title: mRNA-programmed translation pauses in the targeting of E. coli membrane proteins.
abstract: In all living organisms, ribosomes translating membrane proteins are targeted to membrane translocons early in translation, by the ubiquitous signal recognition particle (SRP) system. In eukaryotes, the SRP Alu domain arrests translation elongation of membrane proteins until targeting is complete. Curiously, however, the Alu domain is lacking in most eubacteria. In this study, by analyzing genome-wide data on translation rates, we identified a potential compensatory mechanism in E. coli that serves to slow down the translation during membrane protein targeting. The underlying mechanism is likely programmed into the coding sequence, where Shine-Dalgarno-like elements trigger elongation pauses at strategic positions during the early stages of translation. We provide experimental evidence that slow translation during targeting and improves membrane protein production fidelity, as it correlates with better folding of overexpressed membrane proteins. Thus, slow elongation is important for membrane protein targeting in E. coli, which utilizes mechanisms different from the eukaryotic one to control the translation speed.
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Fluman
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Sivan
authors.initials: S
authors.lastname: Navon
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Eitan
authors.initials: E
authors.lastname: Bibi
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Yitzhak
authors.initials: Y
authors.lastname: Pilpel
mesh_terms: D001412:Bacillus subtilis / Q000378:metabolism; D002462:Cell Membrane / Q000382:microbiology; D003062:Codon; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000737:chemistry*; D016296:Mutagenesis; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012270:Ribosomes / Q000737:chemistry; D018271:Signal Recognition Particle / Q000737:chemistry
chemical_list: D003062:Codon; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D018271:Signal Recognition Particle
keywords: B. subtilis; E. coli; cell biology; evolutionary biology; genomics; membrane proteins; quality control; translation rate