The histone chaperone Asf1 increases the rate of histone eviction at the yeast PHO5 and PHO8 promoters.
Eukaryotic gene expression starts off from a largely obstructive chromatin substrate that has to be rendered accessible by regulated mechanisms of chromatin remodeling. The yeast PHO5 promoter is a well known example for the contribution of positioned nucleosomes to gene repression and for extensive chromatin remodeling in the course of gene induction. Recently, the mechanism of this remodeling process was shown to lead to the disassembly of promoter nucleosomes and the eviction of the constituent histones in trans. This finding called for a histone acceptor in trans and thus made histone chaperones likely to be involved in this process. In this study we have shown that the histone chaperone Asf1 increases the rate of histone eviction at the PHO5 promoter. In the absence of Asf1 histone eviction is delayed, but the final outcome of the chromatin transition is not affected. The same is true for the coregulated PHO8 promoter where induction also leads to histone eviction and where the rate of histone loss is reduced in asf1 strains as well, although less severely. Importantly, the final extent of chromatin remodeling is not affected. We have also presented evidence that Asf1 and the SWI/SNF chromatin remodeling complex work in distinct parallel but functionally overlapping pathways, i.e. they both contribute toward the same outcome without being mutually strictly dependent.
Korber
Philipp
P
Adolf-Butenandt-Institut, Universität München, Schillerstrasse 44, 80336 Münich, Germany. pkorber@lmu.de
Barbaric
Slobodan
S
Luckenbach
Tim
T
Schmid
Andrea
A
Schermer
Ulrike J
UJ
Blaschke
Dorothea
D
Hörz
Wolfram
W
D000135:Acid Phosphatase; D000251:Adenosine Triphosphatases; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D006657:Histones / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
C109731:ASF1 protein, S cerevisiae; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D006657:Histones; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000469:Alkaline Phosphatase; C510355:PHO8 protein, S cerevisiae; D000135:Acid Phosphatase; C488916:PHO5 protein, S cerevisiae; D000251:Adenosine Triphosphatases; C499333:SNF2 protein, S cerevisiae