This is the C-terminal tetracyclin repressor domain found in bacteria. Family members include TetR family transcriptional regulators Rv3249c and Rv1816 found in Mycobacterium tuberculosis. Palmitic acid (a fatty acid) and isopropyl laurate (a fatty acid ester), were identified as binding ligands to Rv3249c and Rv1816 respectively. Similar to other TetR family regulators, these proteins are alpha-helical dimeric proteins consisting of a smaller N-terminal DNA-binding domain and a larger C-terminal regulatory domain [1].

1: Structural Basis for the Regulation of the MmpL Transporters of Mycobacterium tuberculosis. Delmar JA, Chou TH, Wright CC, Licon MH, Doh JK, Radhakrishnan A, Kumar N, Lei HT, Bolla JR, Rajashankar KR, Su CC, Purdy GE, Yu EW; J Biol Chem. 2015;290:28559-28574. PMID:26396194