The Y181C substitution in 3'-azido-3'-deoxythymidine-resistant human immunodeficiency virus, type 1, reverse transcriptase suppresses the ATP-mediated repair of the 3'-azido-3'-deoxythymidine 5'-monophosphate-terminated primer.
Resistance to zidovudine (3'-azido-3'-deoxythymidine, AZT) by the human immunodeficiency virus, type 1, requires multiple amino acid substitutions such as D67N/K70R/T215F/K219Q in the viral reverse transcriptase (RT). In this background of AZT resistance, additional "suppressive" substitutions such as Y181C restore sensitivity to AZT. In order to characterize the mechanism of this AZT resistance suppression, the Y181C substitution was introduced into both wild-type and AZT-resistant reverse transcriptase. The introduction of the Y181C substitution suppresses the increased repair (or unblocking) of the AZTMP-terminated primer provided by the AZT resistance substitutions in RT using either DNA or RNA templates, independently from the RT RNase H activity. Contrary to wild-type RT, the low level of unblocking activity is not due to inhibition by the next correct nucleotide binding to the RT/AZTMP-terminated primer complex. When Y181C is added to the AZT resistance substitutions, ATP binds with less affinity to the AZTMP-terminated primer-RT binary complex. These results provide an insight into one possible molecular mechanism of re-sensitization of AZT-resistant viruses by suppressive substitutions.
Selmi
Boulbaba
B
CNRS and Universités d'Aix-Marseille I and II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, ESIL-Case 925, 163 Avenue de Luminy, 13288 Marseille Cedex 09, France.
Deval
Jerome
J
Alvarez
Karine
K
Boretto
Joelle
J
Sarfati
Simon
S
Guerreiro
Catherine
C
Canard
Bruno
B
D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D019380:Anti-HIV Agents / Q000494:pharmacology*; D001435:Bacteriophages / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004260:DNA Repair; D054306:Dideoxynucleotides; D024882:Drug Resistance, Viral; D054303:HIV Reverse Transcriptase / Q000235:genetics*; D007700:Kinetics; D013942:Thymine Nucleotides / Q000494:pharmacology; D013997:Time Factors; D015215:Zidovudine / Q000031:analogs & derivatives* / Q000494:pharmacology*
D019380:Anti-HIV Agents; D017931:DNA Primers; D054306:Dideoxynucleotides; D013942:Thymine Nucleotides; C057287:3'-azido-3'-deoxythymidine 5'phosphate; D015215:Zidovudine; D000255:Adenosine Triphosphate; D004247:DNA; D054303:HIV Reverse Transcriptase