PMID:15743952

Citation	Jubelin, G, Vianney, A, Beloin, C, Ghigo, JM, Lazzaroni, JC, Lejeune, P and Dorel, C (2005) CpxR/OmpR interplay regulates curli gene expression in response to osmolarity in Escherichia coli. J. Bacteriol. 187:2038-49
Abstract	Curli fibers could be described as a virulence factor able to confer adherence properties to both abiotic and eukaryotic surfaces. The ability to adapt rapidly to changing environmental conditions through signal transduction pathways is crucial for the growth and pathogenicity of bacteria. OmpR was shown to activate csgD expression, resulting in curli production. The CpxR regulator was shown to negatively affect curli gene expression when binding to its recognition site that overlaps the csgD OmpR-binding site. This study was undertaken to clarify how the interplay between the two regulatory proteins, OmpR and CpxR, can affect the transcription of the curli gene in response to variation of the medium osmolarity. Band-shift assays with purified CpxR proteins indicate that CpxR binds to the csgD promoter region at multiple sites that are ideally positioned to explain the csg repression activity of CpxR. To understand the physiological meaning of this in vitro molecular phenomenon, we analyzed the effects of an osmolarity shift on the two-component pathway CpxA/CpxR. We establish here that the Cpx pathway is activated at both transcriptional and posttranscriptional levels in response to a high osmolarity medium and that CpxR represses csgD expression in high-salt-content medium, resulting in low curli production. However, csgD repression in response to high sucrose content is not mediated by CpxR but by the global regulatory protein H-NS. Therefore, multiple systems (EnvZ/OmpR, Cpx, Rcs, and H-NS) appear to be involved in sensing environmental osmolarity, leading to sophisticated regulation of the curli genes.
Links	PubMed PMC1064031 Online version:10.1128/JB.187.6.2038-2049.2005
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Base Sequence; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Molecular Sequence Data; Promoter Regions, Genetic/physiology; Repressor Proteins/metabolism; Saline Solution, Hypertonic; Trans-Activators/genetics; Trans-Activators/metabolism; Water-Electrolyte Balance/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLI:CPXR	involved_in	GO:0045893: positive regulation of transcription, DNA-templated	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
ECOLI:CPXR		GO:0045893: positive regulation of transcription, DNA-dependent	ECO:0000314:		P		Fig 5.	complete CACAO 7514

References

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