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.
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.
Heinz
Achim
A
FR 8.3-Biochemie, Universität des Saarlandes, D-66041 Saarbrucken, Germany.
Hannemann
Frank
F
Müller
Jürgen J
JJ
Heinemann
Udo
U
Bernhardt
Rita
R
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
D000325:Adrenodoxin; D002786:Cholesterol Side-Chain Cleavage Enzyme; D005287:Ferredoxin-NADP Reductase