Fig. 2: Heme-binding and FAD-binding sites and interactions between the TM and DH domains.
From: Structural and mechanistic insights into Streptococcus pneumoniae NADPH oxidase
a, Cartoon representation of the structure of NADPH-bound SpNOX. Areas of interest are highlighted with colored dashed boxes. b, The two B-type hemes are coordinated by two histidine pairs H83 + H142 (outer heme) and H69 + H129 (inner heme) of the transmembrane helices TM3 and TM5. The edge-to-edge distance is indicated with a dashed line. TM1 and TM2 are omitted for clarity. c, Detailed view of the FAD-binding site. Side chains and FAD are shown as sticks. d, Closer look into the interface interactions between the TM and the DH domains. In c,d, water molecules are shown as red spheres and atoms within H-bond distance are marked with cyan dashed lines. e, The C-terminal tail of SpNOX lies at the interface of the TM and DH domains, is oriented orthogonal to the membrane plane and interacts by H-bonds between K70 at TM3 and F399.
