This family comprises the C-terminal portion of proteins that belong to the TetR family of transcriptional regulators. The C terminus represents the regulatory region, and does not include the DNA binding helix-turn-helix domain. The target proteins that are repressed are involved in the transcriptional control of multi-drug efflux pumps, pathways for the biosynthesis of antibiotics, response to osmotic stress and toxic chemicals, control of catabolic pathways, differentiation processes, and pathogenicity [1]. One of the target proteins is BetI, an osmoprotectant which controls the choline-glycine betaine pathway in E.coli [2].

1: The TetR family of transcriptional repressors. Ramos JL, Martinez-Bueno M, Molina-Henares AJ, Teran W, Watanabe K, Zhang X, Gallegos MT, Brennan R, Tobes R; Microbiol Mol Biol Rev. 2005;69:326-356. PMID:15944459

2: Growth of Escherichia coli in human urine: role of salt tolerance and accumulation of glycine betaine. Kunin CM, Hua TH, Van Arsdale White L, Villarejo M; J Infect Dis. 1992;166:1311-1315. PMID:1431248