Group IIC Intron with an Unusual Target of Integration in Enterobacter cloacae

A potential role of group IIC-attC introns in integron gene cassette formation, that is, the way in which they could provide the attC sequence essential for recombination, has been proposed. Group IIC introns usually target the attC site of gene cassettes and more specifically their inverse core. He...

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Bibliographic Details
Published in:Journal of Bacteriology 2012, Vol.194 (1), p.150-160
Main Authors: Rodríguez-Martínez, José-Manuel, Nordmann, Patrice, Poirel, Laurent
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Bacterial Proteins - genetics
Bacterial Proteins - metabolism
Bacteriology
beta-lactamase
Biological and medical sciences
Enterobacter cloacae
Enterobacter cloacae - classification
Enterobacter cloacae - genetics
Enterobacter cloacae - metabolism
Escherichia coli
Fundamental and applied biological sciences. Psychology
Gene expression
Gene Expression Regulation, Bacterial - physiology
genes
Genetic recombination
Genome, Bacterial
Gram-negative bacteria
Integrons - genetics
introns
Introns - physiology
Microbiology
Miscellaneous
Molecular Sequence Data
Mutagenesis, Site-Directed
Phylogeny
Real-Time Polymerase Chain Reaction
Reverse Transcriptase Polymerase Chain Reaction
Ribonucleic acid
RNA
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Summary:A potential role of group IIC-attC introns in integron gene cassette formation, that is, the way in which they could provide the attC sequence essential for recombination, has been proposed. Group IIC introns usually target the attC site of gene cassettes and more specifically their inverse core. Here we characterized a novel group IIC intron targeting the core site of the aadA1 gene cassette attC site (aadA1-qacEΔ1 gene cassette junction) from enterobacterial isolates. Intron mobility (retrohoming) was analyzed using a two-plasmid assay performed in Escherichia coli. Intron mobility assays confirmed the mobilization-integration of the group II intron into the core site of the aadA2, blaVIM-2, blaCARB-2, aac(6')-Ib, dfrXVb, arr2, cmlA4, and aadB gene cassettes but not into the attI site. This mobility was dependent on maturase activity. Reverse transcriptase PCR showed that this intron was transcriptionally active, and an intermediate circular form was detected by inverse PCR. This element was linked to the blaVEB-1 extended-spectrum β-lactamase gene in a high number of enterobacterial isolates. A phylogenetic tree showed that the identified element was located in a branch separate from group IIC-attC introns, being an IIC intron possessing the ability to integrate using the core site of the attC sites as target.
ISSN:0021-9193
1098-5530
1067-8832
DOI:10.1128/JB.05786-11