Cpx signaling pathway monitors biogenesis and affects assembly and expression of P pili

Hung, Danielle L.; Raivio, Tracy; Jones, C. Hal; Silhavy, Thomas J.; Hultgren, Scott J.

doi:10.1093/emboj/20.7.1508

Cited by 168 publications

(180 citation statements)

References 79 publications

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“…Such differential actions are also observed for NanR and NagC. CpxR and OmpR control the formation of adhesion structures such as curli and Pap pili (9,17,21). It would not be surprising if, like NanR, NagC, and OmpR, CpxR plays a role in the control of type 1 fimbriation.…”

Section: Discussionmentioning

confidence: 85%

Function and Expression of an N -Acetylneuraminic Acid-Inducible Outer Membrane Channel in Escherichia coli

et al. 2005

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The Escherichia coli yjhA (renamed nanC) gene encodes a protein of the KdgM family of outer membranespecific channels. It is transcribed divergently from fimB, a gene involved in the site-specific inversion of the region controlling transcription of the fimbrial structural genes but is separated from it by one of the largest intergenic regions in E. coli. We show that nanC expression is induced by N-acetylneuraminic acid and modulated by N-acetylglucosamine. This regulation occurs via the NanR and NagC regulators, which also control fimB expression. nanC expression is also activated by the regulators cyclic AMP-catabolite activator protein, OmpR, and CpxR. When the NanC protein was reconstituted into liposomes, it formed channels with a conductance of 450 pS at positive potential and 300 to 400 pS at negative potential in 800 mM KCl. The channels had a weak anionic selectivity. In an ompR background, where the general porins OmpF and OmpC are absent, NanC is required for growth of E. coli on N-acetylneuraminic acid as the sole carbon source. All these results suggest that NanC is an N-acetylneuraminic acid outer membrane channel protein.Porins are proteins that form water-filled channels across the outer membrane of gram-negative bacteria. These channels allow the diffusion of hydrophilic molecules (Ͻ600 Da for the general porins OmpF and OmpC) into the periplasm with no particular substrate specificity. In Escherichia coli this family of proteins is represented by the trimeric porins OmpC, OmpF, and PhoE. Elucidation of the structure of these proteins showed that each monomeric barrel is formed by 16 ␤-strands (5). Other outer membrane channels catalyze the specific diffusion of a particular class of nutrient and thus allow the uptake of compounds that would diffuse too slowly through the general porins (15).The E. coli maltose-specific channel protein LamB and the sucrose channel protein ScrY are the best studied of this class of channel proteins. These proteins also form trimers, and each monomer consists of 18 transmembrane ␤-strands (24). A few other specific channels are known in E. coli: the aryl-␤-

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Section: Discussionmentioning

confidence: 85%

Function and Expression of an N -Acetylneuraminic Acid-Inducible Outer Membrane Channel in Escherichia coli

et al. 2005

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“…Although both pathways similarly respond to general stress conditions in the extracytoplasmic compartment of the cell and partially overlap in their regulons, they can be distinguished by their response to specific signals. For example, E responds to misfolded outer membrane ␤-barrel proteins (7), whereas the Cpx system monitors the biogenesis of surface organelles such as pili (8). Activation of the Cpx response proceeds by means of phosphorylation of the cytoplasmic response regulator CpxR by the inner membrane histidine kinase CpxA.…”

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confidence: 99%

Surface sensing and adhesion of Escherichia coli controlled by the Cpx-signaling pathway

Otto

Silhavy

2002

Proc. Natl. Acad. Sci. U.S.A.

