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Molecular basis of Rrn3-regulated RNA polymerase I initiation and cell growth.

Cell growth is regulated during RNA polymerase (Pol) I transcription initiation by the conserved factor Rrn3/TIF-IA in yeast/humans. Here we provide a structure-function analysis of Rrn3 based on a combination of structural biology with in vivo and in vitro functional assays. The Rrn3 crystal structure reveals a unique HEAT repeat fold and a surface serine patch. Phosphorylation of this patch represses human Pol I transcription, and a phospho-mimetic patch mutation prevents Rrn3 binding to Pol I in vitro and reduces cell growth and Pol I gene occupancy in vivo. Cross-linking indicates that Rrn3 binds Pol I between its subcomplexes, AC40/19 and A14/43, which faces the serine patch. The corresponding region of Pol II binds the Mediator head that cooperates with transcription factor (TF) IIB. Consistent with this, the Rrn3-binding factor Rrn7 is predicted to be a TFIIB homolog. This reveals the molecular basis of Rrn3-regulated Pol I initiation and cell growth, and indicates a general architecture of eukaryotic transcription initiation complexes.

Pubmed ID: 21940764


  • Blattner C
  • Jennebach S
  • Herzog F
  • Mayer A
  • Cheung AC
  • Witte G
  • Lorenzen K
  • Hopfner KP
  • Heck AJ
  • Aebersold R
  • Cramer P


Genes & development

Publication Data

October 1, 2011

Associated Grants


Mesh Terms

  • Amino Acid Sequence
  • Cell Proliferation
  • DNA Polymerase I
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Pol1 Transcription Initiation Complex Proteins
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Multimerization
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Sequence Alignment
  • Serine