Integron

An integron is a gene capture system found in plasmids, chromosomes and transposons. Pieces of DNA called gene cassettes can be incorporated, expressed, and disseminated.

An integron with a large number of cassettes may be called a super-integron, as in Vibrio cholerae. A cassette may encode genes for antibiotic resistance, although most genes in integrons are uncharacterized. An integron contains an integrase related to those of a phage, an attI site for integration of cassettes, and a promoter to drive expression. An integron may appear in a plasmid or on the chromosome. An attC sequence (also called 59-be) is a repeat that flanks cassettes and enables cassettes to be integrated at the attI site, excised and undergo horizontal gene transfer.