title: Molecular Basis of Transcription-Coupled Pre-mRNA Capping.
abstract: Capping is the first step in pre-mRNA processing, and the resulting 5'-RNA cap is required for mRNA splicing, export, translation, and stability. Capping is functionally coupled to transcription by RNA polymerase (Pol) II, but the coupling mechanism remains unclear. We show that efficient binding of the capping enzyme (CE) to transcribing, phosphorylated yeast Pol II (Pol IIp) requires nascent RNA with an unprocessed 5'-triphosphate end. The transcribing Pol IIp-CE complex catalyzes the first two steps of capping, and its analysis by mass spectrometry, cryo-electron microscopy, and protein crosslinking revealed the molecular basis for transcription-coupled pre-mRNA capping. CE docks to the Pol II wall and spans the end of the RNA exit tunnel to position the CE active sites for sequential binding of the exiting RNA 5' end. Thus, the RNA 5' end triggers its own capping when it emerges from Pol II, to ensure seamless RNA protection from 5'-exonucleases during early transcription.
authors.affiliation: Gene Center Munich and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany.
authors.forename: Fuensanta W
authors.initials: FW
authors.lastname: Martinez-Rucobo
authors.affiliation: Gene Center Munich and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany; Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Kohler
authors.affiliation: Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University Padualaan 8, 3584 CH Utrecht, the Netherlands.
authors.forename: Michiel
authors.initials: M
authors.lastname: van de Waterbeemd
authors.affiliation: Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University Padualaan 8, 3584 CH Utrecht, the Netherlands.
authors.forename: Albert J R
authors.initials: AJ
authors.lastname: Heck
authors.affiliation: Gene Center Munich and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hemann
authors.affiliation: Gene Center Munich and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Herzog
authors.affiliation: Max-Planck-Institute for Biophysical Chemistry, Three-dimensional Electron Cryo-Microscopy, Am Fassberg 11, 37077 Göttingen, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Stark
authors.affiliation: Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany. Electronic address: patrick.cramer@mpibpc.mpg.de.
authors.forename: Patrick
authors.initials: P
authors.lastname: Cramer
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000737:chemistry / Q000378:metabolism; D020285:Cryoelectron Microscopy; D013058:Mass Spectrometry; D008957:Models, Genetic; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D009690:Nucleic Acid Conformation; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D012315:RNA Caps; D012319:RNA Polymerase II / Q000737:chemistry / Q000378:metabolism; D012322:RNA Precursors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012326:RNA Splicing; D012331:RNA, Fungal / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D014158:Transcription, Genetic; D000098556:mRNA Guanylyltransferases
chemical_list: D046912:Multiprotein Complexes; D012315:RNA Caps; D012322:RNA Precursors; D012331:RNA, Fungal; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D009713:Nucleotidyltransferases; D012319:RNA Polymerase II; D000098556:mRNA Guanylyltransferases; D017766:Acid Anhydride Hydrolases; C023090:RNA triphosphatase