title: Functional characterization of Fdx1: evidence for an evolutionary relationship between P450-type and ISC-type ferredoxins.
abstract: Ferredoxins are ubiquitous proteins with electron transfer activity involved in a variety of biological processes. In this work, we investigated the characteristics and function of Fdx1 from Sorangium cellulosum So ce56 by using a combination of bioinformatics and of biochemical/biophysical approaches. We were able to experimentally confirm a role of Fdx1 in the iron-sulfur cluster biosynthesis by in vitro reduction studies with cluster-loaded So ce56 IscU and by transfer studies of the cluster from the latter protein to apo-aconitase A. Moreover, we found that Fdx1 can replace mammalian adrenodoxin in supporting the activity of bovine CYP11A1. This makes S. cellulosum Fdx1 the first prokaryotic ferredoxin reported to functionally interact with this mammalian enzyme. Although the interaction with CYP11A1 is non-physiological, this is-to the best of our knowledge-the first study to experimentally prove the activity of a postulated ISC-type ferredoxin in both the ISC assembly and a cytochrome P450 system. This proves that a single ferredoxin can be structurally able to provide electrons to both cytochromes P450 and IscU and thus support different biochemical processes. Combining this finding with phylogenetic and evolutionary trace analyses led us to propose the evolution of eukaryotic mitochondrial P450-type ferredoxins and ISC-type ferredoxins from a common prokaryotic ISC-type ancestor.
authors.affiliation: Department of Biochemistry, Saarland University, D-66041 Saarbrücken, Germany.
authors.forename: Kerstin Maria
authors.initials: KM
authors.lastname: Ewen
authors.forename: Frank
authors.initials: F
authors.lastname: Hannemann
authors.forename: Stefania
authors.initials: S
authors.lastname: Iametti
authors.forename: Anna
authors.initials: A
authors.lastname: Morleo
authors.forename: Rita
authors.initials: R
authors.lastname: Bernhardt
mesh_terms: D000154:Aconitate Hydratase / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D002417:Cattle; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism; D003001:Cloning, Molecular; D019295:Computational Biology; D019143:Evolution, Molecular; D005288:Ferredoxins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D007501:Iron / Q000032:analysis; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D009231:Myxococcales / Q000235:genetics / Q000378:metabolism; D009249:NADP; D010084:Oxidation-Reduction; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D050889:Sulfite Reductase (Ferredoxin) / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005288:Ferredoxins; D007506:Iron-Sulfur Proteins; D009249:NADP; D007501:Iron; D002786:Cholesterol Side-Chain Cleavage Enzyme; D050889:Sulfite Reductase (Ferredoxin); D000154:Aconitate Hydratase