A biochemical look into the nucleotide binding site of HIV-1 reverse transcriptase

The HIV-1 reverse transcriptase (RT) is a heterodimer composed of two subun its of 66 and 51 kDa. The polymerase active site resides within the palm su bdomain of the 66-kDa subunit, which bears the catalytic aspartic acid resi dues 110, 185 and 186. The crystal structure of a ternary complex of RT, DN A template-primer and dTTP has shown that several residues (e.g. Lys-GS, Ar g-72, Asp-113, Ala-114, Tyr-115 and Gln-151) interact with the incoming dNT P. The role of these amino acids in polymerase activity, nucleotide specifi city, fidelity of DNA synthesis and resistance to RT inhibitors has been wi dely studied by using recombinant RTs obtained by site-directed mutagenesis . Our studies on the effect in dNTP binding and nucleotide specificity of s ubstituting Tyr-115, Phe-160 or Met-230 are discussed, as well as the biolo gical implications of those substitutions.