Fig. 4: Anhydrotetracycline binds in a substrate-like orientation in Tet(X6).

a Polder maps (Fo-Fc map contoured at 3 σ) identify the substate-like binding orientation of anhydrotetracycline (aTC) in the two chains of the Tet(X6) crystal structure. The complete Polder map is shown in Supplementary Fig. 6. Asymmetric units of anhydrotetracycline-complexed Tet(X6) X-ray crystal structure is shown in Supplementary Fig. 4. b Key interactions of anhydrotetracyclines with active site residues of Tet(X6). c Aligned crystal structures of Tet(X6)-anhydrotetracycline complex with Tet(X)-chlortetracycline (CTC) complex structure (PDB ID: 2Y6R). Aligned CTC and FAD from Tet(X) structures are shown in grey. The C11a of aTC is at 5.7Å from C4a of the FAD isoalloxazine ring.