Integrons: an Antibiotic Resistance Gene Capture and Expression System
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Marie-Cécile Ploy
Abstract
Bacteria can transfer genetic information to provide themselves with protection against most antibiotics. The acquisition of resistance gene arrays involves genetic mobile elements like plasmids and transposons. Another class of genetic structures, termed integrons, have been described and contain one or more gene cassettes located at a specific site. Integrons are defined by an intI gene encoding an integrase, a recombination site attI and a strong promoter. At least six classes of integrons have been determined according to their intI gene. Classes 1, 2 and 3 are the most studied and are largely implicated in the dissemination of antibiotic resistance. A gene cassette includes an open reading frame and, at the 3′-end, a recombination site attC. Integration or excision of cassettes occur by a site-specific recombination mechanism catalyzed by the integrase. However, insertion can occur, albeit rarely, at non-specific sites leading to a stable situation for the cassette. Cassettes are transcribed from the common promoter located in the 5′-conserved segment and expression of distal genes is reduced by the presence of upstream cassettes. Most gene cassettes encode antibiotic resistant determinants but antiseptic resistant genes have also been described. Integrons seem to have a major role in the spread of multidrug resistance in Gram-negative bacteria but integrons in Gram-positive bacteria were described recently. Moreover, the finding of super-integrons with gene-cassettes coding for other determinants (biochemical functions, virulence factors) in Vibrio isolates dating from 1888 suggests the likely implication of this multi-component cassette-integron system in bacterial genome evolution before the antibiotic era and to a greater extent than initially believed.
Copyright © 2000 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Integrons: an Antibiotic Resistance Gene Capture and Expression System
- Levels of C-Telopeptide Fragments of Collagen Type I Enable the Monitoring and Early Adjustment of Clodronate Therapy in Patients with Postmenopausal Osteoporosis
- Probable Involvement of Cathepsin D in the Degradation of β2-Microglobulin in Acidic Urine
- Autoantibodies against Oxidized Low-Density Lipoprotein Correlate with Achilles Tendon Xanthomas
- Regulation of the Hepatic Endothelin System in Advanced Biliary Fibrosis in Rats
- Determination of Plasma Methoxyamines
- Stability of Brain Natriuretic Peptide (BNP) in Human Whole Blood and Plasma
- Effect of Short- and Long-Term Storage on Human Serum and Recombinant Apolipoprotein E Concentration
- Comparison of Laboratory Parameters as Risk Factors for the Presence and the Extent of Coronary or Carotid Atherosclerosis: the Significance of Apolipoprotein B to Apolipoprotein AII Ratio
- The Effect of a Gender Difference in the Apolipoprotein E Gene DNA Polymorphism on Serum Lipid Levels in a Serbian Healthy Population
- A Model for Setting Analytical Quality Specifications and Design of Control for Measurements on the Ordinal Scale
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- Concordance of Eight Kits for Antithyroid Peroxidase Autoantibodies Determination
- Evaluation of a Point-of-Care System for Quantitative Determination of Troponin T and Myoglobin
- The Maillard Reaction in Foods and Medicine. By John OBrien, Harry E. Nursden, M. James, C. Crabbe and Jennifer M. Ames, editors
- Apoptosis and Inflammation. By J.D. Winkler, editor
