Transposons

Transposons are small mobile genetic elements or MGEs consisting of 700 to 40,000 base pairs.

Found in many organisms, they can move within or between the chromosomes. They can move across organisms, transferring genes between plasmids, viruses, and bacterial genomes.

Insertion sequences are the simplest transposons that encode transposase.

Inverted repeats flank this enzyme gene, which transposase recognizes for cutting and resealing DNA during transposition.

Composite transposons, along with transposase, carry additional genes, such as those for antibiotic resistance or toxin production.

Simple transposition involves the transposase moving the mobile genetic elements to a new site and duplicating the target sequence, creating flanking repeats.

In replicative transposition, the MGE remains original while a copy is inserted elsewhere.

Transposons mediate antibiotic resistance, as seen in vancomycin resistance gene transfer from Enterococcus faecalis to Staphylococcus aureus.

Transposons may drive chromosomal rearrangements, enhancing the pathogenicity in strains of Bordetella, Yersinia, and Shigella species.