Evolution of Function in the “Two Dinucleotide Binding Domains” Flavoproteins
Figure 5
The Active Sites Structure of Members of the tDBDF Superfamily
(A) The superimposed active sites of some divergent members of the tDBDF superfamily. Protein backbones are shown in gray. The cofactors and conserved sidechains important for stabilizing the isoalloxazine and nicotinamide ring complex are shown in color. The stabilizing water residues are shown as balls. Colors, PDB identifiers, and numbers of the displayed residues are as follows. DSR subgroup: dark red, glutathione reductase (1get, Glu181, Lys50); plum, mouse thioredoxin reductase (1zkq, Lys94, Glu232); and sea green, 2-ketopropyl coenzyme M oxidoreductase/carboxylase, (1mo9, Glu228, His90). NDH subgroup: magenta, flavocytochrome c sulfide dehydrogenase (1fcd, Glu167, N/A). NFR subgroup: blue, putidaredoxin reductase (1q1w, Glu163, Lys50). POR subgroup: chartreuse, NADH peroxidase (2npx, Glu163, H2O490). Group2 proteins. DCR subgroup: forest green, 2,4-dienoylCoA reductase (1ps9, Asp508, Lys421). ADR subgroup: goldenrod, adrenodoxin reductase (1e6e, Asp159, H2O16). AHR subgroup: purple, E. Coli thioredoxin reductase (1f6m, Glu167, H257). GMS subgroup: coral, dihydropyrimidine dehydrogenase (1gte, Asp346, Arg235). (Note that the structural information on the MOX subgroup was not available when this analysis was done, thus it was not represented in this figure. However, we have confirmed that it follows the same superfamily theme).
(B) Illustration showing an example of common elements of the active site.