title: Ribosomal protein L31 in Escherichia coli contributes to ribosome subunit association and translation, whereas short L31 cleaved by protease 7 reduces both activities.
abstract: Ribosomes routinely prepared from Escherichia coli strain K12 contain intact (70 amino acids) and short (62 amino acids) forms of ribosomal protein L31. By contrast, ribosomes prepared from ompT mutant cells, which lack protease 7, contain only intact L31, suggesting that L31 is cleaved by protease 7 during ribosome preparation. We compared ribosomal subunit association in wild-type and ompT-strains. In sucrose density gradient centrifugation under low Mg2+, 70S content was very high in ompT-ribosomes, but decreased in the wild-type ribosomes containing short L31. In addition, ribosomes lacking L31 failed to associate ribosomal subunits in low Mg2+. Therefore, intact L31 is required for subunit association, and the eight C-terminal amino acids contribute to the association function. In vitro translation was assayed using three different systems. Translational activities of ribosomes lacking L31 were 40% lower than those of ompT-ribosomes with one copy of intact L31, indicating that L31 is involved in translation. Moreover, in the stationary phase, L31 was necessary for 100S formation. The strain lacking L31 grew very slowly. A structural analysis predicted that the L31 protein spans the 30S and 50S subunits, consistent with the functions of L31 in 70S association, 100S formation, and translation.
authors.affiliation: Yoshida Biological Laboratory, Takehanasotoda-cho, Yamashina-ku, Kyoto, 607-8081, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Ueta
authors.affiliation: Yoshida Biological Laboratory, Takehanasotoda-cho, Yamashina-ku, Kyoto, 607-8081, Japan.|CREST, Japan Science and Technology, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Chieko
authors.identifier: http://orcid.org/0000-0003-2924-3594
authors.initials: C
authors.lastname: Wada
authors.affiliation: RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan.|Academia Sinica, Institute of Biological Chemistry, 128 Academia Road Sec. 2, Nankang, Taipei, 115, Taiwan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Bessho
authors.affiliation: CREST, Japan Science and Technology, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Maeda
authors.affiliation: Yoshida Biological Laboratory, Takehanasotoda-cho, Yamashina-ku, Kyoto, 607-8081, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Wada
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D059748:Proteolysis; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054657:Ribosome Subunits / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D012269:Ribosomal Proteins; D010447:Peptide Hydrolases