Structure-activity Relationships of Hiv-1 Reverse Transcriptase

National Institute Of Environmental Health Sciences

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Abstract

SUMMARY OF WORK: Through studies of the HIV-1 reverse transcriptase (RT) mechanism, our laboratory in collaboration with others, discovered that mutation propensity during viral replication is linked to how strongly the enzyme stays attached to the viral nucleic acid template during replication. Thus, if RT falls off the viral template during replication, RT tends to make an error (or mutation) at the point where it re-initiates replication on the template. This mechanism appears to account for a portion of the HIV-1 genetic hypervariability. Much insight into the mechanism of template dissociation has been gained by combining structural information on RT with biochemical studies of the wild-type enzyme and enzymes altered in specific amino acid residues that control affinity of template binding. Future work emphasizes the role that DNA structure plays in the key polymerase function of selection of the correct nucleotide for insertion into the growing DNA strand. We are interested in the roles of individual amino acids that interact with the nascent base pair (template base and incoming nucleotide), especially arginine 72, and surrounding amino acids. More recently, we have examined the influence of alternate substrates (nucleoside triphosphate analogues) and products (pyrophosphate analogues; e.g., imidodiphosphate) on the chemical equilibrium of the nucleotidyl transferase reaction. Studies with pol beta suggest that using a pyrophosphate analogue with HIV-1 RT could overcome drug resistance exhibited by mutated form of the RT