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

Life science alliance 2022 Oct

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HIV-1 Rev mediates the nuclear export of intron-containing viral RNA transcripts and is essential for viral replication. Rev is imported into the nucleus by the host protein importin β (Impβ), but how Rev associates with Impβ is poorly understood. Here, we report biochemical, mutational, and biophysical studies of the Impβ/Rev complex. We show that Impβ binds two Rev monomers through independent binding sites, in contrast to the 1:1 binding stoichiometry observed for most Impβ cargos. Peptide scanning data and charge-reversal mutations identify the N-terminal tip of Rev helix α2 within Rev's arginine-rich motif (ARM) as a primary Impβ-binding epitope. Cross-linking mass spectrometry and compensatory mutagenesis data combined with molecular docking simulations suggest a structural model in which one Rev monomer binds to the C-terminal half of Impβ with Rev helix α2 roughly parallel to the HEAT-repeat superhelical axis, whereas the other monomer binds to the N-terminal half. These findings shed light on the molecular basis of Rev recognition by Impβ and highlight an atypical binding behavior that distinguishes Rev from canonical cellular Impβ cargos. © 2022 Spittler et al.

Citation

Didier Spittler, Rose-Laure Indorato, Elisabetta Boeri Erba, Elise Delaforge, Luca Signor, Simon J Harris, Isabel Garcia-Saez, Andrés Palencia, Frank Gabel, Martin Blackledge, Marjolaine Noirclerc-Savoye, Carlo Petosa. Binding stoichiometry and structural model of the HIV-1 Rev/importin β complex. Life science alliance. 2022 Oct;5(10)