Abstract
Lentiviruses can infect non-dividing cells, and various cellular transport proteins provide crucial functions for lentiviral nuclear entry and integration. We previously showed that the viral capsid (CA) protein mediated the dependency on cellular nucleoporin (NUP) 153 during HIV-1 infection, and now demonstrate a direct interaction between the CA N-terminal domain and the phenylalanine-glycine (FG)-repeat enriched NUP153 C-terminal domain (NUP153C). NUP153C fused to the effector domains of the rhesus Trim5α restriction factor (Trim-NUP153C) potently restricted HIV-1, providing an intracellular readout for the NUP153C-CA interaction during retroviral infection. Primate lentiviruses and equine infectious anemia virus (EIAV) bound NUP153C under these conditions, results that correlated with direct binding between purified proteins in vitro. These binding phenotypes moreover correlated with the requirement for endogenous NUP153 protein during virus infection. Mutagenesis experiments concordantly identified NUP153C and CA residues important for binding and lentiviral infectivity. Different FG motifs within NUP153C mediated binding to HIV-1 versus EIAV capsids. HIV-1 CA binding mapped to residues that line the common alpha helix 3/4 hydrophobic pocket that also mediates binding to the small molecule PF-3450074 (PF74) inhibitor and cleavage and polyadenylation specific factor 6 (CPSF6) protein, with Asn57 (Asp58 in EIAV) playing a particularly important role. PF74 and CPSF6 accordingly each competed with NUP153C for binding to the HIV-1 CA pocket, and significantly higher concentrations of PF74 were needed to inhibit HIV-1 infection in the face of Trim-NUP153C expression or NUP153 knockdown. Correlation between CA mutant viral cell cycle and NUP153 dependencies moreover indicates that the NUP153C-CA interaction underlies the ability of HIV-1 to infect non-dividing cells. Our results highlight similar mechanisms of binding for disparate host factors to the same region of HIV-1 CA during viral ingress. We conclude that a subset of lentiviral CA proteins directly engage FG-motifs present on NUP153 to affect viral nuclear import.
Highlights
Retroviruses integrate their reverse transcribed genomes into host cell chromosomes to provide a permanent vantage from which to amplify themselves for subsequent transmission
Numerous nuclear transport proteins are important for HIV-1 infection, suggesting the viral nucleoprotein complex enters the nucleus by passing through nuclear pore complexes
HIV-1 was previously found to utilize cellular nucleoporin (NUP) 153 protein in a manner determined by the viral capsid protein
Summary
Retroviruses integrate their reverse transcribed genomes into host cell chromosomes to provide a permanent vantage from which to amplify themselves for subsequent transmission. The c-retrovirus Moloney murine leukemia virus (MLV) is believed to await the dissolution of the nuclear envelope during mitosis, a mechanism that limits infection by this virus to actively dividing target cells [1,2,3]. One-third of the NUPs harbor domains rich in phenylalanine-glycine (FG) motifs, commonly observed as FxF, FxFG, or GLFG patterns [8] These FG-rich domains line the central channel of the NPC, as well as the cytoplasmic and nuclear openings [9], and dictate the selective passage of macromolecules through the pore; small molecules are able to passively diffuse, while molecules greater than ,9 nm in diameter need to be ferried by specialized carrier proteins capable of interacting with the FG-based permeability barrier [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
