title: Cotranslational protein folding on the ribosome monitored in real time.
abstract: Protein domains can fold into stable tertiary structures while they are synthesized on the ribosome. We used a high-performance, reconstituted in vitro translation system to investigate the folding of a small five-helix protein domain-the N-terminal domain of Escherichia coli N5-glutamine methyltransferase HemK-in real time. Our observations show that cotranslational folding of the protein, which folds autonomously and rapidly in solution, proceeds through a compact, non-native conformation that forms within the peptide tunnel of the ribosome. The compact state rearranges into a native-like structure immediately after the full domain sequence has emerged from the ribosome. Both folding transitions are rate-limited by translation, allowing for quasi-equilibrium sampling of the conformational space restricted by the ribosome. Cotranslational folding may be typical of small, intrinsically rapidly folding protein domains.
authors.affiliation: Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
authors.forename: Wolf
authors.initials: W
authors.lastname: Holtkamp
authors.affiliation: Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
authors.forename: Goran
authors.initials: G
authors.lastname: Kokic
authors.affiliation: Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Jäger
authors.affiliation: Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
authors.forename: Joerg
authors.initials: J
authors.lastname: Mittelstaet
authors.affiliation: Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH 44115, USA.
authors.forename: Anton A
authors.initials: AA
authors.lastname: Komar
authors.affiliation: Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany. rodnina@mpibpc.mpg.de.
authors.forename: Marina V
authors.initials: MV
authors.lastname: Rodnina
mesh_terms: D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D010455:Peptides / Q000737:chemistry; D014176:Protein Biosynthesis; D017510:Protein Folding; D011496:Protein Methyltransferases / Q000096:biosynthesis / Q000737:chemistry; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
chemical_list: D029968:Escherichia coli Proteins; D010455:Peptides; D011496:Protein Methyltransferases; C092404:prmC protein, E coli