title: Structure of adrenodoxin and function in mitochondrial steroid hydroxylation.
abstract: The three-dimensional structure of a truncated mutant of bovine adrenodoxin has been resolved at 1.85 A resolution by MAD. The protein consists of a large core region and a more flexible hairpin loop bearing residues which have been previously described as being involved in redox partner recognition. To study the role of distinct protein domains and amino acids of adrenodoxin in interaction with adrenodoxin reductase (AdR), CYP11A1 and CYP11B1, as well as in electron transfer, mutants of adrenodoxin have been prepared by site-directed mutagenesis and produced in Escherichia coli, and their structural and functional properties have been characterized in detail. It could be demonstrated that Tyr82 is located at the edge of the flexible interaction loop of adrenodoxin participating in interactions with AdR and P450s. His56, being close to Tyr82, forms a bridge between the core region of adrenodoxin and the interaction loop. Its role in transmitting changes of the cluster region to the interaction site has also been supported by functional studies. Pro108 of adrenodoxin, the only proline residue contained in the protein and being conserved in this position among several other vertebrate-type ferredoxins, has been demonstrated to be of importance for the correct folding of this protein.
authors.affiliation: Universität des Saarlandes, Biochemie, Saarbrücken, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Bernhardt
authors.forename: A
authors.initials: A
authors.lastname: Müller
authors.forename: H
authors.initials: H
authors.lastname: Uhlmann
authors.forename: A
authors.initials: A
authors.lastname: Grinberg
authors.forename: J J
authors.initials: JJ
authors.lastname: Müller
authors.forename: U
authors.initials: U
authors.lastname: Heinemann
mesh_terms: D000325:Adrenodoxin / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D002417:Cattle; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000378:metabolism; D004579:Electron Transport / Q000502:physiology; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism; D005288:Ferredoxins / Q000737:chemistry / Q000235:genetics; D006900:Hydroxylation; D008928:Mitochondria / Q000378:metabolism*; D008968:Molecular Conformation; D009154:Mutation / Q000235:genetics; D013252:Steroid 11-beta-Hydroxylase / Q000378:metabolism; D013256:Steroids / Q000378:metabolism*
chemical_list: D005288:Ferredoxins; D013256:Steroids; D000325:Adrenodoxin; C100137:putidaredoxin; D013252:Steroid 11-beta-Hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme; D005287:Ferredoxin-NADP Reductase