An FAD-requiring monooxygenase active on tetracycline antibiotic and some of its derivatives, which leads to their inactivation (PubMed:26097034). Expression in E.coli confers high resistance to tetracycline and oxytetracycline, does not confer resistance to minocycline or tigecycline. Degrades tetracycline and oxytetracycline; the reaction requires NADPH (PubMed:26097034). Degrades and confers resistance to chlortetracycline (PubMed:28481346). a tetracycline + H(+) + NADPH + O2 = a (1S,10aS)-3-(CONH2)-1-(Me2N)-3,3a,4,6-(HO)4-2,5-dioxo-1H,10aH,11H,11aH-cyclopenta[b]anthracene + CO + H2O + NADP(+) 7-chlorotetracycline + H(+) + NADPH + O2 = (1S,10S,10aS)-3-(CONH2)-9-Cl-1-(Me2N)-3,3a,4,10-(HO)4-10-Me-2,5-dioxo-1H,10aH,11H,11aH-cyclopenta[b]anthracen-6-olate + CO + H2O + NADP(+) Binds 1 FAD per subunit; it is seen bound in two conformations. Inhibited by anhydrotetracycline. kcat for tetracycline is 4.3 min(-1), kcat for chlortetracycline is 3.5 min(-1). Consists of an N-terminal FAD-binding domain with a Rossman fold, a substrate-binding domain and a C-terminal helix that bridges the 2 domains close to the antibiotic-binding site. This last helix is flexible, is not found in TetX of Bacteroides species, and may contribute to their different substrate specificities (PubMed:28481346). Binds chlortetracycline in a different orientation (180 degrees rotated on its long axis) compared to tetracycline substrate binding to TetX; binding of chlortetracycline alters conformation FAD and the last helix (PubMed:28481346). Isolated from a grassland soil sample. Tetracycline antibiotics bind to the ribosomal acceptor site (A-site), preventing binding of the aminoacyl-tRNA to the A-site. The hydrophilic side of tetracycline makes many hydrogen-bonding interactions with oxygen atoms of the ribosome's phosphate backbone. Belongs to the aromatic-ring hydroxylase family.