PMID:17873038

Citation	Gualdi, L, Tagliabue, L and Landini, P (2007) Biofilm formation-gene expression relay system in Escherichia coli: modulation of sigmaS-dependent gene expression by the CsgD regulatory protein via sigmaS protein stabilization. J. Bacteriol. 189:8034-43
Abstract	Bacteria can switch from a single-cell (planktonic) mode to a multicellular community (biofilm) mode via production of cell-cell aggregation and surface adhesion factors. In this report, we present evidence that the CsgD protein, a transcription regulator involved in biofilm formation in Escherichia coli, modulates the expression of the rpoS (sigma(S)) regulon. Protein pattern analysis of E. coli cells in stationary phase shows that CsgD affects the expression of several proteins encoded by sigma(S)-dependent genes. CsgD regulation of sigma(S)-dependent genes takes place at gene transcription level, does not bypass the need for rpoS, and is abolished in an rpoS-null mutant. Consistent with these results, we find that CsgD expression leads to an increase in sigma(S) intracellular concentration. Increase in sigma(S) cellular amount is mediated by CsgD-dependent transcription activation of iraP, encoding a factor involved in sigma(S) protein stabilization. Our results strongly suggest that the CsgD regulatory protein plays a major role as a relay between adhesion factors production and sigma(S)-dependent gene expression via sigma(S) protein stabilization. Direct coordination between biofilm formation and expression of the rpoS regulon could positively impact important biological processes, such as host colonization or response to environmental stresses.
Links	PubMed PMC2168689 Online version:10.1128/JB.00900-07
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Biofilms/growth & development; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Gene Expression Regulation, Bacterial; Sigma Factor/genetics; Sigma Factor/metabolism; Trans-Activators/genetics; Trans-Activators/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLI:CSGD		GO:0042710: biofilm formation	ECO:0000315:		P		Figure 1: curli fiber production due to increased penicillin production after plasmid with CsgD gene introduced.	complete CACAO 4043

References

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