A role for TFIIIC transcription factor complex in genome organization

Cell. 2006 Jun 2;125(5):859-72. doi: 10.1016/j.cell.2006.04.028.


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.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Chromosomes / genetics
  • DNA Polymerase III / genetics
  • Gene Expression Regulation, Fungal / genetics*
  • Genome, Fungal / genetics*
  • Heterochromatin / genetics*
  • Promoter Regions, Genetic / genetics
  • RNA Interference / physiology
  • RNA, Transfer / genetics
  • Regulatory Elements, Transcriptional / genetics
  • Repetitive Sequences, Nucleic Acid / genetics*
  • Schizosaccharomyces / genetics*
  • Schizosaccharomyces / metabolism
  • Transcription Factors, TFIII / genetics*


  • Heterochromatin
  • Transcription Factors, TFIII
  • transcription factor TFIIIC
  • RNA, Transfer
  • DNA Polymerase III