title: A role for TFIIIC transcription factor complex in genome organization.
abstract: Eukaryotic genome complexity necessitates boundary and insulator elements to partition genomic content into distinct domains. We show that inverted repeat (IR) boundary elements flanking the fission yeast mating-type heterochromatin domain contain B-box sequences, which prevent heterochromatin from spreading into neighboring euchromatic regions by recruiting transcription factor TFIIIC complex without RNA polymerase III (Pol III). Genome-wide analysis reveals TFIIIC with Pol III at all tRNA genes, many of which cluster at pericentromeric heterochromatin domain boundaries. However, a single tRNA(phe) gene with modest TFIIIC enrichment is insufficient to serve as boundary and requires RNAi-associated element to restrain heterochromatin spreading. Remarkably, we found TFIIIC localization without Pol III at many sites located between divergent promoters. These sites appear to act as chromosome-organizing clamps by tethering distant loci to the nuclear periphery, at which TFIIIC is concentrated into several distinct bodies. Our analyses uncover a general genome organization mechanism involving conserved TFIIIC complex.
authors.affiliation: Laboratory of Molecular Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Noma
authors.forename: Hugh P
authors.initials: HP
authors.lastname: Cam
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Maraia
authors.forename: Shiv I S
authors.initials: SI
authors.lastname: Grewal
mesh_terms: D002875:Chromosomes / Q000235:genetics; D004258:DNA Polymerase III / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D016681:Genome, Fungal / Q000235:genetics*; D006570:Heterochromatin / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D034622:RNA Interference / Q000502:physiology; D012343:RNA, Transfer / Q000235:genetics; D050436:Regulatory Elements, Transcriptional / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D019474:Transcription Factors, TFIII / Q000235:genetics*; D000098832:Transcription Factor TFIIIC
chemical_list: D006570:Heterochromatin; D019474:Transcription Factors, TFIII; D000098832:Transcription Factor TFIIIC; D012343:RNA, Transfer; D004258:DNA Polymerase III