ENZYMATIC-PROPERTIES AND SENSITIVITY TO INHIBITORS OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 (HIV-1) REVERSE-TRANSCRIPTASE WITH GLU-138-]ARG AND TYR-188-]HIS MUTATIONS

Two mutants of HIV-1 reverse transcriptase (RT), Tyr-188-->His and Glu -138-->Arg have been prepared and their catalytic properties and sensi tivities to inhibitors studied. As compared to wild type RT, a reducti on in catalytic efficiency and turn over number was observed, especial ly for the Tyr-188-->His mutant. The non-nucleoside inhibitors nevirap ine, L-697,661 and 9-Cl-TIBO caused a mixed type of inhibition of RT ( Arg-138) with respect to substrate, and with the exception of a non-co mpetitive inhibition by nevirapine, also a mixed type of inhibition of RT (His-188). Foscarnet (PFA) caused a non-competitive type of inhibi tion of RT (Arg-138) and a mixed inhibition of RT (His-188). The inhib ition by ddG-TP was competitive with both mutant RTs. Inhibition by ne virapine gave IC50 values of 0.15, 0.23 and 0.72 mu M; by 9-Cl-TIBO of 0.20, 2.50 and 10.3 mu M; by L-697,661 of 0.064, 0.28 and 0.60 mu M; by ddGTP of 0.13, 0.14 and 0.02 mu M; by PFA of 17.0, 48.0 and 15.0 mu M for RT wt, RT (Arg-138) and RT (His-188), respectively.