1QE1

CRYSTAL STRUCTURE OF 3TC-RESISTANT M184I MUTANT OF HIV-1 REVERSE TRANSCRIPTASE

Summary for 1QE1

• Entry DOI: 10.2210/pdb1qe1/pdb
• Related: 1C9R 1DLO 2HMI
• Descriptor: REVERSE TRANSCRIPTASE, SUBUNIT P66, REVERSE TRANSCRIPTASE, SUBUNIT P51 (2 entities in total)
• Functional Keywords: hiv, reverse transcriptase, 3tc, resistance, mutant, dna polymerase, transferase
• Biological source: Human immunodeficiency virus type 1 BH10; More
• Cellular location: Matrix protein p17: Virion (Potential). Capsid protein p24: Virion (Potential). Nucleocapsid protein p7: Virion (Potential). Reverse transcriptase/ribonuclease H: Virion (Potential). Integrase: Virion (Potential): P03366 P03366
• Total number of polymer chains: 2
• Total formula weight: 114149.93

Authors

Sarafianos, S.G.,Das, K.,Ding, J.,Hughes, S.H.,Arnold, E. (deposition date: 1999-07-12, release date: 1999-08-30, Last modification date: 2024-02-14)

Primary citation

Sarafianos, S.G.,Das, K.,Clark Jr., A.D.,Ding, J.,Boyer, P.L.,Hughes, S.H.,Arnold, E.
Lamivudine (3TC) resistance in HIV-1 reverse transcriptase involves steric hindrance with beta-branched amino acids.
Proc.Natl.Acad.Sci.USA, 96:10027-10033, 1999

PubMed 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.

PubMed: 10468556
DOI: 10.1073/pnas.96.18.10027

Experimental method

X-RAY DIFFRACTION (2.85 Å)