title: Heterochromatin controls γH2A localization in Neurospora crassa.
abstract: In response to genotoxic stress, ATR and ATM kinases phosphorylate H2A in fungi and H2AX in animals on a C-terminal serine. The resulting modified histone, called γH2A, recruits chromatin-binding proteins that stabilize stalled replication forks or promote DNA double-strand-break repair. To identify genomic loci that might be prone to replication fork stalling or DNA breakage in Neurospora crassa, we performed chromatin immunoprecipitation (ChIP) of γH2A followed by next-generation sequencing (ChIP-seq). γH2A-containing nucleosomes are enriched in Neurospora heterochromatin domains. These domains are comprised of A·T-rich repetitive DNA sequences associated with histone H3 methylated at lysine-9 (H3K9me), the H3K9me-binding protein heterochromatin protein 1 (HP1), and DNA cytosine methylation. H3K9 methylation, catalyzed by DIM-5, is required for normal γH2A localization. In contrast, γH2A is not required for H3K9 methylation or DNA methylation. Normal γH2A localization also depends on HP1 and a histone deacetylase, HDA-1, but is independent of the DNA methyltransferase DIM-2. γH2A is globally induced in dim-5 mutants under normal growth conditions, suggesting that the DNA damage response is activated in these mutants in the absence of exogenous DNA damage. Together, these data suggest that heterochromatin formation is essential for normal DNA replication or repair.
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia, USA.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Sasaki
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia, USA.
authors.forename: Kelsey L
authors.initials: KL
authors.lastname: Lynch
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia, USA.
authors.forename: Caitlin V
authors.initials: CV
authors.lastname: Mueller
authors.affiliation: Department of Biochemistry and Biophysics, Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Friedman
authors.affiliation: Department of Biochemistry and Biophysics, Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Freitag
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia, USA zlewis@uga.edu.
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Lewis
mesh_terms: D015825:Chromosomes, Fungal / Q000502:physiology*; D004271:DNA, Fungal / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D006570:Heterochromatin / Q000502:physiology*; D006657:Histones / Q000378:metabolism*; D008745:Methylation; D009492:Neurospora crassa / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D006570:Heterochromatin; D006657:Histones