title: Positive control of the two-component RcsC/B signal transduction network by DjlA: a member of the DnaJ family of molecular chaperones in Escherichia coli.
abstract: The membrane-anchored DjIA protein represents the third member of the DnaJ 'J-domain' family of Escherichia coli that includes DnaJ and CbpA. DjIA possesses a J-domain at its extreme C-terminus but shares no additional homology with DnaJ. Our genetic analysis suggests that DjIA acts in concert with the RcsB/C two-component signal transduction system to augment induction of the cps (capsular polysaccharide) operon and synthesis of colanic acid mucoid capsule. The DjIA J-domain is essential for the observed stimulation of this pathway as deletion, or introduction of the mutation H233Q, within the highly conserved HPD tripeptide abolished all inducing activity. Deletion of the transmembrane anchor sequence also abolished all inducing activity. djIA is not an essential gene under all conditions tested, nor is it essential for mucoid capsule biosynthesis; however, strong overexpression leads to rapid loss of cell viability suggesting that the gene is normally tightly regulated. Northern analysis revealed that djIA message was extremely unstable but could be induced or stabilized in response to cold shock. The activation of the cps operon by DjIA is dependent upon both DnaK(Hsp70) and GrpE, and therefore we propose a role for DjIA, together with this chaperone machine, as a novel regulator of a two-component histidine kinase signal transduction pathway.
authors.affiliation: Département de Biochimie Médicale, Université de Genève, Switzerland. William.Kelley@medecine.unige.ch
authors.forename: W L
authors.initials: WL
authors.lastname: Kelley
authors.forename: C
authors.initials: C
authors.lastname: Georgopoulos
mesh_terms: D000595:Amino Acid Sequence; D016667:Bacterial Capsules / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002470:Cell Survival / Q000235:genetics / Q000502:physiology; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003080:Cold Temperature; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D005822:Genetic Vectors / Q000235:genetics; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000502:physiology; D006360:Heat-Shock Proteins / Q000235:genetics / Q000502:physiology; D018832:Molecular Chaperones / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D009154:Mutation / Q000235:genetics / Q000502:physiology; D010749:Phosphoprotein Phosphatases; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology; D011494:Protein Kinases; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D013696:Temperature; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C494634:DjlA protein, E coli; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; C068113:GrpE protein, Bacteria; C489400:GrpE protein, E coli; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; D012333:RNA, Messenger; C489568:RcsB protein, E coli; D014157:Transcription Factors; C489728:rcsC protein, E coli; C074889:RcsB protein, Bacteria; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; C063842:dnaK protein, E coli