title: The FRE1 ferric reductase of Saccharomyces cerevisiae is a cytochrome b similar to that of NADPH oxidase.
abstract: Plasma membrane preparations from strains of the yeast Saccharomyces cerevisiae gave a reduced minus oxidized spectrum characteristic of a b-type cytochrome and very similar to the spectrum of flavocytochrome b558 of human neutrophils. The magnitude of the signal correlated with the level of ferric reductase activity and the copy number of the FRE1 gene, indicating that the FRE1 protein is a cytochrome b. Sequence similarities with the flavin binding site of flavocytochrome b558 and other members of the ferredoxin-NADP reductase family, together with increased levels of noncovalently bound FAD and iodonitrotetrazolium violet reductase activity in membranes from a yeast strain overexpressing ferric reductase, suggested that the FRE1 protein may also carry a flavin group. Potentiometric titrations indicated that FRE1, like neutrophil NADPH oxidase, has an unusually low redox potential, in the region of -250 mV, and binds CO.
authors.affiliation: Department of Medicine, University College London, 5 University Street, London WC1E 6JJ, United Kingdom.
authors.forename: K P
authors.initials: KP
authors.lastname: Shatwell
authors.forename: A
authors.initials: A
authors.lastname: Dancis
authors.forename: A R
authors.initials: AR
authors.lastname: Cross
authors.forename: R D
authors.initials: RD
authors.lastname: Klausner
authors.forename: A W
authors.initials: AW
authors.lastname: Segal
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000201:enzymology; D003573:Cytochrome b Group / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D038181:FMN Reductase; D005182:Flavin-Adenine Dinucleotide / Q000032:analysis / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D019255:NADPH Oxidases; D009504:Neutrophils / Q000201:enzymology; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D013053:Spectrophotometry; D013481:Superoxides / Q000378:metabolism
chemical_list: D003573:Cytochrome b Group; D013481:Superoxides; D005182:Flavin-Adenine Dinucleotide; C036888:cytochrome b558; D038181:FMN Reductase; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C023903:ferric citrate iron reductase