Inverse regulatory coordination of motility and curli-mediated adhesion in Escherichia coli
Abstract
During the transition from post-exponential to stationary phase, Escherichia coli changes from the motile-planktonic to the adhesive-sedentary “lifestyle.” We demonstrate this transition to be controlled by mutual inhibition of the FlhDC/motility and σS/adhesion control cascades at two distinct hierarchical levels. At the top level, motility gene expression and the general stress response are inversely coordinated by σ70/σFliA/σS competition for core RNA polymerase and the FlhDC-controlled FliZ protein acting as a σS inhibitor. At a lower level, the signaling molecule bis-(3′–5′)-cyclic-diguanosine monophosphate (c-di-GMP) reduces flagellar activity and stimulates transcription of csgD, which encodes an essential activator of adhesive curli fimbriae expression. This c-di-GMP is antagonistically controlled by σS-regulated GGDEF proteins (mainly YegE) and YhjH, an EAL protein and c-di-GMP phosphodiesterase under FlhDC/FliA control. The switch from motility-based foraging to the general stress response and curli expression requires σS-modulated down-regulation of expression of the flagellar regulatory cascade as well as proteolysis of the flagellar master regulator FlhDC. Control of YhjH by FlhDC and of YegE by σS produces a fine-tuned checkpoint system that “unlocks” curli expression only after down-regulation of flagellar gene expression. In summary, these data reveal the logic and sequence of molecular events underlying the motile-to-adhesive “lifestyle” switch in E. coli.
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Footnotes
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↵1 Corresponding author.
↵1 E-MAIL Rhenggea{at}zedat.fu-berlin.de; FAX 49-30-838-53118.
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Supplemental material is available at http://www.genesdev.org.
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Article is online at http://www.genesdev.org/cgi/doi/10.1101/gad.475808.
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- Received February 15, 2008.
- Accepted July 1, 2008.
- Copyright © 2008, Cold Spring Harbor Laboratory Press