title: Deletion of a conserved, central ribosomal intersubunit RNA bridge.
abstract: Elucidation of the structure of the ribosome has stimulated numerous proposals for the roles of specific rRNA elements, including the universally conserved helix 69 (H69) of 23S rRNA, which forms intersubunit bridge B2a and contacts the D stems of A- and P-site tRNAs. H69 has been proposed to be involved not only in subunit association and tRNA binding but also in initiation, translocation, translational accuracy, the peptidyl transferase reaction, and ribosome recycling. Consistent with such proposals, deletion of H69 confers a dominant lethal phenotype. Remarkably, in vitro assays show that affinity-purified Deltah69 ribosomes have normal translational accuracy, synthesize a full-length protein from a natural mRNA template, and support EF-G-dependent translocation at wild-type rates. However, Deltah69 50S subunits are unable to associate with 30S subunits in the absence of tRNA, are defective in RF1-catalyzed peptide release, and can be recycled in the absence of RRF.
authors.affiliation: Center for Molecular Biology of RNA, Department of Molecular, Cell and Developmental Biology, Sinsheimer Laboratories, University of California, Santa Cruz, Santa Cruz, California 95064, USA.
authors.forename: Iraj K
authors.initials: IK
authors.lastname: Ali
authors.forename: Laura
authors.initials: L
authors.lastname: Lancaster
authors.forename: Jason
authors.initials: J
authors.lastname: Feinberg
authors.forename: Simpson
authors.initials: S
authors.lastname: Joseph
authors.forename: Harry F
authors.initials: HF
authors.lastname: Noller
mesh_terms: D001483:Base Sequence; D017124:Conserved Sequence; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000378:metabolism; D009690:Nucleic Acid Conformation; D010454:Peptide Termination Factors / Q000378:metabolism; D014176:Protein Biosynthesis / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D012338:RNA, Ribosomal, 23S / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D012343:RNA, Transfer / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion
chemical_list: D029968:Escherichia coli Proteins; D010454:Peptide Termination Factors; D012333:RNA, Messenger; D012338:RNA, Ribosomal, 23S; D012269:Ribosomal Proteins; C489005:prfA protein, E coli; C087267:ribosome releasing factor; D012343:RNA, Transfer