Nucleotide-dependent conformational change governs specificity and analog discrimination by HIV reverse transcriptase.

ABSTRACT: Single turnover studies on HIV reverse transcriptase suggest that nucleoside analogs bind more tightly to the enzyme than normal substrates, contrary to rational structural predictions. Here we resolve these controversies by monitoring the kinetics of nucleotide-induced changes in enzyme structure. We show that the specificity constant for incorporation of a normal nucleotide (dCTP) is determined solely by the rate of binding (including isomerization) because isomerization to the closed complex commits the substrate to react. In contrast, a nucleoside analog (3TC-TP, triphosphate form of lamivudine) is incorporated slowly, allowing the conformational change to come to equilibrium and revealing tight nucleotide binding. Our data reconcile previously conflicting reports suggesting that nucle

SUBMITTER: Kellinger MW 

PROVIDER: S-EPMC2867896 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature