title: Molecular and proteome analyses highlight the importance of the Cpx envelope stress system for acid stress and cell wall stability in Escherichia coli.
abstract: Two-component systems (TCS) play a pivotal role for bacteria in stress regulation and adaptation. However, it is not well understood how these systems are modulated to meet bacterial demands. Especially, for those TCS using an accessory protein to integrate additional signals, no data concerning the role of the accessory proteins within the coordination of the response is available. The Cpx envelope stress two-component system, composed of the sensor kinase CpxA and the response regulator CpxR, is orchestrated by the periplasmic protein CpxP which detects misfolded envelope proteins and inhibits the Cpx system in unstressed cells. Using selected reaction monitoring, we observed that the amount of CpxA and CpxR, as well as their stoichiometry, are only marginally affected, but that a 10-fold excess of CpxP over CpxA is needed to switch off the Cpx system. Moreover, the relative quantification of the proteome identified not only acid stress response as a new indirect target of the Cpx system, but also suggests a general function of the Cpx system for cell wall stability.
authors.affiliation: Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Straße 15A, Greifswald, 17475, Germany.
authors.forename: Kristin
authors.initials: K
authors.lastname: Surmann
authors.affiliation: FB 5 Microbiology, Department of Biology/Chemistry, University Osnabrück, Barbarastraße 11, Osnabrück, 49076,, Germany.
authors.forename: Emina
authors.initials: E
authors.lastname: Ćudić
authors.affiliation: Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Straße 15A, Greifswald, 17475, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Hammer
authors.affiliation: FB 5 Microbiology, Department of Biology/Chemistry, University Osnabrück, Barbarastraße 11, Osnabrück, 49076,, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Hunke
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D001426:Bacterial Proteins / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D020543:Proteome / Q000032:analysis; D040901:Proteomics / Q000379:methods; D013312:Stress, Physiological / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C491730:CpxP protein, E coli; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D020543:Proteome; C433802:RseA protein, E coli; D014157:Transcription Factors; C085504:CpxR protein, Bacteria; D011494:Protein Kinases; C490475:CpxA protein, E coli
keywords: Cpx RAP system; Escherichia coli; SRM; proteome profile; two-component system.