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| Article Authors: | S G Sarafianos; K Das; A D Clark Jr; J Ding; P L Boyer; S H Hughes; E Arnold |
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| Article Title: | Lamivudine (3TC) resistance in HIV-1 reverse transcriptase involves steric hindrance with beta-branched amino acids. |
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| Reference ID: | 1096 |
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| Abstract: | An important component of triple-drug anti-AIDS therapy is 2', 3'-dideoxy-3'-thiacytidine (3TC, lamivudine). Single mutations at residue 184 of the reverse transcriptase (RT) in HIV cause high-level resistance to 3TC and contribute to the failure of anti-AIDS combination therapy. We have determined crystal structures of the 3TC-resistant mutant HIV-1 RT (M184I) in both the presence and absence of a DNA/DNA template-primer. In the absence of a DNA substrate, the wild-type and mutant structures are very similar. However, comparison of crystal structures of M184I mutant and wild-type HIV-1 RT with and without DNA reveals repositioning of the template-primer in the M184I/DNA binary complex and other smaller changes in residues in the dNTP-binding site. On the basis of these structural results, we developed a model that explains the ability of the 3TC-resistant mutant M184I to incorporate dNTPs but not the nucleotide analog 3TCTP. In this model, steric hindrance is expected for NRTIs with beta- or L- ring configurations, as with the enantiomer of 3TC that is used in therapy. Steric conflict between the oxathiolane ring of 3TCTP and the side chain of beta-branched amino acids (Val, Ile, Thr) at position 184 perturbs inhibitor binding, leading to a reduction in incorporation of the analog. The model can also explain the 3TC resistance of analogous hepatitis B polymerase mutants. Repositioning of the template-primer as observed in the binary complex (M184I/DNA) may also occur in the catalytic ternary complex (M184I/DNA/3TCTP) and contribute to 3TC resistance by interfering with the formation of a catalytically competent closed complex. |
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| Affiliations: | Center for Advanced Biotechnology and Medicine (CABM) and Rutgers University Chemistry Department, 679 Hoes Lane, Piscataway, NJ 08854-5638, USA. |
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| Date: | 1999 |
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| Reference Type: | Literature |
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| PubMed ID: | 10468556 |
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| Journal: | Proc Natl Acad Sci U S A |
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| Journal Volume: | 96 |
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| Article Pages: | 10027-32 |
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| Journal ISSN: | 1091-6490 |
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| Article Chemical List: | Macromolecular Substances;RNA, Viral;Lamivudine;HIV Reverse Transcriptase |
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| Article MeSH List: | Allosteric Regulation; Amino Acid Sequence; Amino Acid Substitution; Conserved Sequence; Dimerization; Drug Resistance, Microbial; HIV Reverse Transcriptase(chemistry; genetics; metabolism); HIV-1(drug effects; enzymology; genetics); Humans; Lamivudine(chemistry; pharmacology); Macromolecular Substances; Models, Molecular; Molecular Sequence Data; Nucleic Acid Conformation; Point Mutation; Protein Conformation; RNA, Viral(chemistry; metabolism); Templates, Genetic |
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| Curation Last Updated: | 2013-05-28 20:05:35 |
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