Structural insights into PPP2R5A degradation by HIV-1 Vif

Abstract

HIV-1 Vif recruits host cullin-RING-E3 ubiquitin ligase and CBFβ to degrade the cellular APOBEC3 antiviral proteins through diverse interactions. Recent evidence has shown that Vif also degrades the regulatory subunits PPP2R5(A–E) of cellular protein phosphatase 2A to induce G2/M cell cycle arrest. As PPP2R5 proteins bear no functional or structural resemblance to A3s, it is unclear how Vif can recognize different sets of proteins. Here we report the cryogenic-electron microscopy structure of PPP2R5A in complex with HIV-1 Vif–CBFβ–elongin B–elongin C at 3.58 Å resolution. The structure shows PPP2R5A binds across the Vif molecule, with biochemical and cellular studies confirming a distinct Vif–PPP2R5A interface that partially overlaps with those for A3s. Vif also blocks a canonical PPP2R5A substrate-binding site, indicating that it suppresses the phosphatase activities through both degradation-dependent and degradation-independent mechanisms. Our work identifies critical Vif motifs regulating the recognition of diverse A3 and PPP2R5A substrates, whereby disruption of these host–virus protein interactions could serve as potential targets for HIV-1 therapeutics. The authors solve a cryo-EM structure of the regulatory subunit of human protein phosphatase 2A in complex with HIV-1 Vif-containing E3 ligase, leading to improvement of our understanding of host–virus protein interactions.