title: Molecular basis of Rrn3-regulated RNA polymerase I initiation and cell growth.
abstract: 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.
authors.affiliation: Gene Center, Department of Biochemistry, Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Blattner
authors.forename: Stefan
authors.initials: S
authors.lastname: Jennebach
authors.forename: Franz
authors.initials: F
authors.lastname: Herzog
authors.forename: Andreas
authors.initials: A
authors.lastname: Mayer
authors.forename: Alan C M
authors.initials: AC
authors.lastname: Cheung
authors.forename: Gregor
authors.initials: G
authors.lastname: Witte
authors.forename: Kristina
authors.initials: K
authors.lastname: Lorenzen
authors.forename: Karl-Peter
authors.initials: KP
authors.lastname: Hopfner
authors.forename: Albert J R
authors.initials: AJ
authors.lastname: Heck
authors.forename: Ruedi
authors.initials: R
authors.lastname: Aebersold
authors.forename: Patrick
authors.initials: P
authors.lastname: Cramer
mesh_terms: D000595:Amino Acid Sequence; D049109:Cell Proliferation; D004256:DNA Polymerase I / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D035463:Pol1 Transcription Initiation Complex Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D012694:Serine / Q000378:metabolism
chemical_list: D035463:Pol1 Transcription Initiation Complex Proteins; C101161:RRN3 protein, S cerevisiae; C428423:RRN3 protein, human; D029701:Saccharomyces cerevisiae Proteins; D012694:Serine; D004256:DNA Polymerase I; C083536:POL1 protein, S cerevisiae