integronides

Integronides are a class of bacterial mobile genetic elements that play a significant role in the dissemination of antibiotic resistance genes. They are characterized by the presence of a specific DNA sequence encoding an integrase enzyme, which facilitates the acquisition and integration of gene cassettes. These gene cassettes, typically small DNA fragments containing open reading frames, are often antibiotic resistance genes. The integrase enzyme recognizes specific recombination sites within the integron and the gene cassette, enabling their insertion into the integron's platform.

Integrons are a type of genetic structure that can capture and express gene cassettes. They consist of a conserved integrase gene and a recognition site for cassette integration, known as the attI site. The integrase protein, usually an IntI protein, catalyzes the site-specific recombination between the attI site and a complementary site on the incoming gene cassette, the attC site. Once integrated, these gene cassettes are transcribed from promoters within the integron or from their own promoters.

The ability of integrons to acquire and mobilize multiple gene cassettes makes them powerful vehicles for the spread of multidrug resistance. A single integron can accumulate several resistance genes, conferring resistance to a wide range of antibiotics on the host bacterium. These integrons are often found on plasmids or transposons, further enhancing their mobility within and between bacterial populations. The study of integronides is crucial for understanding the evolution and spread of antibiotic resistance, which poses a significant threat to public health.