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Title: Integron  
Author: World Heritage Encyclopedia
Language: English
Subject: SRNA-Xcc1, Horizontal gene transfer, Virology, Transposable element, Enzymes
Publisher: World Heritage Encyclopedia


Integrons are genetic units characterized by their ability to capture and incorporate gene cassettes by site-specific recombination.


  • Discovery 1
  • Structure 2
    • Gene Cassettes 2.1
  • Occurrence 3
  • Terminology 4
  • References 5
  • Further reading 6
  • External links 7


They were initially discovered in relation to antibiotic resistance.[1]


An integron is minimally composed of:[2][3]

  • a gene encoding for a site-specific recombinase: intI, belonging to the integrase family
  • a proximal recombination site: attI, which is recognized by the integrase[4] and at which gene cassettes may be inserted
  • a promoter: Pc, which directs transcription of cassette-encoded genes

Gene Cassettes

Additionally, an integron will usually contain one or more gene cassettes that have been incorporated into it. The gene cassettes may encode genes for antibiotic resistance, although most genes in integrons are uncharacterized. 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.


Integrons may be found as part of mobile genetic elements such as plasmids and transposons. Integrons can also be found in chromosomes.


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.[5][6] 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.[5]


  1. ^ Integrons: agents of bacterial evolution (Mazel 2006), Nature Reviews Microbiology 4, 608-620 | doi:10.1038/nrmicro1462
  2. ^ Kovalevskaya, N. P. (2002). Molecular Biology 36 (2): 196.  
  3. ^ Hall R, Collis C, Kim M, Partridge S, Recchia G, Stokes H (1999) Mobile gene cassettes and integrons in evolution. Ann. New York Acad. Sci. 870:68–80.
  4. ^ 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.  
  5. ^ a b Hall, R. M.; Stokes, HW (2004). "Integrons or super integrons?". Microbiology 150 (Pt 1): 3–4.  
  6. ^ Mazel, D.; Dychinco, B; Webb, VA; Davies, J (1998). "A Distinctive Class of Integron in the Vibrio cholerae Genome". Science 280 (5363): 605–8.  
  • Medical terms

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

External links

  • INTEGRALL - The Integron Database
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