Tn916Tn1545

Tn916Tn1545 refers to transposable elements related to the Tn916/Tn1545 family of conjugative transposons found in Gram-positive bacteria, notably Enterococcus and Streptococcus species. These elements are self-transmissible mobile genetic elements that can move within a genome and between bacteria by conjugation. They are capable of excising from the chromosome to form a circular intermediate, which facilitates transfer to recipient cells and subsequent integration at new chromosomal sites.

A defining feature of the Tn916/Tn1545 family is the carriage of tetracycline resistance genes, primarily tet(M), which encode a ribosome protection protein that confers resistance to tetracycline antibiotics. The transposons also carry core genes responsible for integration, excision, and transfer, and their regulatory modules coordinate these processes. While Tn916 and Tn1545 share a common mechanism and cargo, they differ in internal gene organization and size; recombinants or hybrid elements combining features of both have been observed, reflecting ongoing genetic shuffling within the family.

Lifecycle and transfer are inducible under certain conditions, and the elements can spread resistance determinants among bacterial populations via horizontal gene transfer. The ability of these transposons to move as circular intermediates and to integrate into diverse chromosomal locations contributes to their efficiency as vehicles for antibiotic resistance.

Impact and significance include their role as major facilitators of tetracycline resistance in clinically relevant bacteria, influencing patterns of resistance in healthcare and environmental settings. Research on Tn916/Tn1545-like elements informs understanding of horizontal gene transfer and the evolution of multi-resistance determinants.

See also: conjugative transposon, tet(M), antibiotic resistance.