title: Structural basis of HIV-1 resistance to AZT by excision.
abstract: Human immunodeficiency virus (HIV-1) develops resistance to 3'-azido-2',3'-deoxythymidine (AZT, zidovudine) by acquiring mutations in reverse transcriptase that enhance the ATP-mediated excision of AZT monophosphate from the 3' end of the primer. The excision reaction occurs at the dNTP-binding site, uses ATP as a pyrophosphate donor, unblocks the primer terminus and allows reverse transcriptase to continue viral DNA synthesis. The excision product is AZT adenosine dinucleoside tetraphosphate (AZTppppA). We determined five crystal structures: wild-type reverse transcriptase-double-stranded DNA (RT-dsDNA)-AZTppppA; AZT-resistant (AZTr; M41L D67N K70R T215Y K219Q) RT-dsDNA-AZTppppA; AZTr RT-dsDNA terminated with AZT at dNTP- and primer-binding sites; and AZTr apo reverse transcriptase. The AMP part of AZTppppA bound differently to wild-type and AZTr reverse transcriptases, whereas the AZT triphosphate part bound the two enzymes similarly. Thus, the resistance mutations create a high-affinity ATP-binding site. The structure of the site provides an opportunity to design inhibitors of AZT-monophosphate excision.
authors.affiliation: Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey, USA.
authors.forename: Xiongying
authors.initials: X
authors.lastname: Tu
authors.forename: Kalyan
authors.initials: K
authors.lastname: Das
authors.forename: Qianwei
authors.initials: Q
authors.lastname: Han
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Bauman
authors.forename: Arthur D
authors.initials: AD
authors.lastname: Clark
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Hou
authors.forename: Yulia V
authors.initials: YV
authors.lastname: Frenkel
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Gaffney
authors.forename: Roger A
authors.initials: RA
authors.lastname: Jones
authors.forename: Paul L
authors.initials: PL
authors.lastname: Boyer
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Hughes
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Sarafianos
authors.forename: Eddy
authors.initials: E
authors.lastname: Arnold
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D019943:Amino Acid Substitution; D001665:Binding Sites / Q000187:drug effects; D018360:Crystallography, X-Ray; D004279:DNA, Viral / Q000096:biosynthesis; D003854:Deoxyribonucleotides / Q000378:metabolism; D054306:Dideoxynucleotides / Q000378:metabolism; D015195:Drug Design; D024882:Drug Resistance, Viral / Q000235:genetics / Q000502:physiology*; D015757:Genes, rev; D054303:HIV Reverse Transcriptase / Q000737:chemistry* / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D008958:Models, Molecular; D020125:Mutation, Missense; D017354:Point Mutation; D011487:Protein Conformation; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013942:Thymine Nucleotides / Q000378:metabolism; D015215:Zidovudine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*
chemical_list: C477810:AZTp4A; D004279:DNA, Viral; D003854:Deoxyribonucleotides; D054306:Dideoxynucleotides; D018894:Reverse Transcriptase Inhibitors; D013942:Thymine Nucleotides; D015215:Zidovudine; C052873:zidovudine triphosphate; D000255:Adenosine Triphosphate; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase