title: An RNA polymerase III-dependent heterochromatin barrier at fission yeast centromere 1.
abstract: Heterochromatin formation involves the nucleation and spreading of structural and epigenetic features along the chromatin fiber. Chromatin barriers and associated proteins counteract the spreading of heterochromatin, thereby restricting it to specific regions of the genome. We have performed gene expression studies and chromatin immunoprecipitation on strains in which native centromere sequences have been mutated to study the mechanism by which a tRNA(Alanine) gene barrier (cen1 tDNA(Ala)) blocks the spread of pericentromeric heterochromatin at the centromere of chromosome 1 (cen1) in the fission yeast, Schizosaccharomyces pombe. Within the centromere, barrier activity is a general property of tDNAs and, unlike previously characterized barriers, requires the association of both transcription factor IIIC and RNA Polymerase III. Although the cen1 tDNA(Ala) gene is actively transcribed, barrier activity is independent of transcriptional orientation. These findings provide experimental evidence for the involvement of a fully assembled RNA polymerase III transcription complex in defining independent structural and functional domains at a eukaryotic centromere.
authors.affiliation: Institute for Genome Sciences and Policy, Duke University, Durham, North Carolina, United States of America. kristin.scott@duke.edu
authors.forename: Kristin C
authors.initials: KC
authors.lastname: Scott
authors.forename: Caroline V
authors.initials: CV
authors.lastname: White
authors.forename: Huntington F
authors.initials: HF
authors.lastname: Willard
mesh_terms: D000409:Alanine / Q000737:chemistry; D002453:Cell Cycle; D002503:Centromere / Q000648:ultrastructure; D002843:Chromatin; D005656:Fungal Proteins; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D006570:Heterochromatin / Q000737:chemistry*; D008954:Models, Biological; D010957:Plasmids / Q000378:metabolism; D012320:RNA Polymerase III / Q000737:chemistry*; D012343:RNA, Transfer / Q000737:chemistry; D012568:Schizosaccharomyces / Q000378:metabolism / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry
chemical_list: D002843:Chromatin; D005656:Fungal Proteins; D006570:Heterochromatin; D029702:Schizosaccharomyces pombe Proteins; D012343:RNA, Transfer; D012320:RNA Polymerase III; D000409:Alanine