TetAB

TetAB refers to a tetracycline resistance gene locus found in bacteria, typically comprising two genes, tetA and tetB, that encode tetracycline efflux pumps. The tetAB arrangement is commonly carried on plasmids or transposons, enabling horizontal transfer between species. In some isolates a single tetA or tetB gene may occur, but the paired tetAB configuration is associated with broader or higher-level resistance.

Mechanism and regulation: The TetA and TetB proteins are membrane transporters belonging to the major facilitator superfamily. They function as efflux pumps, using the proton motive force to export tetracycline from the cell, thereby reducing intracellular drug concentration and allowing growth in the presence of tetracycline. Expression is often controlled by TetR family regulators, which repress transcription in the absence of tetracycline and derepress in its presence.

Distribution and impact: tetAB is widespread in Gram-negative and Gram-positive bacteria, detected in clinical, agricultural, and environmental isolates. The genes are commonly linked to mobile genetic elements, facilitating dissemination of tetracycline resistance in microbial communities.

Clinical significance and research: The tetAB locus is a classic example of acquired resistance to tetracyclines and is used in surveillance of antimicrobial resistance. Studies focus on regulation of expression, pump mechanism, genetic context, and the potential for co-selection with other resistance determinants.

See also: tetracycline resistance, tet genes, efflux pumps, TetR regulators.