title: Trans-translation ensures timely initiation of DNA replication and DnaA synthesis in Escherichia coli.
abstract: The trans-translation pathway, mediated by the transfer messenger RNA (tmRNA; encoded by the ssrA gene) and the SmpB protein (tmRNA-binding protein expressed in Salmonella enterica), which is conserved in bacteria, is required for various cellular processes. A previous study has shown that trans-translation is required to ensure timely (non-delayed) dnaA transcription and consequent initiation of DNA replication in Caulobacter crescentus. In this study, we observed that initiation of chromosome replication was delayed in Escherichia coli lacking the smpB and/or ssrA genes (DssrA, DsmpB, or DsmpBDssrA mutants). We observed that the growth rate of the mutant cells was much slower than that of its wild-type counterpart. However, the delayed initiation of replication and slower growth in the DssrA or DsmpB mutants were reversed by ectopic expression of tmRNA or SmpB. A synchronized DsmpBDssrA cell culture containing the dnaC2 mutant allele showed delayed protein (total and DnaA) accumulation per cell; DnaA accumulation was also delayed in the DsmpB. These results indicated that absence of trans-translation leads to a delay in initiation of DNA replication, synthesis of total protein (including DnaA), and a decrease in E. coli growth rate. In summary, we propose that the trans-translation pathway is required to ensure timely initiation of replication, protein synthesis, and subsequent cell cycle progression.
authors.affiliation: School of Life Sciences, Inner Mongolia University, Hohhot, China.
authors.forename: W
authors.initials: W
authors.lastname: Wurihan
authors.affiliation: School of Life Sciences, Inner Mongolia University, Hohhot, China.
authors.forename: W
authors.initials: W
authors.lastname: Wunier
authors.affiliation: School of Life Sciences, Inner Mongolia University, Hohhot, China.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.affiliation: School of Life Sciences, Inner Mongolia University, Hohhot, China.
authors.forename: L F
authors.initials: LF
authors.lastname: Fan
authors.affiliation: School of Life Sciences, Inner Mongolia University, Hohhot, China morigenm@hotmail.com.
authors.forename: M
authors.initials: M
authors.lastname: Morigen
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D016935:Caulobacter crescentus / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D011485:Protein Binding; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D019779:Salmonella enterica / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; C071702:DnaC protein, E coli; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; C430328:small protein B; C096222:tmRNA