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Proteasome-independent degradation of canonical NFκB complex components by the NleC protein of pathogenic Escherichia coli

Lookup NU author(s): Dr Marie-Helene Ruchaud, Professor Brendan KennyORCiD



The NFκB transcription factor is a key component of immune and inflammatory signaling as its activation induces the expression of antimicrobial reagents, chemokines, cytokines, and anti-apoptotic factors. Many pathogens encode effector proteins that target factors regulating NFκB activity and can provide novel insights on regulatory mechanisms. Given the link of NFκB dysfunction with inflammatory diseases and some cancers, these effectors have therapeutic potential. Here, screening enteropathogenic Escherichia coli proteins for those implicated in suppressing NFκB function revealed that eGFP-NleC, unlike eGFP, strongly inhibited basal and TNFα-induced NFκB reporter activity to prevent secretion of the chemokine, IL-8. Work involving NleC variants, chemical inhibitors, and immunoprecipitation studies support NleC being a zinc metalloprotease that degrades NFκB-IκBα complexes. The findings are consistent with features between residues 33–65 recruiting NFκB for proteasomal-independent degradation by a mechanism inhibited by metalloprotease inhibitors or disruption of a consensus zinc metalloprotease motif spanning NleC residues 183–187. This raises the prospect that mammalian cells, or other pathogens, employ a similar mechanism to modulate NFκB activity. Moreover, NleC represents a novel tool for validating NFκB as a therapeutic target and, indeed, as a possible therapeutic reagent.

Publication metadata

Author(s): Mühlen S, Ruchaud-Sparagano M, Kenny B

Publication type: Article

Publication status: Published

Journal: Journal of Biological Chemistry

Year: 2011

Volume: 286

Issue: 7

Pages: 5100-5107

Print publication date: 09/12/2010

Date deposited: 10/06/2013

ISSN (print): 0021-9258

ISSN (electronic): 1083-351X

Publisher: American Society for Biochemistry and Molecular Biology, Inc.


DOI: 10.1074/jbc.M110.172254


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Funder referenceFunder name
083313Wellcome Trust
MU3050/2-1Deutsche Forschungsgemeinschaft