title: Regulation of chaperone binding and nucleosome dynamics by key residues within the globular domain of histone H3.
abstract: BACKGROUND
  Nucleosomes have an important role in modulating access of DNA by regulatory factors. The role specific histone residues have in this process has been shown to be an important mechanism of transcription regulation. Previously, we identified eight amino acids in histones H3 and H4 that are required for nucleosome occupancy over highly transcribed regions of the genome.
  
  
  RESULTS
  We investigate the mechanism through which three of these previously identified histone H3 amino acids regulate nucleosome architecture. We find that histone H3 K122, Q120, and R49 are required for Spt2, Spt6, and Spt16 occupancies at genomic locations where transcription rates are high, but not over regions of low transcription rates. Furthermore, substitution at one residue, K122, located on the dyad axis of the nucleosome, results in improper reassembly and disassembly of nucleosomes, likely accounting for the transcription rate-dependent regulation by these mutant histones.
  
  
  CONCLUSIONS
  These data show that when specific amino acids of histone proteins are substituted, Spt2, Spt6, and Spt16 occupancies are reduced and nucleosome dynamics are altered. Therefore, these data support a mechanism for histone chaperone binding where these factors interact with histone proteins to promote their activities during transcription.
authors.affiliation: Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, 364 Plantation Street, LRB 560D, Worcester, MA 01604 USA ; Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260 USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Hainer
authors.affiliation: Shady Side Academy Senior School, 423 Fox Chapel Road, Pittsburgh, PA 15238 USA ; Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260 USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Martens
keywords: Chromatin; Histone H3 K122; Histone chaperone; SRG1/SER3; Saccharomyces cerevisiae; Spt16; Spt2; Spt6; Transcription