SUBUNIT-SPECIFIC MUTAGENESIS OF THE CYSTEINE-280 RESIDUE OF THE REVERSE-TRANSCRIPTASE OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 - EFFECTS ON SENSITIVITY TO A SPECIFIC INHIBITOR OF THE RNASE-H ACTIVITY

Treatment of human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) with N-ethylmaleimide (NEM) selectively inhibits the RNase H activity, The cysteine residue at position 280 (C280) is the target for NEM; HIV-1 RT carrying the mutation C280S is resistant to NEM. Si nce HIV-1 RT is composed of two related subunits (p66 and p51) that pl ay distinct roles, me asked whether the C280 in p51 or the C280 in p66 is responsible for the sensitivity of the enzyme to NEM, HIV-1 RT ver sions were prepared that had one mutant and one wild-type subunit. Whe n these chimeric enzymes were tested, both the p51 and p66 subunits we re found to contribute to the sensitivity of the enzyme to NEM. The im plications of these results are discussed in the context of the struct ure of the enzyme.