title: The sigma(E) and the Cpx signal transduction systems control the synthesis of periplasmic protein-folding enzymes in Escherichia coli.
abstract: In Escherichia coli, the heat shock-inducible sigma-factor sigma(E) and the Cpx two-component signal transduction system are both attuned to extracytoplasmic stimuli. For example, sigma(E) activity rises in response to the overproduction of various outer-membrane proteins. Similarly, the activity of the Cpx signal transduction pathway, which consists of an inner-membrane sensor (CpxA) and a cognate response regulator (CpxR), is stimulated by overproduction of the outer-membrane lipoprotein, NlpE. In response to these extracytoplasmic stimuli, sigma(E) and CpxA/CpxR stimulate the transcription of degP, which encodes a periplasmic protease. This suggests that CpxA/CpxR and sigma(E) both mediate protein turnover within the bacterial envelope. Here, we show that CpxA/CpxR and sigma(E) also control the synthesis of periplasmic enzymes that can facilitate protein-folding reactions. Specifically, sigma(E) controls transcription of fkpA, which specifies a periplasmic peptidyl-prolyl cis/trans isomerase. Similarly, the Cpx system controls transcription of the dsbA locus, which encodes a periplasmic enzyme required for efficient disulfide bond formation in several extracytoplasmic proteins. Taken together, these results indicate that sigma(E) and CpxA/CpxR are involved in regulating both protein-turnover and protein-folding activities within the bacterial envelope.
authors.affiliation: Department of Molecular Biology, Princeton University, New Jersey 08544, USA.
authors.forename: P N
authors.initials: PN
authors.lastname: Danese
authors.forename: T J
authors.initials: TJ
authors.lastname: Silhavy
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis / Q000737:chemistry; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D020104:Immunophilins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase; D017510:Protein Folding; D011494:Protein Kinases; D018085:Regulon; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C063202:sporulation-specific sigma factors; C085504:CpxR protein, Bacteria; D011494:Protein Kinases; C490475:CpxA protein, E coli; C092472:CpxA protein, bacteria; D020104:Immunophilins; D019696:Peptidylprolyl Isomerase; C068254:FkpA protein, E coli