Program in Molecular Medicine
Immunology and Infectious Disease | Virology | Virus Diseases
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.
Capsid, Coumermycin-A1, HIV-1, Integration, Nucleoporins, Nucleus, Nup153, Uncoating
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DOI of Published Version
Retrovirology. 2016 Apr 23;13:28. doi: 10.1186/s12977-016-0262-0. Link to article on publisher's site
Chen N, Zhou L, Gane PJ, Opp S, Ball NJ, Nicastro G, Zufferey M, Buffone C, Luban J, Selwood D, Diaz-Griffero F, Taylor I, Fassati A. (2016). HIV-1 capsid is involved in post-nuclear entry steps. Open Access Articles. https://doi.org/10.1186/s12977-016-0262-0. Retrieved from https://escholarship.umassmed.edu/oapubs/2855
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This work is licensed under a Creative Commons Attribution 4.0 License.