title: Decreased requirement for 4.5S RNA in 16S and 23S rRNA mutants of Escherichia coli.
abstract: 4.5S RNA is the bacterial homolog of the mammalian signal recognition particle (SRP) RNA that targets ribosome-bound nascent peptides to the endoplasmic reticulum. To explore the interaction of bacterial SRP with the ribosome, we have isolated rRNA suppressor mutations in Escherichia coli that decrease the requirement for 4.5S RNA. Mutations at C732 in 16S rRNA and at A1668 and G1423 in 23S rRNA altered the cellular responses to decreases in both Ffh (the bacterial homolog of SRP54) and 4.5S RNA levels, while the C1066U mutation in 16S rRNA and G424A mutation in 23S rRNA affected the requirement for 4.5S RNA only. These data are consistent with a dual role for 4.5S RNA, one involving co-translational protein secretion by a 4.5S-Ffh complex, the other involving free 4.5S RNA.
authors.affiliation: J.W. Wilson Laboratory, Department of Molecular and Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA.
authors.forename: Carleen A
authors.initials: CA
authors.lastname: Brunelli
authors.forename: Michael
authors.initials: M
authors.lastname: O'Connor
authors.forename: Albert E
authors.initials: AE
authors.lastname: Dahlberg
mesh_terms: D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000378:metabolism; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D017354:Point Mutation; D012329:RNA, Bacterial; D012335:RNA, Ribosomal / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000378:metabolism*; D012338:RNA, Ribosomal, 23S / Q000737:chemistry / Q000378:metabolism*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D018271:Signal Recognition Particle / Q000378:metabolism
chemical_list: C409968:4.5S RNA; D029968:Escherichia coli Proteins; C082931:Ffh protein, E coli; D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S; D018271:Signal Recognition Particle