Replication-independent assembly of nucleosome arrays in a novel yeast chromatin reconstitution system involves antisilencing factor Asf1p and chromodomain protein Chd1p.
Chromatin assembly in a crude DEAE (CD) fraction from budding yeast is ATP dependent and generates arrays of physiologically spaced nucleosomes which significantly protect constituent DNA from restriction endonuclease digestion. The CD fractions from mutants harboring deletions of the genes encoding histone-binding factors (NAP1, ASF1, and a subunit of CAF-I) and SNF2-like DEAD/H ATPases (SNF2, ISW1, ISW2, CHD1, SWR1, YFR038w, and SPT20) were screened for activity in this replication-independent system. ASF1 deletion substantially inhibits assembly, a finding consistent with published evidence that Asf1p is a chromatin assembly factor. Surprisingly, a strong assembly defect is also associated with deletion of CHD1, suggesting that like other SNF2-related groups of nucleic acid-stimulated ATPases, the chromodomain (CHD) group may contain a member involved in chromatin reconstitution. In contrast to the effects of disrupting ASF1 and CHD1, deletion of SNF2 is associated with increased resistance of chromatin to digestion by micrococcal nuclease. We discuss the possible implications of these findings for current understanding of the diversity of mechanisms by which chromatin reconstitution and remodeling can be achieved in vivo.
Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7. karen.robinson@ualberta.ca
Karen M
KM
Robinson
Michael C
MC
Schultz
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D020868:Gene Silencing; D005800:Genes, Fungal; D018832:Molecular Chaperones; D009154:Mutation; D009687:Nuclear Proteins; D009707:Nucleosomes / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
C109731:ASF1 protein, S cerevisiae; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D009707:Nucleosomes; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000251:Adenosine Triphosphatases; C499333:SNF2 protein, S cerevisiae