Evolution of Function in the “Two Dinucleotide Binding Domains” Flavoproteins
Figure 7
Structural Superposition Showing the Electron Transfer Route for Members of the tDBDF Superfamily
(A) Two-electron transfer route. Residues designated with an asterisk * are from the C-terminal interacting domain of the second subunit of the acceptor proteins. Colors, PDB identifiers, and the numbers of the displayed residues are: dark red, 1grt, glutathione reductase (C42–C47, H439, E444, glutathione disulfide [only the disulfide bond is shown for ease of viewing]); plum, 1zkq, mouse thioredoxin reductase (C86–C91, H143, H497, E502, C522–C523); sea green, 1mo9, 2-ketopropyl coenzyme M oxidoreductase/carboxylase (C82–C87, F501, N503, 2-ketopropyl coenzyme M); orange, mercuric reductase (C207–C212, Y605, E610, C628, C629); chartreuse, 1yqz, CoA disulfide reductase (C43, Y419).
(B) One-electron transfer route. One-electron acceptors are forest green, 2,4-dienoylCoA reductase: 4Fe–4S cluster; goldenrod, adrenodoxin reductase: 2Fe–2S cluster; coral, dihydropyrimidine dehydrogenase: 4Fe–4S cluster; magenta, cytochrome c sulfide dehydrogenase: heme. For comparison, H439 and E444 of glutathione reductase from the two-electrons transfer group also are shown.