Structure of HIV-1 reverse transcriptase/DNA complex at 7 A resolution showing active site locations

Area of Science:

• Biochemistry
• Structural Biology
• Virology

Background:

• Human Immunodeficiency Virus (HIV) causes Acquired Immunodeficiency Syndrome (AIDS), a major global health concern.
• Current HIV treatments targeting reverse transcriptase (RT) face challenges due to rapid development of drug-resistant strains.
• Understanding HIV-1 RT structure is crucial for designing more effective antiviral therapies.

Purpose of the Study:

• To elucidate the three-dimensional structure of the HIV-1 reverse transcriptase (RT) enzyme.
• To visualize the binding interactions of RT with DNA and a neutralizing antibody.
• To identify potential sites for improved inhibitor development against HIV-1.

Main Methods:

• X-ray crystallography was used to determine the structure of a ternary complex of HIV-1 RT, a monoclonal antibody Fab fragment, and duplex DNA at 7 Å resolution.
• Difference Fourier methods were employed to localize a mercurated UTP derivative, identifying the polymerase nucleoside triphosphate binding site.
• Comparative structural analysis was performed on the RT/Fab complex with and without DNA to observe conformational changes.

Main Results:

• The double-stranded DNA was observed to bind within a groove on the surface of the HIV-1 RT enzyme.
• The structure revealed the positioning of the DNA relative to the enzyme's RNase H and polymerase domains.
• Conformational changes in the enzyme were detected upon DNA binding, particularly around the template-primer groove.

Conclusions:

• The determined structure provides a detailed molecular basis for understanding HIV-1 RT function and drug interactions.
• Identifying the nucleoside triphosphate binding site offers a target for novel drug design.
• These findings are critical for developing next-generation inhibitors to combat drug-resistant HIV strains and improve AIDS treatment.