Genome-wide dynamics of Htz1, a histone H2A variant that poises repressed/basal promoters for activation through histone loss

Cell. 2005 Oct 21;123(2):219-31. doi: 10.1016/j.cell.2005.08.036.


Histone variants help specialize chromatin regions; however, their impact on transcriptional regulation is largely unknown. Here, we determined the genome-wide localization and dynamics of Htz1, the yeast histone H2A variant. Htz1 localizes to hundreds of repressed/basal Pol II promoters and prefers TATA-less promoters. Specific Htz1 deposition requires the SWR1 complex, which largely colocalizes with Htz1. Htz1 occupancy correlates with particular histone modifications, and Htz1 deposition is partially reliant on Gcn5 (a histone acetyltransferase) and Bdf1, an SWR1 complex member that binds acetylated histones. Changes in growth conditions cause a striking redistribution of Htz1 from activated to repressed/basal promoters. Furthermore, Htz1 promotes full gene activation but does not generally impact repression. Importantly, Htz1 releases from purified chromatin in vitro under conditions where H2A and H3 remain associated. We suggest that Htz1-bearing nucleosomes are deposited at repressed/basal promoters but facilitate activation through their susceptibility to loss, thereby helping to expose promoter DNA.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylation
  • Acetyltransferases / genetics
  • Acetyltransferases / metabolism
  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism
  • Chromatin / chemistry
  • Chromatin / isolation & purification
  • Chromatin / metabolism
  • Chromosomes, Fungal / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Fungal*
  • Genome, Fungal*
  • Histone Acetyltransferases / genetics
  • Histone Acetyltransferases / metabolism
  • Histones / genetics
  • Histones / metabolism*
  • Microarray Analysis
  • Models, Biological
  • Promoter Regions, Genetic*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription, Genetic
  • Transcriptional Activation


  • BDF1 protein, S cerevisiae
  • Chromatin
  • Fungal Proteins
  • Histones
  • Htz1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • YAF9 protein, S cerevisiae
  • Acetyltransferases
  • GCN5 protein, S cerevisiae
  • Histone Acetyltransferases
  • Adenosine Triphosphatases
  • Swr1 protein, S cerevisiae