Crystal structure and functional characterization of yeast YLR011wp, an enzyme with NAD(P)H-FMN and ferric iron reductase activities.
Flavodoxins are involved in a variety of electron transfer reactions that are essential for life. Although FMN-binding proteins are well characterized in prokaryotic organisms, information is scarce for eukaryotic flavodoxins. We describe the 2.0-A resolution crystal structure of the Saccharomyces cerevisiae YLR011w gene product, a predicted flavoprotein. YLR011wp indeed adopts a flavodoxin fold, binds the FMN cofactor, and self-associates as a homodimer. Despite the absence of the flavodoxin key fingerprint motif involved in FMN binding, YLR011wp binds this cofactor in a manner very analogous to classical flavodoxins. YLR011wp closest structural homologue is the homodimeric Bacillus subtilis Yhda protein (25% sequence identity) whose homodimer perfectly superimposes onto the YLR011wp one. Yhda, whose function is not documented, has 53% sequence identity with the Bacillus sp. OY1-2 azoreductase. We show that YLR011wp has an NAD(P)H-dependent FMN reductase and a strong ferricyanide reductase activity. We further demonstrate a weak but specific reductive activity on azo dyes and nitrocompounds.
Liger
Dominique
D
Institut de Biochimie et de Biophysique Moléculaire et Cellulaire (CNRS-Unité Mixte de Recherche (UMR) 8619), Université Paris-Sud, Bâtiment 430, 91405 Orsay, France.
Graille
Marc
M
Zhou
Cong-Zhao
CZ
Leulliot
Nicolas
N
Quevillon-Cheruel
Sophie
S
Blondeau
Karine
K
Janin
Joël
J
van Tilbeurgh
Herman
H
D000595:Amino Acid Sequence; D001391:Azo Compounds / Q000494:pharmacology; D001407:Bacillus / Q000201:enzymology; D018360:Crystallography, X-Ray; D019281:Dimerization; D004583:Electrons; D038181:FMN Reductase / Q000737:chemistry* / Q000378:metabolism; D005292:Ferricyanides / Q000737:chemistry; D005418:Flavodoxin / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry*; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009249:NADP / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
D001391:Azo Compounds; D005292:Ferricyanides; D005418:Flavodoxin; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C007931:hexacyanoferrate III; D009249:NADP; D038181:FMN Reductase; C490376:LOT6 protein, S cerevisiae; C023903:ferric citrate iron reductase