The Binding Interface between Human APOBEC3F and HIV-1 Vif Elucidated by Genetic and Computational Approaches

• HIV pathogenesis requires Vif-mediated degradation of host APOBEC3 enzymes
• Virus adaptation and MD simulation experiments reveal interacting amino acids
• These studies inform a structural model of the Vif-APOBEC3F interaction
• A wobble model is proposed to explain the evolution of pathogen-host interactions

SummaryAPOBEC3 family DNA cytosine deaminases provide overlapping defenses against pathogen infections. However, most viruses have elaborate evasion mechanisms such as the HIV-1 Vif protein, which subverts cellular CBF-β and a polyubiquitin ligase complex to neutralize these enzymes. Despite advances in APOBEC3 and Vif biology, a full understanding of this direct host-pathogen conflict has been elusive. We combine virus adaptation and computational studies to interrogate the APOBEC3F-Vif interface and build a robust structural model. A recurring compensatory amino acid substitution from adaptation experiments provided an initial docking constraint, and microsecond molecular dynamic simulations optimized interface contacts. Virus infectivity experiments validated a long-lasting electrostatic interaction between APOBEC3F E289 and HIV-1 Vif R15. Taken together with mutagenesis results, we propose a wobble model to explain how HIV-1 Vif has evolved to bind different APOBEC3 enzymes and, more generally, how pathogens may evolve to escape innate host defenses.

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