Turlure, FannyMaertens, GoedeleRahman, ShailaCherepanov, PeterEngelman, Alan2019-10-052006Turlure, F. 2006. “A Tripartite DNA-Binding Element, Comprised of the Nuclear Localization Signal and Two AT-Hook Motifs, Mediates the Association of LEDGF/p75 with Chromatin in Vivo.” Nucleic Acids Research 34 (5): 1653–65. https://doi.org/10.1093/nar/gkl052.0305-10481362-4962http://nrs.harvard.edu/urn-3:HUL.InstRepos:41482966Lens epithelium-derived growth factor p75 (LEDGF/p75) is a DNA-binding, transcriptional co-activator that participates in HIV-1 integration site targeting. Using complementary approaches, we determined the mechanisms of LEDGF/p75 DNA-binding in vitro and chromatin-association in living cells. The binding of highly-purified, recombinant protein was assayed by surface plasmon resonance (SPR) and electrophoretic mobility gel shift. Neither assay revealed evidence for sequence-specific DNA-binding. Residues 146-197 spanning the nuclear localization signal (NLS) and two AT-hook motifs mediated non-specific DNA-binding, and DNA-binding deficient mutants retained the ability to efficiently stimulate HIV-1 integrase activity in vitro. Chromatin-association was assessed by visualizing the localization of EGFP fusion proteins in interphase and mitotic cells. Although a conserved N-terminal PWWP domain was not required for binding to condensed mitotic chromosomes, its deletion subtly affected the nucleoplasmic distribution of the protein during interphase. A dual AT-hook mutant associated normally with chromatin, yet when the mutations were combined with NLS changes or deletion of the PWWP domain, chromatin-binding function was lost. As the PWWP domain did not readily bind free DNA in vitro, our results indicate that chromatin-association is primarily affected through DNA-binding, with the PWWP domain likely contributing a protein interaction to the overall affinity of LEDGF/p75 for human chromatin.en-USJournal Article2019-10-0510.1093/nar/gkl052