title: The GTP binding protein Obg homolog ObgE is involved in ribosome maturation.
abstract: Obg proteins belong to a subfamily of GTP binding proteins, which are highly conserved from bacteria to human. Mutations of obgE genes cause pleiotropic defects in various species but the function remained unclear. Here we examine the function of ObgE, the Obg homolog in Escherichia coli. The growth rate correlates with the amount of ObgE in cells. Co-fractionation experiments further suggest that ObgE binds to 30S and 50S ribosomal subunits, but not to 70S ribosome. Pull-down assays suggest that ObgE associates with several specific ribosomal proteins of 30S and 50S subunits, as well as RNA helicase CsdA. Purified ObgE cosediments with 16S and 23S ribosomal RNAs in vitro in the presence of GTP. Finally, mutation of ObgE affects pre-16Sr-RNA processing, ribosomal protein levels, and ribosomal protein modification, thereby significantly reducing 70S ribosome levels. This evidence implicates that ObgE functions in ribosomal biogenesis, presumably through the binding to rRNAs and/or rRNA-ribosomal protein complexes, perhaps as an rRNA/ribosomal protein folding chaperone or scaffold protein.
authors.affiliation: Laboratory of Plasma Membrane and Nuclear Signaling, Graduate School of Biostudies, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Sato
authors.forename: Gengo
authors.initials: G
authors.lastname: Kobayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hayashi
authors.forename: Hideji
authors.initials: H
authors.lastname: Yoshida
authors.forename: Akira
authors.initials: A
authors.lastname: Wada
authors.forename: Maki
authors.initials: M
authors.lastname: Maeda
authors.forename: Sota
authors.initials: S
authors.lastname: Hiraga
authors.forename: Kunio
authors.initials: K
authors.lastname: Takeyasu
authors.forename: Chieko
authors.initials: C
authors.lastname: Wada
mesh_terms: D003600:Cytosol / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D012336:RNA, Ribosomal, 16S / Q000378:metabolism; D012338:RNA, Ribosomal, 23S / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors
chemical_list: D029968:Escherichia coli Proteins; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S; C491572:ObgE protein, E coli; D020559:Monomeric GTP-Binding Proteins