Fig. 1
Crystal structure of Osm1 in a complex with the FAD cofactor and substrate. a Schematic of the enzymatic reaction catalyzed by fumarate reductase. b Domain structure of Osm1 and a representative soluble fumarate reductase, Fcc3, from Shewanella frigidimarina. The individual domains are indicated by different colors, as shown. The Osm1 construct containing residues 32–501 used in the current structural study is indicated by the black triangles. The two different translational start sites, M1 and M33, are indicated by the arrows. ER endoplasmic reticulum, Mt mitochondria. c Ribbon diagram of the structure of Osm1 in a complex with FAD and substrate. Two distinct domains are shown with light blue for the flavin domain and light pink for the clamp domain. Bound FAD and substrate are shown in green and red, respectively. d Multi-angle light scattering (MALS) measurement of Osm1 in a complex with FAD and substrate. The x-axis and y-axis indicate the elution volume and molecular mass, respectively. e Comparison of the active site and the FAD-binding site of Osm1 with other Fcc3 structures. The color codes are indicated. f Comparison of the Osm1 structure with a representative structural homolog by superposition of Osm1 with Fcc3 from S. frigidimarina. The clamp domain and the flavin domain are indicated in light blue and pink, respectively. The heme domain found only in the Fcc3 family is indicated in green. g Electrostatic surface representation of both Osm1 and Fcc3 from S. frigidimarina. The domain boundaries are indicated by black lines
