Single-molecule FRET studies on SF2 helicases
  • Sungchul Hohng Ph.D
  • SLS Colloquia / May 17th 04:00pm / BLDG 110 ROOM N104
Abstract
Chromodomain-helicase-DNA-binding protein 1 (CHD1) remodels chromatin by translocating nucleosomes along DNA, but its mechanism remains poorly understood. We employed a single-molecule fluorescence approach to characterize nucleosome remodeling by yeast CHD1 (Chd1p). We show that Chd1p translocates nucleosomes in steps of multiple base pairs per ATP. ATP binding to Chd1p induces a transient unwrapping of the exit-side DNA, and facilitates nucleosome translocation. ATP hydrolysis induces nucleosome translocation, which is followed by the rewrapping upon the release of the hydrolyzed nucleotide. Multiple Chd1ps binding to a single nucleosome sequentially moves a histone octamer with a preference to the center of DNA fragments, suggesting a new mechanism for regularly spaced nucleosome generation by Chd1p. Our results reveal the unique mechanism by which Chd1p remodels nucleosomes. At the beginning of the talk, I will also briefly overview the research topics in my laboratory.