PMID:15148364

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Citation

Buskiewicz, I, Deuerling, E, Gu, SQ, Jöckel, J, Rodnina, MV, Bukau, B and Wintermeyer, W (2004) Trigger factor binds to ribosome-signal-recognition particle (SRP) complexes and is excluded by binding of the SRP receptor. Proc. Natl. Acad. Sci. U.S.A. 101:7902-6

Abstract

Trigger factor (TF) and signal recognition particle (SRP) bind to the bacterial ribosome and are both crosslinked to protein L23 at the peptide exit, where they interact with emerging nascent peptide chains. It is unclear whether TF and SRP exclude one another from their ribosomal binding site(s). Here we show that SRP and TF can bind simultaneously to ribosomes or ribosome nascent-chain complexes exposing a SRP-specific signal sequence. Based on changes of the crosslinking pattern and on results obtained by fluorescence measurements using fluorescence-labeled SRP, TF binding induces structural changes in the ribosome-SRP complex. Furthermore, we show that binding of the SRP receptor, FtsY, to ribosome-bound SRP excludes TF from the ribosome. These results suggest that TF and SRP sample nascent chains on the ribosome in a nonexclusive fashion. The decision for ribosome nascent-chain complexes exposing a signal sequence to enter SRP-dependent membrane targeting seems to be determined by the binding of SRP, which is stabilized by signal sequence recognition, and promoted by the exclusion of TF due to the binding of the SRP receptor to ribosome-bound SRP.

Links

PubMed PMC419529 Online version:10.1073/pnas.0402231101

Keywords

Bacterial Proteins/metabolism; Bacterial Proteins/ultrastructure; Binding Sites; Cross-Linking Reagents; Escherichia coli; Escherichia coli Proteins/antagonists & inhibitors; Escherichia coli Proteins/metabolism; Escherichia coli Proteins/ultrastructure; Fluorescence; Macromolecular Substances; Models, Biological; Peptidylprolyl Isomerase/antagonists & inhibitors; Peptidylprolyl Isomerase/metabolism; Peptidylprolyl Isomerase/ultrastructure; Protein Binding; Receptors, Cytoplasmic and Nuclear/metabolism; Receptors, Cytoplasmic and Nuclear/ultrastructure; Receptors, Peptide/metabolism; Ribosomes/chemistry; Ribosomes/metabolism; Signal Recognition Particle/chemistry; Signal Recognition Particle/metabolism; Signal Recognition Particle/ultrastructure

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