title: RsfA (YbeB) proteins are conserved ribosomal silencing factors.
abstract: The YbeB (DUF143) family of uncharacterized proteins is encoded by almost all bacterial and eukaryotic genomes but not archaea. While they have been shown to be associated with ribosomes, their molecular function remains unclear. Here we show that YbeB is a ribosomal silencing factor (RsfA) in the stationary growth phase and during the transition from rich to poor media. A knock-out of the rsfA gene shows two strong phenotypes: (i) the viability of the mutant cells are sharply impaired during stationary phase (as shown by viability competition assays), and (ii) during transition from rich to poor media the mutant cells adapt slowly and show a growth block of more than 10 hours (as shown by growth competition assays). RsfA silences translation by binding to the L14 protein of the large ribosomal subunit and, as a consequence, impairs subunit joining (as shown by molecular modeling, reporter gene analysis, in vitro translation assays, and sucrose gradient analysis). This particular interaction is conserved in all species tested, including Escherichia coli, Treponema pallidum, Streptococcus pneumoniae, Synechocystis PCC 6803, as well as human mitochondria and maize chloroplasts (as demonstrated by yeast two-hybrid tests, pull-downs, and mutagenesis). RsfA is unrelated to the eukaryotic ribosomal anti-association/60S-assembly factor eIF6, which also binds to L14, and is the first such factor in bacteria and organelles. RsfA helps cells to adapt to slow-growth/stationary phase conditions by down-regulating protein synthesis, one of the most energy-consuming processes in both bacterial and eukaryotic cells.
authors: Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany.
authors: Roman
authors: R
authors: Häuser
authors: Markus
authors: M
authors: Pech
authors: Jaroslaw
authors: J
authors: Kijek
authors: Hiroshi
authors: H
authors: Yamamoto
authors: Björn
authors: B
authors: Titz
authors: Florian
authors: F
authors: Naeve
authors: Andrey
authors: A
authors: Tovchigrechko
authors: Kaori
authors: K
authors: Yamamoto
authors: Witold
authors: W
authors: Szaflarski
authors: Nono
authors: N
authors: Takeuchi
authors: Thorsten
authors: T
authors: Stellberger
authors: Markus E
authors: ME
authors: Diefenbacher
authors: Knud H
authors: KH
authors: Nierhaus
authors: Peter
authors: P
authors: Uetz
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D017124:Conserved Sequence; D056890:Eukaryota / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000235:genetics; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000378:metabolism; D054658:Ribosome Subunits, Large / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D012269:Ribosomal Proteins; D014157:Transcription Factors; C041174:ribosomal protein L14; C403329:rsfA protein, Bacillus subtilis