title: Sulfolobus tokodaii ST2133 is characterized as a thioredoxin reductase-like ferredoxin:NADP+ oxidoreductase.
abstract: The putative gene (st2133) for ferredoxin:NADP(+) oxidoreductase (FNR) from Sulfolobus tokodaii, a thermoacidophilic crenarchaeon, was heterologously expressed. About 90% of the purified product was a homodimer containing 0.46 mol FAD/mol subunit, and showing NADPH:DCPIP oxidoreductase activity, V max being 1.38 and 21.8 U/mg (70 °C) in the absence and presence of 1 mM FMN. NADPH was a much better electron donor than NADH with various electron acceptors, such as oxygen, hydrogen peroxide, DCPIP, cytochrome c, and dithiobisnitrobenzoate. Most of the reactions were activated by 15- to 140-fold on addition of FMN, while FAD was 5-10 times less effective. Ferredoxin (Fd) from S. tokodaii served as an electron carrier in both Fd-dependent NADPH formation and NADPH-dependent Fd reduction. ST2133 belongs to the thioredoxin reductase-like protein family, which is slightly distantly related to FNR family proteins from bacteria, plants and man. This is the first report on FNR from a crenarchaeon, providing a clue to the recycling of Fd during archaeal metabolism.
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yan
authors.forename: Young-Woo
authors.initials: YW
authors.lastname: Nam
authors.forename: Shinya
authors.initials: S
authors.lastname: Fushinobu
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Wakagi
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D005287:Ferredoxin-NADP Reductase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D016944:Sulfolobus / Q000201:enzymology*
chemical_list: D019843:Archaeal Proteins; D005287:Ferredoxin-NADP Reductase