Systematic analysis of the protein interaction network for the human transcription machinery reveals the identity of the 7SK capping enzyme

  • Mol Cell. 2007 Jul 20;27(2):262-274. doi: 10.1016/j.molcel.2007.06.027.
Célia Jeronimo  1 ,  Diane Forget  1 ,  Annie Bouchard  1 ,  Qintong Li  2 ,  Gordon Chua  3 ,  Christian Poitras  1 ,  Cynthia Thérien  1 ,  Dominique Bergeron  1 ,  Sylvie Bourassa  4 ,  Jack Greenblatt  3 ,  Benoit Chabot  5 ,  Guy G Poirier  4 ,  Timothy R Hughes  3 ,  Mathieu Blanchette  6 ,  David H Price  2 ,  Benoit Coulombe  7
Affiliations
  • 1. Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada.
  • 2. Biochemistry Department, University of Iowa, Iowa City, IA 52242-1109, USA.
  • 3. Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5G 1L6, Canada.
  • 4. Centre hospitalier universitaire de Québec, Université Laval, Québec, QC G1V 4G2, Canada.
  • 5. Département de microbiologie et infectiologie, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.
  • 6. McGill Centre for Bioinformatics, McGill University, Montréal, QC H3A 2B4, Canada.
  • 7. Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada. Electronic address: [email protected].
PMID: 17643375 DOI: 10.1016/j.molcel.2007.06.027
Abstract

We have performed a survey of soluble human protein complexes containing components of the transcription and RNA processing machineries using protein affinity purification coupled to mass spectrometry. Thirty-two tagged polypeptides yielded a network of 805 high-confidence interactions. Remarkably, the network is significantly enriched in proteins that regulate the formation of protein complexes, including a number of previously uncharacterized proteins for which we have inferred functions. The RNA polymerase II (RNAP II)-associated proteins (RPAPs) are physically and functionally associated with RNAP II, forming an interface between the enzyme and chaperone/scaffolding proteins. BCDIN3 is the 7SK snRNA methylphosphate capping enzyme (MePCE) present in an snRNP complex containing both RNA processing and transcription factors, including the elongation factor P-TEFb. Our results define a high-density protein interaction network for the mammalian transcription machinery and uncover multiple regulatory factors that target the transcription machinery.