Structures of HIV-1 reverse transcriptase with pre- and post-translocation AZTMP-terminated DNA.
AZT (3'-azido-3'-deoxythymidine) resistance involves the enhanced excision of AZTMP from the end of the primer strand by HIV-1 reverse transcriptase. This reaction can occur when an AZTMP-terminated primer is bound at the nucleotide-binding site (pre-translocation complex N) but not at the 'priming' site (post-translocation complex P). We determined the crystal structures of N and P complexes at 3.0 and 3.1 A resolution. These structures provide insight into the structural basis of AZTMP excision and the mechanism of translocation. Docking of a dNTP in the P complex structure suggests steric crowding in forming a stable ternary complex that should increase the relative amount of the N complex, which is the substrate for excision. Structural differences between complexes N and P suggest that the conserved YMDD loop is involved in translocation, acting as a springboard that helps to propel the primer terminus from the N to the P site after dNMP incorporation.
Sarafianos
Stefan G
SG
Center for Advanced Biotechnology and Medicine, 679 Hoes Lane, Piscataway, NJ 08854-5638, USA.
Clark
Arthur D
AD
Das
Kalyan
K
Tuske
Steve
S
Birktoft
Jens J
JJ
Ilankumaran
Palanichamy
P
Ramesha
Andagar R
AR
Sayer
Jane M
JM
Jerina
Donald M
DM
Boyer
Paul L
PL
Hughes
Stephen H
SH
Arnold
Eddy
E
D004247:DNA / Q000096:biosynthesis / Q000378:metabolism*; D054306:Dideoxynucleotides; D024882:Drug Resistance, Viral / Q000502:physiology; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*; D013942:Thymine Nucleotides / Q000378:metabolism*; D015215:Zidovudine / Q000031:analogs & derivatives* / Q000378:metabolism*
D054306:Dideoxynucleotides; D013942:Thymine Nucleotides; C057287:3'-azido-3'-deoxythymidine 5'phosphate; D015215:Zidovudine; D004247:DNA; D012194:RNA-Directed DNA Polymerase