Partial depletion of histone H4 increases homologous recombination-mediated genetic instability.
DNA replication can be a source of genetic instability. Given the tight connection between DNA replication and nucleosome assembly, we analyzed the effect of a partial depletion of histone H4 on genetic instability mediated by homologous recombination. A Saccharomyces cerevisiae strain was constructed in which the expression of histone H4 was driven by the regulated tet promoter. In agreement with defective nucleosome assembly, partial depletion of histone H4 led to subtle changes in plasmid superhelical density and chromatin sensitivity to micrococcal nuclease. Under these conditions, homologous recombination between ectopic DNA sequences was increased 20-fold above the wild-type levels. This hyperrecombination was not associated with either defective repair or transcription but with an accumulation of recombinogenic DNA lesions during the S and G(2)/M phases, as determined by an increase in the proportion of budded cells containing Rad52-yellow fluorescent protein foci. Consistently, partial depletion of histone H4 caused a delay during the S and G(2)/M phases. Our results suggest that histone deposition defects lead to the formation of recombinogenic DNA structures during replication that increase genomic instability.
Prado
Félix
F
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Seville, Spain.
Aguilera
Andrés
A
D000107:Acetylation; D015825:Chromosomes, Fungal / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D008836:Micrococcal Nuclease / Q000235:genetics / Q000378:metabolism; D009707:Nucleosomes / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D051721:Rad52 DNA Repair and Recombination Protein; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D006657:Histones; D009707:Nucleosomes; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D008836:Micrococcal Nuclease