title: Activities of Escherichia coli ribosomes in IF3 and RMF change to prepare 100S ribosome formation on entering the stationary growth phase.
abstract: The canonical ribosome cycle in bacteria consists of initiation, elongation, termination, and recycling stages. After the recycling stage, initiation factor 3 (IF3) stabilizes ribosomal dissociation by binding to 30S subunits for the next round of translation. On the other hand, during the stationary growth phase, it has been elucidated that Escherichia coli ribosomes are dimerized (100S ribosome formation) by binding ribosome modulation factor (RMF) and hibernation promoting factor (HPF), leading to a hibernation stage. This indicates that 100S ribosomes are formed after these factors are scrambled for ribosomes concomitantly with transition from the log phase to the stationary phase. In this study, to elucidate the ribosomal events before 100S ribosome formation, the relationships between protein factors (RMF and HPF) involved in 100S ribosome formation and IF3 involved in initiation complex formation were examined. As a result of in vitro assays, it was found that ribosomal dissociation activity by IF3 fell, and that ribosomal dimerization activity by RMF and HPF was elevated more when using stationary-phase ribosomes than when using log-phase ribosomes. This suggests that ribosomes change into forms which are hard to bind with IF3 and easy to form 100S ribosomes by RMF and HPF concomitantly with transition from the log phase to the stationary phase.
authors.affiliation: Department of Physics, Osaka Medical College, Takatsuki, Japan. yhide@art.osaka-med.ac.jp
authors.forename: Hideji
authors.initials: H
authors.lastname: Yoshida
authors.forename: Masami
authors.initials: M
authors.lastname: Ueta
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Maki
authors.forename: Akiko
authors.initials: A
authors.lastname: Sakai
authors.forename: Akira
authors.initials: A
authors.lastname: Wada
mesh_terms: D049109:Cell Proliferation; D004926:Escherichia coli / Q000254:growth & development* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism / Q000502:physiology*; D011073:Polyamines / Q000494:pharmacology; D039665:Prokaryotic Initiation Factor-3 / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D055550:Protein Stability / Q000187:drug effects; D012269:Ribosomal Proteins / Q000378:metabolism / Q000502:physiology*; D012270:Ribosomes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; C422854:HPF protein, E coli; D011073:Polyamines; D039665:Prokaryotic Initiation Factor-3; D012269:Ribosomal Proteins; C063545:ribosome modulation factor, E coli