biostudies-literatureIrwan IDU.S. Department of Health & Human Services | NIH | National Institute of Allergy and Infectious Diseases (NIAID)NIAID NIH HHSU.S. Department of Health & Human Services | NIH | National Institute of Allergy and Infectious DiseasesDuke | Center for AIDS Research, Duke UniversityDuke | Center for AIDS Research, Duke University (Duke University Center for AIDS Research)2101-2113https://www.ebi.ac.uk/biostudies/studies/S-EPMC9712108biostudies-literatureUnknown7(12)After viral entry and reverse transcription, HIV-1 proviruses that fail to integrate are epigenetically silenced, but the underlying mechanism has remained unclear. Using a genome-wide CRISPR/Cas9 knockout screen, we identified the host SMC5/6 complex as essential for this epigenetic silencing. We show that SMC5/6 binds to and then SUMOylates unintegrated chromatinized HIV-1 DNA. Inhibition of SUMOylation, either by point mutagenesis of the SMC5/6 component NSMCE2-a SUMO E3 ligase-or using the SUMOylation inhibitor TAK-981, prevents epigenetic silencing, enables transcription from unintegrated HIV-1 DNA and rescues the replication of integrase-deficient HIV-1. Finally, we show that blocking SMC5/6 complex expression, or inhibiting its SUMOylation activity, suppresses the establishment of lNature microbiologyEpigenetic silencing by the SMC5/6 complex mediates HIV-1 latency.PMC9712108R21-AI157616P30 AI064518P30-AI064518R21 AI157616Cullen BRIrwan IDBogerd HPfalseEpigenetic silencing by the SMC5/6 complex mediates HIV-1 latency.After viral entry and reverse transcription, HIV-1 proviruses that fail to integrate are epigenetically silenced, but the underlying mechanism has remained unclear. Using a genome-wide CRISPR/Cas9 knockout screen, we identified the host SMC5/6 complex as essential for this epigenetic silencing. We show that SMC5/6 binds to and then SUMOylates unintegrated chromatinized HIV-1 DNA. Inhibition of SUMOylation, either by point mutagenesis of the SMC5/6 component NSMCE2-a SUMO E3 ligase-or using the SUMOylation inhibitor TAK-981, prevents epigenetic silencing, enables transcription from unintegrated HIV-1 DNA and rescues the replication of integrase-deficient HIV-1. Finally, we show that blocking SMC5/6 complex expression, or inhibiting its SUMOylation activity, suppresses the establishment of l2022-01-01T00:00:00Z2022 Dec2026-05-28T21:29:09.263Z2025-04-19T22:50:15.94ZS-EPMC97121083637639410.1038/s41564-022-01264-z