tetM

tetM is a bacterial gene that encodes a ribosomal protection protein of the Tet(M) family. It confers resistance to tetracycline antibiotics by protecting the ribosome from tetracycline binding, allowing protein synthesis to continue in the presence of the drug.

Mechanism and function: The TetM protein interacts with the ribosome in a GTP-dependent manner and dislodges tetracycline from the ribosomal A site. After GTP hydrolysis, the ribosome can resume elongation, reducing the inhibitory effect of tetracycline on translation.

Distribution and mobility: tetM is widespread among Gram-positive bacteria, including Streptococcus, Enterococcus, and Staphylococcus species. It is frequently carried on mobile genetic elements such as transposons (for example, elements related to Tn916/Tn1545), integrative and conjugative elements, and plasmids. This association with mobile elements facilitates horizontal transfer of tetracycline resistance between bacteria and across ecosystems.

Clinical and environmental relevance: The presence of tetM contributes to tetracycline resistance observed in clinical, veterinary, and environmental isolates. Detection and surveillance commonly employ PCR assays targeting tetM. The gene's mobility aids the dissemination of resistance across species and environments.

Variants and related genes: TetM is part of a broader family of ribosomal protection proteins that includes TetO, TetW, and TetQ, which share a similar mechanism but differ in host range and regulatory context. tetM determinants are often found in conjunction with other resistance genes on composite mobile elements, contributing to multidrug resistance patterns in certain strains.