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Function
Nitrate reductase (NR) catalyzes the reduction of NO3 to NO2 using NADPH[1]. NR active site contains Mo atom. Four types of NR are known:
eukaryotic assimilatory NR
bacterial cytoplasmic assimilatory (NAC)
bacterial membrane-bound respiratory (NAR)
bacterial periplasmic dissimilatory (NAP).
The cofactors of NR are Molybdopterin (MPT) in eukaryotic NR and bis-Molybdopterin guanine dinucleotide (MGD) in bacterial NR.
Structural highlights
Bacterial periplasmic dissimilatory nitrate reductase containing Fe4S4 cluster with Mo, NO3 and 2 molybdepterin guanine nucleotides. NAP active site includes a six-coordinated Mo atom which coordinates to 2 MGD molecules and Cys140. The NO3 molecule is guided to the active site by a funnel leading to the Mo atom[2].
- ↑ NICHOLAS DJ, NASON A. Molybdenum and nitrate reductase. II. Molybdenum as a constituent of nitrate reductase. J Biol Chem. 1954 Mar;207(1):353-60. PMID:13152110
- ↑ Najmudin S, Gonzalez PJ, Trincao J, Coelho C, Mukhopadhyay A, Cerqueira NM, Romao CC, Moura I, Moura JJ, Brondino CD, Romao MJ. Periplasmic nitrate reductase revisited: a sulfur atom completes the sixth coordination of the catalytic molybdenum. J Biol Inorg Chem. 2008 Mar 8;. PMID:18327621 doi:10.1007/s00775-008-0359-6
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3D structures of nitrate reductase
Updated on 14-August-2018
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- Bacterial periplasmic dissimilatory NR
- 2nap, 2jim, 2jio, 2jip, 2v3v, 2v45 – DdNAP + MGD + Mo - Desulfovibrio desulfuricans
- 2jiq - DdNAP + NO3 + MGD + Mo
- 2jir - DdNAP + CN + MGD + Mo
- 1jni – NAP small subunit + heme – Haemophilus influenzae
- 1ogy - NAP + heme + MGD + Mo– Rhodobacter sphaeroides
- 2nya - EcNAP + MGD + Mo – Escherichia coli
- 3ml1, 3o5a - NAP catalytic subunit + NAPB + heme + MGD + Mo – Ralstonia eutropha
- 5yly – NR cytochrome b5 reductase domain + FAD – Ulva prolifera
- Bacterial respiratory NR
- 1q16, 1y5l – EcNAR α+β+γ chains + heme + MGD + Mo
- 1r27 - EcNAR α+β chains + MGD + Mo
- 1siw – EcNAR α+β+γ chains + heme
- 1y4z, 3egw - EcNAR α+β (mutant) + γ chains + inhibitor + heme + MGD + Mo
- 1y5i, 1y5n - EcNAR α+β + γ (mutant) chains + inhibitor + heme + MGD + Mo
- 3ir5, 3ir7 - EcNAR α (mutant) +β + γ chains + inhibitor + heme + MGD + Mo
- 3ir6 - EcNAR α (mutant) +β + γ chains + inhibitor + heme + GDP
- Eukaryotic assimilatory NR
- 2bih, 2bii – NR MoCo-binding domain + MPT – Pichia angusta
- Eukaryotic NR
- 1cne – cNR + FAD – corn
- 1cnf, 2cnd – cNR (mutant) + FAD + ADP
References
