title: Effects of DNA supercoiling and topoisomerases on the expression of genes coding for F165(1), a P-like fimbriae.
abstract: Pathogenic Escherichia coli 4787 (O115:KV165) causes septicemia in pigs and expresses the fimbriae F165(1) encoded by the foo operon that belongs to the P fimbrial family. fooI and fooB, encoding specific foo regulators, are divergently transcribed; their intergenic region is responsible for the regulation of foo expression. The role of global and local supercoiling (transcription-induced supercoiling within the intergenic region) on the regulation of foo expression was investigated. Expression of fooB was significantly altered when global negative supercoiling was reduced by a mutation that decreases DNA gyrase activity. Deletion of the topA gene, encoding for topoisomerase I that relaxes local negative supercoiling, further reduced fooB expression. This suggests that both global and local supercoiling can significantly affect fooB expression. Moreover, FooI, a positive regulator of fooB expression, has no effect on fooB expression in the topA null mutant. This study showed that divergent transcription from a strong promoter can significantly enhance fooB expression and compensate for the absence of FooI in a wild-type strain.
authors.affiliation: Département de pathologie et microbiologie, Université de Montréal, St-Hyacinthe, QC, Canada.
authors.forename: Marie-Catherine
authors.initials: MC
authors.lastname: Tessier
authors.forename: Richard
authors.initials: R
authors.lastname: Graveline
authors.forename: Cécile
authors.initials: C
authors.lastname: Crost
authors.forename: Julie Annick
authors.initials: JA
authors.lastname: Desabrais
authors.forename: Christine
authors.initials: C
authors.lastname: Martin
authors.forename: Marc
authors.initials: M
authors.lastname: Drolet
authors.forename: Josée
authors.initials: J
authors.lastname: Harel
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D019175:DNA Methylation; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D004278:DNA, Superhelical / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D010957:Plasmids; D014158:Transcription, Genetic
chemical_list: D000942:Antigens, Bacterial; D004278:DNA, Superhelical; D029968:Escherichia coli Proteins; C088773:F165 protein, E coli; D036781:Fimbriae Proteins; D004264:DNA Topoisomerases, Type I