Binding stoichiometry and structural model of the HIV-1 Rev/importin β complex

Area of Science:

• Molecular Biology
• Virology
• Structural Biology

Background:

• HIV-1 Rev protein is essential for viral replication by mediating nuclear export of viral RNA.
• Nuclear import of Rev is facilitated by importin β (Impβ), but the precise binding mechanism remains unclear.

Purpose of the Study:

• To elucidate the molecular mechanism of the interaction between HIV-1 Rev and importin β (Impβ).
• To characterize the binding stoichiometry and identify key binding epitopes.

Main Methods:

• Biochemical assays
• Mutational analysis
• Biophysical studies
• Cross-linking mass spectrometry
• Molecular docking simulations

Main Results:

• Importin β binds two Rev monomers, deviating from the typical 1:1 stoichiometry.
• The N-terminal tip of Rev helix α2 within the arginine-rich motif (ARM) is identified as a primary Impβ-binding epitope.
• A structural model suggests distinct binding sites on Impβ for each Rev monomer.

Conclusions:

• The study reveals an atypical binding mode of HIV-1 Rev to Impβ, involving two Rev monomers.
• This unique interaction is critical for Rev's function in nuclear export and viral replication.
• Findings provide insights into the structural basis of Impβ-cargo recognition.