title: RNase E maintenance of proper FtsZ/FtsA ratio required for nonfilamentous growth of Escherichia coli cells but not for colony-forming ability.
abstract: Inactivation or deletion of the RNase E-encoding rne gene of Escherichia coli results in the growth of bacterial cells as filamentous chains in liquid culture (K. Goldblum and D. Apirion, J. Bacteriol. 146:128-132, 1981) and the loss of colony-forming ability (CFA) on solid media. RNase E dysfunction is also associated with abnormal processing of ftsQAZ transcripts (K. Cam, G. Rome, H. M. Krisch, and J.-P. Bouché, Nucleic Acids Res. 24:3065-3070, 1996), which encode proteins having a central role in septum formation during cell division. We show here that RNase E regulates the relative abundances of FtsZ and FtsA proteins and that RNase E depletion results in decreased FtsZ, increased FtsA, and consequently an altered FtsZ/FtsA ratio. However, while restoration of the level of FtsZ to normal in rne null mutant bacteria reverses the filamentation phenotype, it does not restore CFA. Conversely, overexpression of a related RNase, RNase G, in rne-deleted bacteria restores CFA, as previously reported, without affecting FtsZ abundance. Our results demonstrate that RNase E activity is required to maintain a proper cellular ratio of the FtsZ and FtsA proteins in E. coli but that FtsZ deficiency does not account for the nonviability of cells lacking RNase E.
authors.affiliation: Stanford University School of Medicine, Department of Genetics, 300 Pasteur Drive, Stanford, CA 94305-5120, USA.
authors.forename: Masaru
authors.initials: M
authors.lastname: Tamura
authors.forename: Kangseok
authors.initials: K
authors.lastname: Lee
authors.forename: Christine A
authors.initials: CA
authors.lastname: Miller
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Moore
authors.forename: Yukio
authors.initials: Y
authors.lastname: Shirako
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Stanley N
authors.initials: SN
authors.lastname: Cohen
mesh_terms: D003470:Culture Media; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D010957:Plasmids; D015183:Restriction Mapping
chemical_list: D003470:Culture Media; D029968:Escherichia coli Proteins; C489310:FtsA protein, E coli; C076835:FtsZ84 protein, E coli; D004722:Endoribonucleases; C022537:ribonuclease E