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| Subject Categories: Genome Stability & Dynamics |
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| The EMBO Journal
(2005) 24, 4356–4367, doi:10.1038/sj.emboj.7600898 Published online 8 December 2005 |
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| Integron cassette insertion: a recombination process involving a folded single strand substrate |
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| Marie Bouvier1, Gaëlle Demarre1 and Didier Mazel |
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Unité Postulante Plasticité du Génome Bactérien, CNRS URA 2171, Institut Pasteur, Paris, France To whom correspondence should be addressed Didier Mazel, Unité Postulante Plasticité du Génome Bactérien, CNRS URA 2171, Institut Pasteur, 25 rue du Dr Roux, 75724, Paris, France. Tel.: +33 1 4061 3284; Fax: +33 1 4568 8834; E-mail: mazel@pasteur.fr 1 These authors contributed equally to this work Received 12 August 2005; Accepted 11 November 2005; Published online 8 December 2005. |
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| Abstract |
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| Integrons play a major role in the dissemination of antibiotic resistance genes among Gram-negative pathogens. Integron gene cassettes form circular intermediates carrying a recombination site, attC, and insert into an integron platform at a second site, attI, in a reaction catalyzed by an integron-specific integrase IntI. The IntI1 integron integrase preferentially binds to the 'bottom strand' of single-stranded attC. We have addressed the insertion mechanism in vivo using a recombination assay exploiting plasmid conjugation to exclusively deliver either the top or bottom strand of different integrase recombination substrates. Recombination of a single-stranded attC site with an attI site was 1000-fold higher for one strand than for the other. Conversely, following conjugative transfer of either attI strand, recombination with attC is highly unfavorable. These results and those obtained using mutations within a putative attC stem-and-loop strongly support a novel integron cassette insertion model in which the single bottom attC strand adopts a folded structure generating a double strand recombination site. Thus, recombination would insert a single strand cassette, which must be subsequently processed. |
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| Keywords: antibiotic resistance, DNA, evolution, lateral gene transfer, tyrosine recombinase |
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Top of page MORE ARTICLES LIKE THISThese links to content published by NPG are automatically generated RESEARCHNature Reviews Microbiology Correspondence (01 Feb 2007) Nature Reviews Microbiology Correspondence (01 Dec 2006) The ISME Journal Original Article The ISME Journal Original Article |
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