MUTATIONAL ANALYSIS OF RESIDUE-190 OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 REVERSE-TRANSCRIPTASE

S-2720 and other members of the quinoline/quinoxaline class of HIV-1-s pecific nonnucleoside reverse transcriptase inhibitors (NNRTls) select for a glycine to glutamate substitution at residue 190 (Gly 190 Glu) of the reverse transcriptase (RT), when drug-resistant viruses are gen erated in cell culture. This mutation has not been described to appear upon selection for resistant viral variants using derivatives of any other class of NNRTls. Notably, the RNA-dependent DNA polymerase activ ity of the Gly 190 Glu mutant enzyme is drastically diminished with re spect to the wild-type RT. We describe here the effects of other amino acid substitutions at position 190 of the RT that were introduced by using site-directed mutagenesis. Polymerase activities and sensitiviti es to inhibition by a number of NNRTls were determined for the differe nt RT mutants. In general, an inverse correlation was found between th e enzymatic activity and increasing length of the side chain, whereas the size of the residue and the level of resistance to NNRTls appeared to be positively related. Double mutants, which contain the Gly 190 G lu mutation together with substitutions that confer resistance to othe r RT inhibitors, were all shown to possess severely diminished polymer ase activity. (C) 1994 Academic Press, Inc.