title: An extracellular factor regulates expression of sdiA, a transcriptional activator of cell division genes in Escherichia coli.
abstract: The sdiA gene codes for a protein that regulates expression of the ftsQAZ cluster of essential cell division genes of Escherichia coli. SdiA up-regulates the ftsQ2p promoter that initiates transcription into the ftsQAZ cluster. In this paper, we report that expression of sdiA is itself regulated by a factor that is released into the growth medium by E. coli. When medium that had previously supported growth of E. coli (conditioned medium) was used to support growth of an indicator E. coli strain that contained an sdiA-lacZ transcriptional reporter, there was a 50 to 80% decrease in sdiA expression as monitored by beta-galactosidase activity. The down-regulation of PsdiA was associated with a decrease in expression of the SdiA target promoter ftsQ2p, as monitored by expression of an ftsQ2p-lacZ transcriptional fusion. An effect of conditioned medium on ftsQ2p expression was not seen when the wild-type sdiA gene was disrupted by insertional mutagenesis, indicating that the effect on ftsQ2p expression was secondary to the down-regulation of PsdiA. Conditioned medium had no effect on expression of Plac, PrpoS, or several other promoters associated with the ftsQAZ gene cluster (ftsQ1p and ftsZ1-4p). This suggests that the response is specific for PsdiA and for promoters that are regulated by the sdiA gene product and that cell-to-cell signalling may play a role in regulating expression of this group of genes.
authors.affiliation: Department of Microbiology, University of Connecticut Health Center, Farmington 06030-3205, USA.
authors.forename: J
authors.initials: J
authors.lastname: García-Lara
authors.forename: L H
authors.initials: LH
authors.lastname: Shang
authors.forename: L I
authors.initials: LI
authors.lastname: Rothfield
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis; D002450:Cell Communication; D002455:Cell Division / Q000187:drug effects; D017077:Culture Media, Conditioned; D003598:Cytoskeletal Proteins; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000254:growth & development*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial; D017930:Genes, Reporter; D006131:Growth Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D008565:Membrane Proteins / Q000096:biosynthesis; D015534:Trans-Activators / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D017077:Culture Media, Conditioned; D003598:Cytoskeletal Proteins; D029968:Escherichia coli Proteins; C065103:FtsA protein, Bacteria; C489310:FtsA protein, E coli; C068023:FtsQ protein, E coli; C071525:FtsZ protein, Bacteria; D006131:Growth Inhibitors; D008565:Membrane Proteins; C097686:SdiA protein, bacteria; D015534:Trans-Activators; C490806:sdiA protein, E coli; C088386:homoserine lactone; D015107:4-Butyrolactone