Control of ftsZ expression, cell division, and glutamine metabolism in Luria-Bertani medium by the alarmone ppGpp in Escherichia coli.
Inactivation of transcription factor sigma54, encoded by rpoN (glnF), restores high-temperature growth in Luria-Bertani (LB) medium to strains containing the heat-sensitive cell division mutation ftsZ84. Mutational defects in three other genes involved in general nitrogen control (glnD, glnG, and glnL) also suppress lethal filamentation. Since addition of glutamine to LB medium fully blocks suppression by each mutation, the underlying cause of suppression likely derives from a stringent response to the limitation of glutamine. This model is supported by several observations. The glnL mutation requires RelA-directed synthesis of the nutrient alarmone ppGpp to suppress filamentation. Artificially elevated levels of ppGpp suppress ftsZ84, as do RNA polymerase mutations that reproduce global effects of the ppGpp-induced state. Both the glnF null mutation and an elevated copy number of the relA gene similarly affect transcription from the upstream (pQ) promoters of the ftsQAZ operon, and both of these genetic conditions increase the steady-state level of the FtsZ84 protein. Physiological suppression of ftsZ84 by a high salt concentration was also shown to involve RelA. Additionally, we found that the growth of a glnF or glnD strain on LB medium depends on RelA or supplemental glutamine in the absence of RelA function. These data expand the roles for ppGpp in the regulation of glutamine metabolism and the expression of FtsZ during cell division.
Powell
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Molecular Control and Genetics, ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Maryland 21702, USA.
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D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D002455:Cell Division; D003470:Culture Media; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005973:Glutamine / Q000378:metabolism*; D006159:Guanosine Tetraphosphate / Q000096:biosynthesis / Q000378:metabolism*; D008025:Ligases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics; D009876:Operon; D051877:RNA Polymerase Sigma 54; D012808:Sigma Factor / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology; D013489:Suppression, Genetic; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D003470:Culture Media; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C076835:FtsZ84 protein, E coli; D012808:Sigma Factor; C497751:rpoN protein, E coli; D005973:Glutamine; D006159:Guanosine Tetraphosphate; D012965:Sodium Chloride; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54; D008025:Ligases; C028812:guanosine 3',5'-polyphosphate synthetases