regulates tet(A) mutant efflux regulatory protein conferring antibiotic resistance protein(s) and two-component regulatory system modulating antibiotic efflux tetR TetR is the repressor of the tetracycline resistance element; its N-terminal region forms a helix-turn-helix structure and binds DNA. Binding of tetracycline to TetR reduces the repressor affinity for the tetracycline resistance gene (tetA) promoter operator sites. Mutations arise within tetR results in lower affinity for tetracyclin. antibiotic_resistance tetR ARO:3003479