title: Identification of a SecM segment required for export-coupled release from elongation arrest.
abstract: SecM in Escherichia coli has two functionally crucial regions. The arrest motif near the C-terminus interacts with the ribosomal exit tunnel to arrest its own translational elongation. The signal sequence at the N-terminus directs the SecM nascent polypeptide to the Sec-mediated export pathway to release the arrested state of translation. Here, we addressed the importance of the central region of SecM. Characterization of internal substitution and deletion mutants revealed that a segment from residue 100 to residue 109 is required for the export-coupled release of the SecM nascent chain from the elongation-arrested state. Thus, the central region of SecM is not just a geometric linker but it participates actively in the regulation of translation arrest.
authors: Faculty of Life Sciences and Structural Biology Research Center, Kyoto Sangyo University, Kyoto 603-8555, Japan.
authors: Kenta
authors: K
authors: Nakamori
authors: Faculty of Life Sciences and Structural Biology Research Center, Kyoto Sangyo University, Kyoto 603-8555, Japan.
authors: Shinobu
authors: S
authors: Chiba
authors: Faculty of Life Sciences and Structural Biology Research Center, Kyoto Sangyo University, Kyoto 603-8555, Japan. Electronic address: kito@cc.kyoto-su.ac.jp.
authors: Koreaki
authors: K
authors: Ito
mesh_terms: D004926:Escherichia coli / Q000166:cytology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D021381:Protein Transport; D012270:Ribosomes / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; C497347:SecM protein, E coli; D014157:Transcription Factors
keywords: Protein translocation; Ribosome stalling; SecA; SecM; Translation arrest