher stability than V433R or V433K.