title: Expression analysis of the colibactin gene cluster coding for a novel polyketide in Escherichia coli.
abstract: The recently described hybrid nonribosomal peptide-polyketide colibactin, found in various Escherichia coli strains, invokes a cytopathic effect in HeLa cells upon cocultivation with these bacteria. However, not much is known so far about the transcriptional organization of the colibactin genes (clb) or the regulation of their transcription. Here, the operon structure of the colibactin gene cluster of E. coli strain Nissle 1917 was investigated by means of reverse transcriptase (RT)-PCR and seven transcripts were found of which four are transcribed polycistronically. The polycistrons comprise the genes clbC to clbG, clbI to clbN, clbO to clbP, and clbR to clbA and span 6.3, 23.3, 3.9, and 0.9 kb, respectively. Furthermore, transcript levels for different cultivation conditions were determined by RT-PCR of the whole cluster as well as by luciferase reporter gene assays of the genes clbA, clbB, clbQ, and clbR. RT-PCR revealed an overall increased transcription in shaking cultures as well as of the genes clbA to clbH in general. Luciferase reporter gene fusions indicated an influence of the carbon source on clb gene expression.
authors: Institut für Molekulare Infektionsbiologie, Universität Würzburg, Würzburg, Germany.
authors: Stefan
authors: S
authors: Homburg
authors: Eric
authors: E
authors: Oswald
authors: Jörg
authors: J
authors: Hacker
authors: Ulrich
authors: U
authors: Dobrindt
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D017930:Genes, Reporter; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D018942:Macrolides / Q000378:metabolism*; D005810:Multigene Family; D046908:Peptide Biosynthesis, Nucleic Acid-Independent; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism*; D048630:Polyketide Synthases / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D029968:Escherichia coli Proteins; D018942:Macrolides; D048630:Polyketide Synthases; D008156:Luciferases; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase