The Bacillus anthracis arylamine N-acetyltransferase ((BACAN)NAT1) that inactivates sulfamethoxazole, reveals unusual structural features compared with the other NAT isoenzymes

► We report the presence of an unexpected extra loop in the structure of Bacillus anthracis NAT1 enzyme. ► The extra loop may contribute to the shape of the active-site and to cofactor binding. ► Endogenous CoA cocrystallized with B.anthracis NAT1. ► We discuss the divergence in the mode of binding and location of CoA in NAT enzymes.