title: The Cpx envelope stress response affects expression of the type IV bundle-forming pili of enteropathogenic Escherichia coli.
abstract: The Cpx envelope stress response mediates adaptation to potentially lethal envelope stresses in Escherichia coli. The two-component regulatory system consisting of the sensor kinase CpxA and the response regulator CpxR senses and mediates adaptation to envelope insults believed to result in protein misfolding in this compartment. Recently, a role was demonstrated for the Cpx response in the biogenesis of P pili, attachment organelles expressed by uropathogenic E. coli. CpxA senses misfolded P pilus assembly intermediates and initiates increased expression of both assembly and regulatory factors required for P pilus elaboration. In this report, we demonstrate that the Cpx response is also involved in the expression of the type IV bundle-forming pili of enteropathogenic E. coli (EPEC). Bundle-forming pili were not elaborated from an exogenous promoter in E. coli laboratory strain MC4100 unless the Cpx pathway was constitutively activated. Further, an EPEC cpxR mutant synthesized diminished levels of bundle-forming pili and was significantly affected in adherence to epithelial cells. Since type IV bundle-forming pili are very different from chaperone-usher-type P pili in both form and biogenesis, our results suggest that the Cpx envelope stress response plays a general role in the expression of envelope-localized organelles with diverse structures and assembly pathways.
authors.affiliation: Department of Biological Sciences, CW405A Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E9.
authors.forename: Anna Z
authors.initials: AZ
authors.lastname: Nevesinjac
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Raivio
mesh_terms: D000222:Adaptation, Physiological; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000502:physiology*; D002460:Cell Line; D002473:Cell Wall / Q000378:metabolism; D004847:Epithelial Cells / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000502:physiology*; D010861:Fimbriae, Bacterial / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D006801:Humans; D016254:Mutagenesis, Insertional; D009154:Mutation; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000502:physiology*; D021381:Protein Transport; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C085504:CpxR protein, Bacteria; D011494:Protein Kinases; C490475:CpxA protein, E coli