The absence of the yeast chromatin assembly factor Asf1 increases genomic instability and sister chromatid exchange.
Histone chaperone Asf1 participates in heterochromatin silencing, DNA repair and regulation of gene expression, and promotes the assembly of DNA into chromatin in vitro. To determine the influence of Asf1 on genetic stability, we have analysed the effect of asf1Delta on homologous recombination. In accordance with a defect in nucleosome assembly, asf1Delta leads to a loss of negative supercoiling in plasmids. Importantly, asf1Delta increases spontaneous recombination between inverted DNA sequences. This increase correlates with an accumulation of double-strand breaks (DSBs) as determined by immunodetection of phosphorylated histone H2A and fluorescent detection of Rad52-YFP foci during S and G2/M phases. In addition, asf1Delta shows high levels of sister chromatid exchange (SCE) and is proficient in DSB-induced SCE as determined by physical analysis. Our results suggest that defective chromatin assembly caused by asf1Delta leads to DSBs that can be repaired by SCE, affecting genetic stability.
Prado
Félix
F
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain.
Cortés-Ledesma
Felipe
F
Aguilera
Andrés
A
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D042822:Genomic Instability; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D051721:Rad52 DNA Repair and Recombination Protein; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D012854:Sister Chromatid Exchange
C109731:ASF1 protein, S cerevisiae; D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D018832:Molecular Chaperones; D009707:Nucleosomes; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins