title: The interaction domain of the redox protein adrenodoxin is mandatory for binding of the electron acceptor CYP11A1, but is not required for binding of the electron donor adrenodoxin reductase.
abstract: Adrenodoxin (Adx) is a [2Fe-2S] ferredoxin involved in electron transfer reactions in the steroid hormone biosynthesis of mammals. In this study, we deleted the sequence coding for the complete interaction domain in the Adx cDNA. The expressed recombinant protein consists of the amino acids 1-60, followed by the residues 89-128, and represents only the core domain of Adx (Adx-cd) but still incorporates the [2Fe-2S] cluster. Adx-cd accepts electrons from its natural redox partner, adrenodoxin reductase (AdR), and forms an individual complex with this NADPH-dependent flavoprotein. In contrast, formation of a complex with the natural electron acceptor, CYP11A1, as well as electron transfer to this steroid hydroxylase is prevented. By an electrostatic and van der Waals energy minimization procedure, complexes between AdR and Adx-cd have been proposed which have binding areas different from the native complex. Electron transport remains possible, despite longer electron transfer pathways.
authors.affiliation: FR 8.3-Biochemie, Universität des Saarlandes, D-66041 Saarbrucken, Germany.
authors.forename: Achim
authors.initials: A
authors.lastname: Heinz
authors.forename: Frank
authors.initials: F
authors.lastname: Hannemann
authors.forename: Jürgen J
authors.initials: JJ
authors.lastname: Müller
authors.forename: Udo
authors.initials: U
authors.lastname: Heinemann
authors.forename: Rita
authors.initials: R
authors.lastname: Bernhardt
mesh_terms: D000325:Adrenodoxin / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000737:chemistry* / Q000378:metabolism*; D002942:Circular Dichroism; D005287:Ferredoxin-NADP Reductase / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D013816:Thermodynamics
chemical_list: D000325:Adrenodoxin; D002786:Cholesterol Side-Chain Cleavage Enzyme; D005287:Ferredoxin-NADP Reductase