Nup153 Unlocks the Nuclear Pore Complex for HIV-1 Nuclear Import in Non-Dividing Cells

HIV-1 displays the unique ability to infect non-dividing cells. The capsid of HIV-1 is the viral determinant for viral nuclear import. To understand the cellular factors involved in the ability of HIV-1 to infect non-dividing cells, we sought to find capsid mutations that allow the virus to infect dividing but not non-dividing cells. Because the interaction of capsid with Nup153 is important for nuclear import of HIV-1, we solved new structures of hexameric HIV-1 capsid in complex with a Nup153-derived peptide containing an FG-repeat, which we used to guide structure-based mutagenesis of the capsid-binding interface. HIV-1 viruses bearing mutations in these capsid residues were tested for their ability to infect dividing and non-dividing cells. Our results showed that HIV-1 bearing N57 substitutions infect dividing but not non-dividing cells. Interestingly, HIV-1 viruses bearing changes on residue N57 undergo reverse transcription but not nuclear import. Capsid containing changes on residue N57 also lost the ability to interact with Nup153 and CPSF6. Analysis of integration sites revealed that HIV-1 viruses bearing changes on residue N57 decreased integration into transcriptionally active genes, resembling the integration of HIV-1 in CPSF6 knockout cells or the integration of HIV-1-N74D viruses. The integration pattern of HIV-1 viruses bearing changes on N57 is explained by the loss of capsid interaction with CPSF6, whereas, the interaction of capsid with Nup153 is required for the ability of HIV-1 to infect non-dividing cells. Additionally, the observed viral integration profiles suggest that nuclear factors are more critical for site selection of integration when compared to the state of the cellular chromatin.