2nap

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DISSIMILATORY NITRATE REDUCTASE (NAP) FROM DESULFOVIBRIO DESULFURICANS

Overview

BACKGROUND: The periplasmic nitrate reductase (NAP) from the sulphate, reducing bacterium Desulfovibrio desulfuricans ATCC 27774 is induced by, growth on nitrate and catalyses the reduction of nitrate to nitrite for, respiration. NAP is a molybdenum-containing enzyme with one, bis-molybdopterin guanine dinucleotide (MGD) cofactor and one [4Fe-4S], cluster in a single polypeptide chain of 723 amino acid residues. To date, there is no crystal structure of a nitrate reductase. RESULTS: The first, crystal structure of a dissimilatory (respiratory) nitrate reductase was, determined at 1.9 A resolution by multiwavelength anomalous diffraction, (MAD) methods. The structure is folded into four domains with an, alpha/beta-type topology and all four domains are involved in cofactor, binding. The [4Fe-4S] centre is located near the periphery of the, molecule, whereas the MGD cofactor extends across the interior of the, molecule interacting with residues from all four domains. The molybdenum, atom is located at the bottom of a 15 A deep crevice, and is positioned 12, A from the [4Fe-4S] cluster. The structure of NAP reveals the details of, the catalytic molybdenum site, which is coordinated to two MGD cofactors, Cys140, and a water/hydroxo ligand. A facile electron-transfer pathway, through bonds connects the molybdenum and the [4Fe-4S] cluster., CONCLUSIONS: The polypeptide fold of NAP and the arrangement of the, cofactors is related to that of Escherichia coli formate dehydrogenase, (FDH) and distantly resembles dimethylsulphoxide reductase. The close, structural homology of NAP and FDH shows how small changes in the vicinity, of the molybdenum catalytic site are sufficient for the substrate, specificity.

About this Structure

2NAP is a Single protein structure of sequence from Desulfovibrio desulfuricans with , , and as ligands. Known structural/functional Sites: and . Full crystallographic information is available from OCA.

Reference

Crystal structure of the first dissimilatory nitrate reductase at 1.9 A solved by MAD methods., Dias JM, Than ME, Humm A, Huber R, Bourenkov GP, Bartunik HD, Bursakov S, Calvete J, Caldeira J, Carneiro C, Moura JJ, Moura I, Romao MJ, Structure. 1999 Jan 15;7(1):65-79. PMID:10368307[[Category: [4fe-4s] cluster]]

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