Defects in ribosome function delay the initiation of chromosome replication in Escherichia coli

• Published in: Journal of basic microbiology Vol. 58; no. 12; pp. 1091 - 1099
• Main Authors: Zhang, Shujun, Wunier, Wunier, Yao, Yuan, Morigen, Morigen
• Format: Journal Article
• Language: English
• Published: Germany 01.12.2018
• Subjects: Acetyltransferases - genetics; Acetyltransferases - metabolism; Bacterial Proteins - biosynthesis; Cell Size; Chromosomes, Bacterial - metabolism; DNA Replication; DNA-Binding Proteins - biosynthesis; Escherichia coli; Escherichia coli - genetics; Escherichia coli - growth & development; Escherichia coli - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Gene Deletion; Phenotype; Protein Biosynthesis; Ribosomal Proteins - genetics; Ribosomal Proteins - metabolism; ribosome function; Ribosome Subunits, Small, Bacterial - genetics; Ribosome Subunits, Small, Bacterial - metabolism; rimJ; sra; rimJ; DNA replication; sra; ribosome function; Escherichia coli
• ISSN: 0233-111X; 1521-4028
• DOI: 10.1002/jobm.201800295

The Sra protein is a component of the 30S ribosomal subunit while RimJ is a ribosome‐associated protein that plays a role in the maturation of the 30S ribosomal subunit. Here we found that Δsra and ΔrimJ cells showed a delayed initiation of DNA replication, prolonged doubling time, decreased cell size, and decreased amounts of total protein and DnaA per cell compared with these observed for wild‐type cells. A temperature sensitivity test demonstrated that absence of the Sra or RimJ protein did not change the temperature sensitivity of the dnaA46, dnaB252, or dnaC2 mutants. Moreover, ectopic expression of Sra reversed the mutant phenotype while cells carrying the pACYC177‐rimJ plasmid did not reverse the rimJ mutant phenotype. The results indicate that deletion of sra or rimJ cause defects in ribosomal function and affect the translation process, leading to a decrease in synthesis of proteins including DnaA. Therefore, we conclude that Sra‐ and RimJ‐mediated ribosomal function is required for precise timing of initiation of chromosome replication.