The excision mechanism in reverse transcriptase: Pyrophosphate leaving and fingers opening are uncoupled events with the analogues AZT and d4T

• Type: Article in International Scientific Journal
• Date: 2007

Authors

Alexandra T P Carvalho (Author) Other; Pedro A Fernandes (Author) FCUP; Maria J Ramos (Author) FCUP

Journal

Title: Journal of Physical Chemistry B

Vol. 111

Pages: 12032-12039

ISSN: 1520-6106

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 6 Citations

Scopus - 5 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-004-6RQ

DOI: 10.1021/jp0746594

Abstract (EN): We conducted molecular dynamics simulations of complexes of HIV-1 reverse transcriptase (RT) with the substrate and the antiretrovirals AZT and d4T for which resistance emerges via the excision mechanism. It is currently believed that excision results from the inability of AZT to translocate to the P site because of the steric hindrances imposed by the azide group. However, such explanation is far from satisfactory as d4T does not have such steric hindrances and still suffers from excision. Such contradiction motivated us for the present study. The results point to a new explanation for excision. RT preferably excises these inhibitors over the substrate as a consequence of a different pattern of hydrogen bridges they establish with the N site after incorporation. In the complexes with normal nucleotides, the fingers residues K65 and R72 establish hydrogen bonds mainly with the leaving PPi. With the inhibitors, those same residues establish hydrogen bonds primarily with the substituted nucleotides. Consequently, pyrophosphate is eliminated before the opening of the fingers domain, which allows ATP binding, with subsequent excision and development of drug resistance.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8