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CRYSTAL STRUCTURE OF FERRIC REDUCTASE FROM ARCHAEOGLOBUS FULGIDUSCRYSTAL STRUCTURE OF FERRIC REDUCTASE FROM ARCHAEOGLOBUS FULGIDUS
Structural highlights
FunctionFERCR_ARCFU Catalyzes the reduction of bound ferric iron (Fe(3+)) in a variety of iron chelators (siderophores) using NAD(P)H as the electron donor, resulting in the release of Fe(2+). Not active with uncomplexed Fe(3+). Also reduces FMN and FAD, but not riboflavin.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBACKGROUND: Studies performed within the last decade have indicated that microbial reduction of Fe(III) to Fe(II) is a biologically significant process. The ferric reductase (FeR) from Archaeoglobus fulgidus is the first reported archaeal ferric reductase and it catalyzes the flavin-mediated reduction of ferric iron complexes using NAD(P)H as the electron donor. Based on its catalytic activity, the A. fulgidus FeR resembles the bacterial and eukaryotic assimilatory type of ferric reductases. However, the high cellular abundance of the A. fulgidus FeR (approximately 0.75% of the total soluble protein) suggests a catabolic role for this enzyme as the terminal electron acceptor in a ferric iron-based respiratory pathway [1]. RESULTS: The crystal structure of recombinant A. fulgidus FeR containing a bound FMN has been solved at 1.5 A resolution by multiple isomorphous replacement/ anomalous diffraction (MIRAS) phasing methods, and the NADP+- bound complex of FeR was subsequently determined at 1.65 A resolution. FeR consists of a dimer of two identical subunits, although only one subunit has been observed to bind the redox cofactors. Each subunit is organized around a six-stranded antiparallel beta barrel that is homologous to the FMN binding protein from Desulfovibrio vulgaris. This fold has been shown to be related to a circularly permuted version of the flavin binding domain of the ferredoxin reductase superfamily. The A. fulgidus ferric reductase is further distinguished from the ferredoxin reductase superfamily by the absence of a Rossmann fold domain that is used to bind the NAD(P)H. Instead, FeR uses its single domain to provide both the flavin and the NAD(P)H binding sites. Potential binding sites for ferric iron complexes are identified near the cofactor binding sites. CONCLUSIONS: The work described here details the structures of the enzyme-FMN, enzyme-FMN-NADP+, and possibly the enzyme-FMN-iron intermediates that are present during the reaction mechanism. This structural information helps identify roles for specific residues during the reduction of ferric iron complexes by the A. fulgidus FeR. Crystal structures of a novel ferric reductase from the hyperthermophilic archaeon Archaeoglobus fulgidus and its complex with NADP+.,Chiu HJ, Johnson E, Schroder I, Rees DC Structure. 2001 Apr 4;9(4):311-9. PMID:11525168[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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