Integron
An integron is a two component gene capture and dissemination system, initially discovered in relation to antibiotic resistance, and which is found in plasmids, chromosomes and transposons. The first component consists of a gene encoding a site specific recombinase along with a specific site for recombination, while the second component comprises fragments of DNA called gene cassettes which can be incorporated or shuffled.
A cassette may encode genes for antibiotic resistance, although most genes in integrons are uncharacterized. An integron contains an integrase (int1) related to those of a phage, followed by an attI site for integration of cassettes and recognition of the integrase,[1] 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.
A functional integron "platform" requires[2]:
- an integrase: intI, a tyrosine recombinase responsible for incorporation into the genome
- a proximal recombination site: attI, which acts as the locus for reincorporation to the genome. It combines with a attC site at the insertion site.
The term super-integron was first applied in 1998 (but without definition) to the integron with a long cassette array on the small chromosome of Vibrio cholerae.[3][4] The term has since been used for integrons of various cassette array lengths or for integrons on bacterial chromosomes (versus, for example, plasmids). Use of "super-integron" is now discouraged since its meaning is unclear.[3]
[edit] References
- ^ Hall, RM; Collis, CM (1995). "Mobile gene cassettes and integrons: Capture and spread of genes by site-specific recombination". Molecular microbiology 15 (4): 593–600. PMID 7783631.
- ^ Kovalevskaya, N. P. (2002). Molecular Biology 36 (2): 196. doi:10.1023/A:1015361704475.
- ^ a b Hall, R. M.; Stokes, HW (2004). "Integrons or super integrons?". Microbiology 150 (Pt 1): 3–4. doi:10.1099/mic.0.26854-0. PMID 14702391.
- ^ Mazel, D.; Dychinco, B; Webb, VA; Davies, J (1998). "A Distinctive Class of Integron in the Vibrio cholerae Genome". Science 280 (5363): 605–8. doi:10.1126/science.280.5363.605. PMID 9554855.
[edit] Further reading
- Journal of Bacteriology, June 2002, p. 3017-3026, Vol. 184, No. 11 article Characterization of the Class 3 Integron and the Site-Specific Recombination System It Determines
- NCBI Antimicrob Agents Chemother. 1998 Dec;42(12):3053-8. article Class 1 integron-borne multiple-antibiotic resistance carried by IncFI and IncL/M plasmids in Salmonella enterica serotype typhimurium
- Nature Reviews Microbiology 4, 608-620. Mazel, D. Integrons: agents of bacterial evolution
[edit] External links
- INTEGRALL The Integron Database
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