title: Interplay between trigger factor and other protein biogenesis factors on the ribosome.
abstract: Nascent proteins emerging from translating ribosomes in bacteria are screened by a number of ribosome-associated protein biogenesis factors, among them the chaperone trigger factor (TF), the signal recognition particle (SRP) that targets ribosomes synthesizing membrane proteins to the membrane and the modifying enzymes, peptide deformylase (PDF) and methionine aminopeptidase (MAP). Here, we examine the interplay between these factors both kinetically and at equilibrium. TF rapidly scans the ribosomes until it is stabilized on ribosomes presenting TF-specific nascent chains. SRP binding to those complexes is strongly impaired. Thus, TF in effect prevents SRP binding to the majority of ribosomes, except those presenting SRP-specific signal sequences, explaining how the small amount of SRP in the cell can be effective in membrane targeting. PDF and MAP do not interfere with TF or SRP binding to translating ribosomes, indicating that nascent-chain processing can take place before or in parallel with TF or SRP binding.
authors.affiliation: Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bornemann
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: Wolfgang
authors.initials: W
authors.lastname: Wintermeyer
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005453:Fluorescence; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000502:physiology*; D012269:Ribosomal Proteins / Q000378:metabolism*; D018271:Signal Recognition Particle / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; C512346:Map protein, E coli; D012269:Ribosomal Proteins; D018271:Signal Recognition Particle; D000581:Amidohydrolases; C084507:peptide deformylase; C403324:trigger factor, E coli; D019696:Peptidylprolyl Isomerase