title: The N-terminal extension of Escherichia coli ribosomal protein L20 is important for ribosome assembly, but dispensable for translational feedback control.
abstract: The Escherichia coli autoregulatory ribosomal protein L20 consists of two structurally distinct domains. The C-terminal domain is globular and sits on the surface of the large ribosomal subunit whereas the N-terminal domain has an extended shape and penetrates deep into the RNA-rich core of the subunit. Many other ribosomal proteins have analogous internal or terminal extensions. However, the biological functions of these extended domains remain obscure. Here we show that the N-terminal tail of L20 is important for ribosome assembly in vivo. Indeed, a truncated version of L20 without its N-terminal tail is unable to complement the deletion of rplT, the gene encoding L20. In addition, this L20 truncation confers a lethal-dominant phenotype, suggesting that the N-terminal domain is essential for cell growth because it could be required for ribosome assembly. Supporting this hypothesis, partial deletions of the N-terminal tail of the protein are shown to cause a slow-growth phenotype due to altered ribosome assembly in vivo as large amounts of intermediate 40S ribosomal particles accumulate. In addition to being a ribosomal protein, L20 also acts as an autogenous repressor. Using L20 truncations, we also show that the N-terminal tail of L20 is dispensable for autogenous control.
authors.affiliation: Institut de Biologie Physico-Chimique, UPR 9073 du CNRS, Unité de Régulation de l'Expression Génétique chez les Microorganismes, Paris, France.
authors.forename: Maude
authors.initials: M
authors.lastname: Guillier
authors.forename: Frédéric
authors.initials: F
authors.lastname: Allemand
authors.forename: Monique
authors.initials: M
authors.lastname: Graffe
authors.forename: Sophie
authors.initials: S
authors.lastname: Raibaud
authors.forename: Frédéric
authors.initials: F
authors.lastname: Dardel
authors.forename: Mathias
authors.initials: M
authors.lastname: Springer
authors.forename: Claude
authors.initials: C
authors.lastname: Chiaruttini
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D010641:Phenotype; D011132:Polyribosomes / Q000737:chemistry / Q000378:metabolism; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012338:RNA, Ribosomal, 23S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*; D017384:Sequence Deletion / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C040045:L20 ribosomal protein, bacteria; D012338:RNA, Ribosomal, 23S; D012269:Ribosomal Proteins