title: Signal-dependent requirement for the co-activator protein RcsA in transcription of the RcsB-regulated ugd gene.
abstract: The RcsC/YojN/RcsB phosphorelay system controls gene expression in response to a variety of signals, including changes in temperature, osmolarity, and overproduction of membrane proteins. Transcription of certain RcsB-activated genes, such as the capsule synthesis cps operon, requires the co-activator protein RcsA, whereas expression of other RcsB-activated genes is RcsA-independent. We have established previously that a tolB mutation induces transcription of the Salmonella UDP-glucose dehydrogenase ugd gene in an RcsA- and RcsB-dependent manner. This induction is independent of the two-component systems PhoP/PhoQ and PmrA/PmrB, which are required for ugd expression in response to low Mg2+. We now report that the RcsC/YojN/RcsB system is activated in a pmrA mutant experiencing Fe3+ and low Mg2+, resulting in expression of both cps and ugd genes. However, whereas cps transcription remained RcsA-dependent, ugd transcription became RcsA-independent but dependent on the PhoP protein. S1 mapping experiments demonstrated that RcsA-dependent and -independent transcription of the ugd gene use the same promoter. DNase footprinting analysis identified a PhoP-binding site in the ugd promoter. Yet, PhoP-mediated ugd transcription required either the RcsC/YojN/RcsB or the PmrA/PmrB systems.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002875:Chromosomes / Q000648:ultrastructure; D003850:Deoxyribonuclease I / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D017353:Gene Deletion; D007501:Iron / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D033903:Periplasmic Proteins / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012475:Salmonella / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism; D013696:Temperature; D014157:Transcription Factors; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D033903:Periplasmic Proteins; C489568:RcsB protein, E coli; D014157:Transcription Factors; C062094:tolB protein, E coli; C074889:RcsB protein, Bacteria; C067572:RcsA protein, E coli; D007501:Iron; D003850:Deoxyribonuclease I; D015719:Single-Strand Specific DNA and RNA Endonucleases; D001616:beta-Galactosidase; D008274:Magnesium