Human FACT subunits coordinate to catalyze both disassembly and reassembly of nucleosomes

Micah J. McCauley, Michael Morse, Nicole Becker, Qi Hu, Maria Victoria Botuyan, Emily Navarrete, Ran Huo, Uma M. Muthurajan, Ioulia Rouzina, Karolin Luger, Georges Mer, L. James Maher, Mark C. Williams

Research output: Contribution to journalArticlepeer-review


The histone chaperone FACT (facilitates chromatin transcription) enhances transcription in eukaryotic cells, targeting DNA-protein interactions. FACT, a heterodimer in humans, comprises SPT16 and SSRP1 subunits. We measure nucleosome stability and dynamics in the presence of FACT and critical component domains. Optical tweezers quantify FACT/subdomain binding to nucleosomes, displacing the outer wrap of DNA, disrupting direct DNA-histone (core site) interactions, altering the energy landscape of unwrapping, and increasing the kinetics of DNA-histone disruption. Atomic force microscopy reveals nucleosome remodeling, while single-molecule fluorescence quantifies kinetics of histone loss for disrupted nucleosomes, a process accelerated by FACT. Furthermore, two isolated domains exhibit contradictory functions; while the SSRP1 HMGB domain displaces DNA, SPT16 MD/CTD stabilizes DNA-H2A/H2B dimer interactions. However, only intact FACT tethers disrupted DNA to the histones and supports rapid nucleosome reformation over several cycles of force disruption/release. These results demonstrate that key FACT domains combine to catalyze both nucleosome disassembly and reassembly.

Original languageEnglish (US)
Article number111858
JournalCell reports
Issue number13
StatePublished - Dec 27 2022


  • AFM
  • chaperone
  • chromatin
  • confocal fluorescence
  • CP: Molecular biology
  • DNA
  • energy landscape
  • FACT
  • histones
  • nucleosomes
  • optical tweezers

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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