title: The copper-iron connection in biology: structure of the metallo-oxidase Fet3p.
abstract: Fet3p is a multicopper-containing glycoprotein localized to the yeast plasma membrane that catalyzes the oxidation of Fe(II) to Fe(III). This ferrous iron oxidation is coupled to the reduction of O(2) to H(2)O and is termed the ferroxidase reaction. Fet3p-produced Fe(III) is transferred to the permease Ftr1p for import into the cytosol. The posttranslational insertion of four copper ions into Fet3p is essential for its activity, thus linking copper and iron homeostasis. The mammalian ferroxidases ceruloplasmin and hephaestin are homologs of Fet3p. Loss of the Fe(II) oxidation catalyzed by these proteins results in a spectrum of pathological states, including death. Here, we present the structure of the Fet3p extracellular ferroxidase domain and compare it with that of human ceruloplasmin and other multicopper oxidases that are devoid of ferroxidase activity. The Fet3p structure delineates features that underlie the unique reactivity of this and homologous multicopper oxidases that support the essential trafficking of iron in diverse eukaryotic organisms. The findings are correlated with biochemical and physiological data to cross-validate the elements of Fet3p that define it as both a ferroxidase and cuprous oxidase.
authors.affiliation: Department of Biochemistry and the X-Ray Crystallography Core Laboratory, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Taylor
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Stoj
authors.forename: Lynn
authors.initials: L
authors.lastname: Ziegler
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Kosman
authors.forename: P John
authors.initials: PJ
authors.lastname: Hart
mesh_terms: D002570:Ceruloplasmin / Q000737:chemistry* / Q000502:physiology; D003300:Copper / Q000737:chemistry; D007501:Iron / Q000378:metabolism; D042845:Laccase / Q000737:chemistry; D017510:Protein Folding; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000502:physiology
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D003300:Copper; D007501:Iron; D042845:Laccase; D002570:Ceruloplasmin; C085513:FET3 protein, S cerevisiae