title: Expression of different bacterial cytotoxins is controlled by two global transcription factors, CRP and Fis, that co-operate in a shared-recruitment mechanism.
abstract: Pet is a cytotoxic autotransporter protein secreted by the pathogenic enteroaggregative Escherichia coli strain 042. Expression of Pet is co-dependent on two global transcription regulators: CRP (cyclic AMP receptor protein) and Fis (factor for inversion stimulation). At the pet promoter CRP binds to a single site centred at position -40.5 upstream of the start site for transcription. Due to the suboptimal positioning of this site, CRP alone activates transcription poorly and requires Fis to bind upstream to promote full activation. Here, we show that CRP and Fis control the expression of other important autotransporter toxins, namely Sat from uropathogenic E. coli (UPEC) and SigA from Shigella sonnei, and that this regulation has been conserved in different pathogens. Furthermore, we investigate the mechanism of Fis-mediated co-activation, exploiting a series of semi-synthetic promoters, with similar architecture to the pet promoter. We show that, when bound at position -40.5, CRP recruits RNA polymerase inefficiently and that Fis compensates by aiding polymerase recruitment through a direct protein-protein interaction. We demonstrate that other suitably positioned upstream transcription factors, which directly recruit RNA polymerase, can also compensate for the inappropriate positioning of CRP. We propose that this is a simple 'shared-recruitment' mechanism, by which co-dependence of promoters on two transcription factors could evolve.
authors.affiliation: *Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Amanda E
authors.initials: AE
authors.lastname: Rossiter
authors.affiliation: *Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Rita E
authors.initials: RE
authors.lastname: Godfrey
authors.affiliation: *Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Jack A
authors.initials: JA
authors.lastname: Connolly
authors.affiliation: *Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Stephen J W
authors.initials: SJ
authors.lastname: Busby
authors.affiliation: *Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Henderson
authors.affiliation: *Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Browning
mesh_terms: D024506:5' Flanking Region; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D002373:Cyclic AMP Receptor Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004768:Enterotoxins / Q000235:genetics / Q000378:metabolism; D048168:Escherichia coli K12 / Q000201:enzymology / Q000378:metabolism / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D035021:Factor For Inversion Stimulation Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008958:Models, Molecular; D009154:Mutation; D011401:Promoter Regions, Genetic; D054730:Protein Interaction Domains and Motifs; D020218:Response Elements; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D012764:Shigella sonnei / Q000201:enzymology / Q000378:metabolism / Q000472:pathogenicity; D012808:Sigma Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D056689:Uropathogenic Escherichia coli / Q000201:enzymology / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D002373:Cyclic AMP Receptor Protein; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; C501034:Fis protein, E coli; D012808:Sigma Factor; C481662:crp protein, E coli; C506813:secreted autotransporter toxin, E coli; D012321:DNA-Directed RNA Polymerases; C530786:Pet protein, E coli; D012697:Serine Endopeptidases