Suppression of defective ribosome assembly in a rbfA deletion mutant by overexpression of Era, an essential GTPase in Escherichia coli

Koichi Inoue, Janivette Alsina, Jingqiu Chen, Masayori Inouye

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

Era is a small GTP-binding protein and essential for cell growth in Escherichia coli. it consists of two domains: N-terminal GTP-binding and C-terminal RNA-binding KH domains. It has been shown to bind to 16S rRNAs and 30S ribosomal subunits in vitro. Here, we report that a precursor of 16S rRNA accumulates in Era-depleted cells. The accumulation of the precursors is also seen in a cold-sensitive mutant, E200K, in which the mutation site is located in the C-terminal domain. The major precursor molecule accumulated seems to be 17S rRNA, containing extra sequences at both 5′ and 3′ ends of 16S rRNA. Moreover, the amounts of both 30S and 50S ribosomal subunits relative to the amount of 70S monosomes increase in Era-depleted and E200K mutant cells. The C-terminal KH domain has a high structural similarity to the RbfA protein, a cold shock protein that also specifically associates with 30S ribosomal subunits. RbfA is essential for cell growth at low temperature, and a precursor of 16S rRNA accumulates in an rbfA deletion strain. The 16S rRNA precursor seems to be identical in size to that accumulated in Era mutant cells. Surprisingly, the cold-sensitive cell growth of the rbfA deletion cells was partially suppressed by overproduction of the wild-type Era. The C-terminal domain alone was not able to suppress the cold-sensitive phenotype, whereas Era-dE, which has a 10-residue deletion in a putative effector region of the N-terminal domain, functioned as a more efficient suppressor than the wild-type Era. It was found that Era-dE suppressed defective 16S rRNA maturation, resuming a normal polysome profile to reduce highly accumulated free 30S and 50S subunits in the rbfA deletion cells. These results indicate that Era is involved in 16S rRNA maturation and ribosome assembly.

Original languageEnglish (US)
Pages (from-to)1005-1016
Number of pages12
JournalMolecular microbiology
Volume48
Issue number4
DOIs
StatePublished - May 1 2003

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GTP Phosphohydrolases
Ribosomes
Escherichia coli
Ribosome Subunits
RNA Precursors
Cold Shock Proteins and Peptides
Growth
Polyribosomes
Guanosine Triphosphate
GTP-Binding Proteins
Phenotype
Mutation
Temperature

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Molecular Biology

Cite this

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title = "Suppression of defective ribosome assembly in a rbfA deletion mutant by overexpression of Era, an essential GTPase in Escherichia coli",
abstract = "Era is a small GTP-binding protein and essential for cell growth in Escherichia coli. it consists of two domains: N-terminal GTP-binding and C-terminal RNA-binding KH domains. It has been shown to bind to 16S rRNAs and 30S ribosomal subunits in vitro. Here, we report that a precursor of 16S rRNA accumulates in Era-depleted cells. The accumulation of the precursors is also seen in a cold-sensitive mutant, E200K, in which the mutation site is located in the C-terminal domain. The major precursor molecule accumulated seems to be 17S rRNA, containing extra sequences at both 5′ and 3′ ends of 16S rRNA. Moreover, the amounts of both 30S and 50S ribosomal subunits relative to the amount of 70S monosomes increase in Era-depleted and E200K mutant cells. The C-terminal KH domain has a high structural similarity to the RbfA protein, a cold shock protein that also specifically associates with 30S ribosomal subunits. RbfA is essential for cell growth at low temperature, and a precursor of 16S rRNA accumulates in an rbfA deletion strain. The 16S rRNA precursor seems to be identical in size to that accumulated in Era mutant cells. Surprisingly, the cold-sensitive cell growth of the rbfA deletion cells was partially suppressed by overproduction of the wild-type Era. The C-terminal domain alone was not able to suppress the cold-sensitive phenotype, whereas Era-dE, which has a 10-residue deletion in a putative effector region of the N-terminal domain, functioned as a more efficient suppressor than the wild-type Era. It was found that Era-dE suppressed defective 16S rRNA maturation, resuming a normal polysome profile to reduce highly accumulated free 30S and 50S subunits in the rbfA deletion cells. These results indicate that Era is involved in 16S rRNA maturation and ribosome assembly.",
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Suppression of defective ribosome assembly in a rbfA deletion mutant by overexpression of Era, an essential GTPase in Escherichia coli. / Inoue, Koichi; Alsina, Janivette; Chen, Jingqiu; Inouye, Masayori.

In: Molecular microbiology, Vol. 48, No. 4, 01.05.2003, p. 1005-1016.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Suppression of defective ribosome assembly in a rbfA deletion mutant by overexpression of Era, an essential GTPase in Escherichia coli

AU - Inoue, Koichi

AU - Alsina, Janivette

AU - Chen, Jingqiu

AU - Inouye, Masayori

PY - 2003/5/1

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