title: Point mutations in the transmembrane domain of DjlA, a membrane-linked DnaJ-like protein, abolish its function in promoting colanic acid production via the Rcs signal transduction pathway.
abstract: DjIA is a novel DnaJ-like protein localized to the inner membrane of Escherichia coli through the single transmembrane domain (TMD) found at the N-terminus. The overproduction of DjIA activates expression of the cps operon, controlling synthesis and export of the extracellular polysaccharide colanic acid via the Rcs/B two-component signal transduction pathway. We now show that both the TMD and the J-region are essential for the induction of cps expression observed with the overproduction of DjIA. Furthermore, we describe the isolation and characterization of different point mutations in the TMD that completely or partially block the induction of cps expression associated with overproduction of DjIA. These mutations were shown not to affect the localization, stability or topology of the mutant DjIA proteins. We propose that these mutations are affecting specific interactions between the TMD of DjIA and its substrate protein(s), for example RcsC, the membrane sensor kinase partner of the Rcs/B signal transduction pathway.
authors.affiliation: Institut de Génétique et Microbiologie, URA 1354, Universite Paris-Sud, Orsay, France.
authors.forename: D J
authors.initials: DJ
authors.lastname: Clarke
authors.forename: I B
authors.initials: IB
authors.lastname: Holland
authors.forename: A
authors.initials: A
authors.lastname: Jacq
mesh_terms: D000907:Antibodies, Bacterial / Q000032:analysis / Q000235:genetics; D016667:Bacterial Capsules / Q000235:genetics; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D001665:Binding Sites / Q000235:genetics; D002462:Cell Membrane / Q000737:chemistry / Q000235:genetics; D003470:Culture Media; D003593:Cytoplasm / Q000737:chemistry / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology / Q000502:physiology; D029968:Escherichia coli Proteins; D015870:Gene Expression / Q000235:genetics / Q000502:physiology; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D009097:Multienzyme Complexes; D009154:Mutation; D010749:Phosphoprotein Phosphatases; D017354:Point Mutation / Q000235:genetics / Q000502:physiology*; D011134:Polysaccharides / Q000096:biosynthesis*; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011494:Protein Kinases; D011994:Recombinant Proteins / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D003470:Culture Media; D004269:DNA, Bacterial; C494634:DjlA protein, E coli; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D011134:Polysaccharides; D011135:Polysaccharides, Bacterial; C489568:RcsB protein, E coli; D011994:Recombinant Proteins; D014157:Transcription Factors; C489728:rcsC protein, E coli; C074889:RcsB protein, Bacteria; C004275:colanic acid; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases