1i0s
From Proteopedia
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ARCHAEOGLOBUS FULGIDUS FERRIC REDUCTASE COMPLEX WITH NADP+
Overview
BACKGROUND: 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.
About this Structure
1I0S is a Single protein structure of sequence from Archaeoglobus fulgidus with FMN and NAP as ligands. Full crystallographic information is available from OCA.
Reference
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
Page seeded by OCA on Sun Nov 25 03:25:18 2007
