The N-terminal extension of Escherichia coli ribosomal protein L20 is important for ribosome assembly, but dispensable for translational feedback control.
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.
Guillier
Maude
M
Institut de Biologie Physico-Chimique, UPR 9073 du CNRS, Unité de Régulation de l'Expression Génétique chez les Microorganismes, Paris, France.
Allemand
Frédéric
F
Graffe
Monique
M
Raibaud
Sophie
S
Dardel
Frédéric
F
Springer
Mathias
M
Chiaruttini
Claude
C
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
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C040045:L20 ribosomal protein, bacteria; D012338:RNA, Ribosomal, 23S; D012269:Ribosomal Proteins