Fig. 3. FAD- and ubiquinone-binding pockets in the structures of cFSP1^ΔN in complex with CoQ₁.

a FAD-binding pocket, the FAD and FAD-contacting residues are labeled and shown as stick representations, and the nitrogen and oxygen atoms are coloured in blue and red, respectively. The carbon atoms of the FAD and FAD-contacting residues are coloured in pink and yellow, respectively, the hydrogen bonds are shown in black dashed lines. b Interactions between the isoalloxazine ring of the FAD and the cFSP1 protein, residues Val49, Glu155, Lys354, Tyr295, and Tyr343 from the other monomer of the dimer are labeled and shown as stick representations. c Ubiquinone-binding pocket, the CoQ₁ and the residues lining the pocket are labeled and shown as stick representations. The 2Fo − Fc electron density (black) is contoured at 1.0 σ and shown for FAD and CoQ₁. d Clipped surface representation of the FSP1 dimer showing the pockets in one monomer. The clipped interior surfaces of the two monomers were coloured as wheat and light blue, respectively. The FAD-binding and CoQ-binding pockets were occupied by FAD (pink carbon atoms) and CoQ₁ (cyan carbon atoms), respectively. The NAD(P)(H)-binding and FAD hydroxylation pockets were indicated by blue and red dashed lines, respectively.