title: Mutated K65R recombinant reverse transcriptase of human immunodeficiency virus type 1 shows diminished chain termination in the presence of 2',3'-dideoxycytidine 5'-triphosphate and other drugs.
abstract: A lysine-to-arginine substitution at amino acid 65 (K65R) in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is associated with resistance to 2',3'-dideoxycytidine (ddC), 2',3'-dideoxyinosine (ddI), and the (-) enantiomer of 2',3'-dideoxy-3'-thiacytidine (3TC). To further characterize the molecular basis of such resistance, we expressed the pp6/p51 heterodimer of wild-type RT, K65R mutated RT, and a doubly mutated (K65R/M184V) RT in Escherichia coli and assessed the characteristics of nucleotide incorporation and chain termination in cell-free reverse transcription reactions in the presence and absence of various nucleoside triphosphate analogs. These reactions employed a HIV RNA template (HIV-PBS) that contained the primer binding sequence (PBS) and the U5 and R regions of HIV-1 genomic RNA and an oligodeoxynucleotide (dPR) complementary to the HIV-1 PBS as primer. The K65R and K65R/M184V RTs showed significantly decreased chain-termination effects during polymerization with the 5'-triphosphates of ddC, 3TC, 2',3'-dideoxyadenosine, and AZT (3'-azido-3'-deoxythymidine) in comparison with wild-type RT. Detailed analysis with ddCTP and wild-type RT revealed that chain termination occurred at all guanines in the RNA template. However, the frequency of dideoxynucleoside triphosphate (ddNTP)-induced chain termination was decreased at certain guanines but not others in reactions catalyzed by K65R RT. Both the K65R mutant RT and wild-type RT had similar processive activity. These results indicate that decreased chain termination of K65R RT in the presence of ddNTPs is consistent with data obtained in viral replication assays.
authors.affiliation: McGill University AIDS Center, Lady Davis Institute-Jewish General Hospital, Montreal, QC, Canada.
authors.forename: Z
authors.initials: Z
authors.lastname: Gu
authors.forename: E J
authors.initials: EJ
authors.lastname: Arts
authors.forename: M A
authors.initials: MA
authors.lastname: Parniak
authors.forename: M A
authors.initials: MA
authors.lastname: Wainberg
mesh_terms: D001120:Arginine; D001483:Base Sequence; D003001:Cloning, Molecular; D003062:Codon; D017931:DNA Primers; D003845:Deoxycytosine Nucleotides / Q000494:pharmacology*; D054306:Dideoxynucleotides; D004926:Escherichia coli; D005260:Female; D015870:Gene Expression; D015750:Genes, gag; D054303:HIV Reverse Transcriptase; D015497:HIV-1 / Q000201:enzymology / Q000502:physiology; D006801:Humans; D008239:Lysine; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D012357:RNA, Transfer, Lys / Q000235:genetics; D012367:RNA, Viral / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000096:biosynthesis / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013698:Templates, Genetic; D014779:Virus Replication
chemical_list: D003062:Codon; D017931:DNA Primers; D003845:Deoxycytosine Nucleotides; D054306:Dideoxynucleotides; D046911:Macromolecular Substances; D012357:RNA, Transfer, Lys; D012367:RNA, Viral; D011994:Recombinant Proteins; C037406:2',3'-dideoxycytidine 5'-triphosphate; D001120:Arginine; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase; D008239:Lysine