Passage of the HIV capsid cracks the nuclear pore

Abstract

Upon infection, human immunodeficiency virus type 1 (HIV-1) releases its cone-shaped capsid into the cytoplasm of infected T cells and macrophages. The capsid enters the nuclear pore complex (NPC), driven by interactions with numerous phenylalanine-glycine (FG)-repeat nucleoporins (FG-Nups). Whether NPCs structurally adapt to capsid passage and whether capsids are modified during passage remains unknown, however. Here, we combined super-resolution and correlative microscopy with cryoelectron tomography and molecular simulations to study the nuclear entry of HIV-1 capsids in primary human macrophages. Our data indicate that cytosolically bound cyclophilin A is stripped off capsids entering the NPC, and the capsid hexagonal lattice remains largely intact inside and beyond the central channel. Strikingly, the NPC scaffold rings frequently crack during capsid passage, consistent with computer simulations indicating the need for NPC widening. The unique cone shape of the HIV-1 capsid facilitates its entry into NPCs and helps to crack their rings.

Keywords: CLEM; HIV; HIV capsid; HIV nuclear entry; MD simulation; NPC; STED; cryo-ET; in situ cryo-ET; nuclear pore complex; subtomogram averaging.