PMID: 30053425

Authors:

Morris KL, Buffalo CZ, Sturzel CM, Heusinger E, Kirchhoff F, Ren X, Hurley JH

Title:

HIV-1 Nefs Are Cargo-Sensitive AP-1 Trimerization Switches in Tetherin Downregulation.

Journal:

Cell. 2018 Jul 26;174(3):659-671.e14. doi: 10.1016/j.cell.2018.07.004.

Abstract:

The HIV accessory protein Nef counteracts immune defenses by subverting coated vesicle pathways. The 3.7 A cryo-EM structure of a closed trimer of the clathrin adaptor AP-1, the small GTPase Arf1, HIV-1 Nef, and the cytosolic tail of the restriction factor tetherin suggested a mechanism for inactivating tetherin by Golgi retention. The 4.3 A structure of a mutant Nef-induced dimer of AP-1 showed how the closed trimer is regulated by the dileucine loop of Nef. HDX-MS and mutational analysis were used to show how cargo dynamics leads to alternative Arf1 trimerization, directing Nef targets to be either retained at the trans-Golgi or sorted to lysosomes. Phosphorylation of the NL4-3 M-Nef was shown to regulate AP-1 trimerization, explaining how O-Nefs lacking this phosphosite counteract tetherin but most M-Nefs do not. These observations show how the higher-order organization of a vesicular coat can be allosterically modulated to direct cargoes to distinct fates.