HIV-1 capsid is involved in post-nuclear entry steps. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Chen, Nan-Yu; Zhou, Lihong; Gane, Paul; Opp, Silvana; Ball, Neil; Nicastro, Giuseppe; Zufferey, Madeleine; Buffone, Cindy; Luban, Jeremy; Selwood, David; Diaz-Griffero, Felipe; Taylor, Ian; Fassati, Ariberto
• Is Part Of: Retrovirology. Volume 13:Issue 1(2016)
• Page Start: 1
• Page End: 16
• Publication Date: 2016-12
• Subjects: HIV-1 -- Capsid -- Nucleus -- Integration -- Coumermycin-A1 -- Nup153 -- Nucleoporins -- Uncoating; Retroviruses -- Periodicals; 579.2569
• DOI: 10.1186/s12977-016-0262-0
• Languages: English
• ISSNs: 1742-4690

Abstract

Abstract Background HIV-1 capsid influences viral uncoating and nuclear import. Some capsid is detected in the nucleus but it is unclear if it has any function. We reported that the antibiotic Coumermycin-A1 (C-A1) inhibits HIV-1 integration and that a capsid mutation confers resistance to C-A1, suggesting that capsid might affect post-nuclear entry steps. Results Here we report that C-A1 inhibits HIV-1 integration in a capsid-dependent way. Using molecular docking, we identify an extended binding pocket delimited by two adjacent capsid monomers where C-A1 is predicted to bind. Isothermal titration calorimetry confirmed that C-A1 binds to hexameric capsid. Cyclosporine washout assays in Jurkat CD4+ T cells expressing engineered human TRIMCyp showed that C-A1 causes faster and greater escape from TRIMCyp restriction. Sub-cellular fractionation showed that small amounts of capsid accumulated in the nuclei of infected cells and C-A1 reduced the nuclear capsid. A105S and N74D capsid mutant viruses did not accumulate capsid in the nucleus, irrespective of C-A1 treatment. Depletion of Nup153, a nucleoporin located at the nuclear side of the nuclear pore that binds to HIV-1 capsid, made the virus less susceptible to TRIMCyp restriction, suggesting that Nup153 may help maintain some integrity of the viral core in the nucleus. Furthermore C-A1 increased binding of CPSF6, a nuclear protein, to capsid. Conclusions Our results indicate that capsid is involved in post-nuclear entry steps preceding integration.