Characterization of a membrane-bound NADH-dependent Fe(3+) reductase from the dissimilatory Fe(3+)-reducing bacterium Geobacter sulfurreducens.
Geobacter sulfurreducens produces a single, membrane-associated Fe(3+) reductase activity when grown on fumarate or Fe(3+). The activity was initially isolated by solubilization of membranes with the non-ionic detergent dodecyl-beta-D-maltoside, and partially purified by a combination of ion exchange chromatography and preparative non-denaturing gel electrophoresis. Molecular mass of the reductase, as determined by gel filtration chromatography, was approximately 300 kDa. Cofactor analysis of the purified reductase demonstrates that it contains a hemoprotein and flavin adenine dinucleotide. Kinetic and inhibitor studies show that the reductase is specific for NADH as electron donor, and confirm that the reductase enzymatically reduces Fe(3+). The cytochrome associated with the complex undergoes a reoxidation upon addition of Fe(3+) compounds, indicating an ability to pass reducing equivalents to Fe(3+). This is the first description of a purified NADH-dependent Fe(3+) reductase from a microorganism capable of coupling Fe(3+) reduction to growth.
Magnuson
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Department of Microbiology, Morrill Science Center, University of Massachusetts, Amherst, MA, USA.
Hodges-Myerson
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Lovley
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DR
D002462:Cell Membrane / Q000201:enzymology*; D020564:Deltaproteobacteria / Q000201:enzymology* / Q000254:growth & development; D038181:FMN Reductase; D005290:Ferric Compounds / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000302:isolation & purification* / Q000378:metabolism*; D010084:Oxidation-Reduction
D005290:Ferric Compounds; D038181:FMN Reductase; D009247:NADH, NADPH Oxidoreductases; C023903:ferric citrate iron reductase