title: Repair-independent chromatin assembly onto active ribosomal genes in yeast after UV irradiation.
abstract: Chromatin rearrangements occur during repair of cyclobutane pyrimidine dimers (CPDs) by nucleotide excision repair (NER). Thereafter, the original structure must be restored to retain normal genomic functions. How NER proceeds through nonnucleosomal chromatin and how open chromatin is reestablished after repair are unknown. We analyzed NER in ribosomal genes (rDNA), which are present in multiple copies but only a fraction are actively transcribed and nonnucleosomal. We show that removal of CPDs is fast in the active rDNA and that chromatin reorganization occurs during NER. Furthermore, chromatin assembles on nonnucleosomal rDNA during the early events of NER but in the absence of DNA repair. The resumption of transcription after removal of CPDs correlates with the reappearance of nonnucleosomal chromatin. To date, only the passage of replication machinery was thought to package ribosomal genes in nucleosomes. In this report, we show that early events after formation of UV photoproducts in DNA also promote chromatin assembly.
authors.affiliation: Département de Microbiologie et d'Infectiologie, Faculté de Médecine, Poste 7446, Université de Sherbrooke, 3001 12th Ave. Nord, Sherbrooke, QC J1H 5N4, Canada. antonio.conconi@usherbrooke.ca
authors.forename: Antonio
authors.initials: A
authors.lastname: Conconi
authors.forename: Michel
authors.initials: M
authors.lastname: Paquette
authors.forename: Deirdre
authors.initials: D
authors.lastname: Fahy
authors.forename: Vyacheslav A
authors.initials: VA
authors.lastname: Bespalov
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Smerdon
mesh_terms: D002465:Cell Movement; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000737:chemistry* / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004260:DNA Repair; D004262:DNA Restriction Enzymes / Q000494:pharmacology; D004275:DNA, Ribosomal / Q000737:chemistry; D003850:Deoxyribonuclease I / Q000378:metabolism; D019281:Dimerization; D004307:Dose-Response Relationship, Radiation; D008957:Models, Genetic; D009707:Nucleosomes / Q000378:metabolism; D012318:RNA Polymerase I / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D013997:Time Factors; D014158:Transcription, Genetic; D014466:Ultraviolet Rays
chemical_list: D002843:Chromatin; D003432:Cross-Linking Reagents; D004275:DNA, Ribosomal; D009707:Nucleosomes; D004247:DNA; D012318:RNA Polymerase I; D004262:DNA Restriction Enzymes; D003850:Deoxyribonuclease I