Increased polymerase fidelity of E89G, a nucleoside analog-resistant variant of human immunodeficiency virus type 1 reverse transcriptase

Nucleoside analog resistance in human immunodeficiency virus type I results from mutations in reverse transcriptase (RT) that allow the enzyme to discriminate against such analogs. To evaluate the possible impact of such mutations on the ability of human immunodeficiency virus RT to selectively incorporate Watson-Crick base-paired deoxynucleotide triphosphates (dNTPs) over incorrectly paired dNTPs, we have measured the fidelity of dNTP insertion by the E89G variant of RT in in vitro reaction mixtures containing synthetic template primers. The E89G RT was previously shown to be resistant to several ddNTPs and to phosphonoformic acid. Our results show that the mutant enzyme displays a lower level of efficiency of misinsertion than did the wild-type RT for every mispair tested (ranging from 2- to 17-fold).