370

343

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Bacterial adhesion is an important initial step in biofilm formation, which may cause problems in medical, environmental, and industrial settings. In spite of obvious phenotypic differences between attached and planktonic cells, knowledge about the genetic basis for these differences and how adhesion-induced changes are mediated is limited. The Cpx two-component signal transduction pathway responds specifically to stress caused by disturbances in the cell envelope and activates genes encoding periplasmic protein folding and degrading factors. Here, we address the role of the Cpx-signaling pathway in sensing and responding to the physical change occurring during adhesion of Escherichia coli to surfaces. We present evidence that the expression of Cpx-regulated genes is induced during initial adhesion of E. coli to abiotic surfaces. This induction is specifically observed upon attachment of stationaryphase cells to hydrophobic surfaces. Moreover, surface-induced activity of the Cpx response requires NlpE, an outer membrane lipoprotein, which has previously been shown to induce the Cpx system when overproduced. The importance of a functional Cpx response during adhesion is further supported by the fact that a dramatically lower number of cells attach to the surface and dynamic cell-surface interactions as measured by a quartz crystal microbalance technique are altered when the CpxRA pathway is disrupted. The defects in adhesion exhibited by the cpxR and nlpE mutants were strikingly similar to those of wild-type cells in which protein synthesis was inhibited, suggesting that the Cpx pathway plays a key role in the regulation of adhesion-induced gene expression.biofilm formation ͉ cell envelope stress ͉ NlpE ͉ signal transduction ͉ quartz crystal microbalance B acteria often survive within biofilms, which are implicated in environmental problems and numerous infections (1). One important characteristic of biofilms is their high resistance to antibiotics, which makes the treatment of biofilm-related infections difficult. Several surface-related environmental signals, as well as surface-contact mediated by specific cell surface structures, are recognized to trigger changes that allow bacteria to undergo stable cell-surface interactions (2-5). However, it remains a challenge to identify regulatory processes critical for adhesion, the understanding of which will be useful to devise better treatments to combat biofilm formation.As the interface with the external environment, the bacterial cell envelope is directly exposed to changes in environmental conditions and is particularly sensitive to any perturbations. In Escherichia coli, stressful conditions affecting the cell envelope are perceived by two regulatory pathways, the E regulatory system and the CpxRA two-component signal transduction pathway (6). Although both pathways similarly respond to general stress conditions in the extracytoplasmic compartment of the cell and partially overlap in their regulons, they can be distinguished by their response to specific signals...

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“…Details about the precise molecular nature of Cpx-inducing signals caused by general stresses, such as alkaline pH, are not known. However, one of the functions of the Cpx regulon is to monitor pilus assembly (5) and in one such case, signaling is understood in some detail (6).…”

mentioning

confidence: 99%

The extracytoplasmic adaptor protein CpxP is degraded with substrate by DegP

Isaac

Pinkner²,

Hultgren³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

148

175

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In Escherichia coli, the CpxR͞A two-component system senses various types of extracytoplasmic stresses and responds by activating the expression of genes encoding periplasmic protein folding and trafficking factors that clear such stresses to ensure the organism's survival. The cpxP gene encodes a small, stresscombative periplasmic protein and is the most strongly induced member of the Cpx regulon. We demonstrate that the Cpx stress response suppresses the toxicity associated with two misfolded proteins derived from the P pilus of uropathogenic E. coli and that mutations in either cpxP or the gene for the periplasmic protease DegP prevent suppression by preventing the degradation of these proteins. Strikingly, the presence of a periplasmic misfolded protein substrate significantly enhances the proteolysis of CpxP by DegP. Our data suggest that CpxP functions as a periplasmic adaptor protein that is required for the effective proteolysis of a subset of misfolded substrates by the DegP protease.Escherichia coli ͉ misfolded protein ͉ periplasm ͉ regulated proteolysis

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Cpx signaling pathway monitors biogenesis and affects assembly and expression of P pili

Cited by 168 publications

References 79 publications

Function and Expression of an N -Acetylneuraminic Acid-Inducible Outer Membrane Channel in Escherichia coli

Function and Expression of an N -Acetylneuraminic Acid-Inducible Outer Membrane Channel in Escherichia coli

Surface sensing and adhesion of Escherichia coli controlled by the Cpx-signaling pathway

The extracytoplasmic adaptor protein CpxP is degraded with substrate by DegP

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