title: FAD oxidizes the ERO1-PDI electron transfer chain: the role of membrane integrity.
abstract: The molecular steps of the electron transfer in the endoplasmic reticulum from the secreted proteins during their oxidation are relatively unknown. We present here that flavine adenine dinucleotide (FAD) is a powerful oxidizer of the oxidoreductase system, Ero1 and PDI, besides the proteins of rat liver microsomes and HepG2 hepatoma cells. Inhibition of FAD transport hindered the action of FAD. Microsomal membrane integrity was mandatory for all FAD-related oxidation steps downstream of Ero1. The PDI inhibitor bacitracin could inhibit FAD-mediated oxidation of microsomal proteins and PDI, but did not hinder the FAD-driven oxidation of Ero1. Our data demonstrated that Ero1 can utilize FAD as an electron acceptor and that FAD-driven protein oxidation goes through the Ero1-PDI pathway and requires the integrity of the endoplasmic reticulum membrane. Our findings prompt further studies to elucidate the membrane-dependent steps of PDI oxidation and the role of FAD in redox folding.
authors.affiliation: Department of Medical Chemistry, Semmelweis University, H-1088 Budapest, Hungary.
authors.forename: Eszter
authors.initials: E
authors.lastname: Papp
authors.forename: Gábor
authors.initials: G
authors.lastname: Nardai
authors.forename: József
authors.initials: J
authors.lastname: Mandl
authors.forename: Gábor
authors.initials: G
authors.lastname: Bánhegyi
authors.forename: Péter
authors.initials: P
authors.lastname: Csermely
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D005182:Flavin-Adenine Dinucleotide / Q000008:administration & dosage*; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D045222:Electron Transport Chain Complex Proteins; D006023:Glycoproteins; D029701:Saccharomyces cerevisiae Proteins; D005182:Flavin-Adenine Dinucleotide; D050862:Oxidoreductases Acting on Sulfur Group Donors; C113186:ERO1 protein, S cerevisiae; D019704:Protein Disulfide-Isomerases