title: The superintegron integrase and the cassette promoters are co-regulated in Vibrio cholerae.
abstract: Chromosome 2 of Vibrio cholerae carries a chromosomal superintegron, composed of an integrase, a cassette integration site (attI) and an array of mostly promoterless gene cassettes. We determined the precise location of the promoter, Pc, which drives the transcription of the first cassettes of the V. cholerae superintegron. We found that cassette mRNA starts 65 bp upstream of the attI site, so that the inversely oriented promoters Pc and Pint (integrase promoter) partly overlap, allowing for their potential co-regulation. Pint was previously shown to be induced during the SOS response and is further controlled by the catabolite repression cAMP-CRP complex. We found that cassette expression from Pc was also controlled by the cAMP-CRP complex, but is not part of the SOS regulon. Pint and Pc promoters were both found to be induced in rich medium, at high temperature, high salinity and at the end of exponential growth phase, although at very different levels and independently of sigma factor RpoS. All these results show that expression from the integrase and cassette promoters can take place at the same time, thus leading to coordinated excisions and integrations within the superintegron and potentially coupling cassette shuffling to immediate selective advantage.
authors.affiliation: Institut Pasteur, Unité de Plasticité du Génome Bactérien, Département Génomes et Génétique, Paris, France; CNRS, UMR 3525, Paris, France.
authors.forename: Evelyne
authors.initials: E
authors.lastname: Krin
authors.affiliation: Institut Pasteur, Unité de Plasticité du Génome Bactérien, Département Génomes et Génétique, Paris, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Cambray
authors.affiliation: Institut Pasteur, Unité de Plasticité du Génome Bactérien, Département Génomes et Génétique, Paris, France; CNRS, UMR 3525, Paris, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Mazel
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001483:Base Sequence; D057465:Catabolite Repression / Q000187:drug effects / Q000235:genetics; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D019426:Integrases / Q000378:metabolism*; D032023:Integrons / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D013014:SOS Response, Genetics / Q000187:drug effects / Q000235:genetics; D012808:Sigma Factor / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D024363:Transcription Initiation Site; D014734:Vibrio cholerae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D012808:Sigma Factor; D012965:Sodium Chloride; D000242:Cyclic AMP; D019426:Integrases