Two Polyketides Intertwined in Complex Regulation: Posttranscriptional CsrA-Mediated Control of Colibactin and Yersiniabactin Synthesis in Escherichia coli.

Bacteria have to process several levels of gene regulation and coordination of interconnected regulatory networks to ensure the most adequate cellular response to specific growth conditions. Especially, expression of complex and costly fitness and pathogenicity-associated traits is coordinated and tightly regulated at multiple levels. We studied the interconnected regulation of the expression of the colibactin and yersiniabactin polyketide biosynthesis machineries, which are encoded by two pathogenicity islands found in many phylogroup B2 Escherichia coli isolates.

ClbR Is the Key Transcriptional Activator of Colibactin Gene Expression in Escherichia coli.

Colibactin is a nonribosomal peptide/polyketide hybrid natural product expressed by different members of the which can be correlated with induction of DNA double-strand breaks and interference with cell cycle progression in eukaryotes. Regulatory features of colibactin expression are only incompletely understood. We used strain M1/5 as a model to investigate regulation of expression of the colibactin determinant at the transcriptional level and to characterize regulatory elements located within the colibactin pathogenicity island itself.

Genetic structure and distribution of the colibactin genomic island among members of the family Enterobacteriaceae.

A genomic island encoding the biosynthesis and secretion pathway of putative hybrid nonribosomal peptide-polyketide colibactin has been recently described in Escherichia coli. Colibactin acts as a cyclomodulin and blocks the eukaryotic cell cycle. The origin and prevalence of the colibactin island among enterobacteria are unknown.

Expression analysis of the colibactin gene cluster coding for a novel polyketide in Escherichia coli.

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.

Escherichia coli induces DNA double-strand breaks in eukaryotic cells.

Transient infection of eukaryotic cells with commensal and extraintestinal pathogenic Escherichia coli of phylogenetic group B2 blocks mitosis and induces megalocytosis. This trait is linked to a widely spread genomic island that encodes giant modular nonribosomal peptide and polyketide synthases. Contact with E.

Identification of large linear plasmids in Arthrobacter spp. encoding the degradation of quinaldine to anthranilate.

Arthrobacter nitroguajacolicus Rü61a, which utilizes quinaldine as sole source of carbon and energy, was shown to contain a conjugative linear plasmid of approximately 110 kb, named pAL1. It exhibits similarities with other linear plasmids from Actinomycetales in that it has proteins covalently attached to its 5' ends. Southern hybridization with probes for the genes encoding quinaldine 4-oxidase and N-acetylanthranilate amidase indicated that pAL1 contains the gene cluster encoding the degradation of quinaldine to anthranilate.