The chemotaxis system, but not chemotaxis, is essential for swarming motility in Escherichia coli.
The chemotaxis system plays an essential role in swarm cell differentiation and motility. We show in this study that two (Tsr and Tar) of the four chemoreceptors in Escherichia coli can support swarming individually, but sensing their most powerful chemoattractants is not necessary. Conditions that abolish chemotaxis toward serine (presence of serine concentrations that saturate Tsr, or mutations in Tsr that destroy serine binding) have no effect on swarming. Similar results were obtained for the aspartate and maltose chemoreceptor Tar. We also show that although a mutation in the signaling domain of Tsr that inhibits CheA kinase abolishes swarming, nonchemotactic flagellar switch mutants can swarm. Our results suggest that during swarming, the chemoreceptors signal through the chemotaxis pathway and induce swarmer cell differentiation in response to signals other than their known chemoeffectors.
Burkart
M
M
Department of Microbiology and Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
Toguchi
A
A
Harshey
R M
RM
D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002628:Chemoreceptor Cells; D002633:Chemotaxis; D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins; D005407:Flagella / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011956:Receptors, Cell Surface / Q000502:physiology; D011994:Recombinant Proteins / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics / Q000502:physiology; D012694:Serine / Q000494:pharmacology; D013045:Species Specificity
D001426:Bacterial Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C057331:Tar protein, E coli; C057635:Tsr protein, Bacteria; D012694:Serine