1.7.5.1: nitrate reductase (quinone)
This is an abbreviated version!
For detailed information about nitrate reductase (quinone), go to the full flat file.
Word Map on EC 1.7.5.1
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1.7.5.1
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denitrification
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denitrify
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quinols
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dissimilatory
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chlorate
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narj
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narghji
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molybdoenzyme
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nitrate-reducing
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menaquinol
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nitrate-dependent
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q-site
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stigmatellin
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menasemiquinone
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hyscore
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menadiol
- 1.7.5.1
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denitrification
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denitrify
- quinols
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dissimilatory
- chlorate
- narj
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narghji
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molybdoenzyme
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nitrate-reducing
- menaquinol
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nitrate-dependent
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q-site
- stigmatellin
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menasemiquinone
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hyscore
- menadiol
Reaction
Synonyms
EC 1.7.99.4, gene narH, membrane-bound nitrate reductase, membrane-bound quinol:nitrate oxidoreductase, MSMEG_5140, NaR, NaR1, NarG, NarGHI, narH, NarI, NarZ, nitrate reducatse A, nitrate reductase A, nitrate reductase Z, NRA nitrate reductase A, NRZ, NRZ nitrate reductase, Pden_4236, quinol-nitrate oxidoreductase, quinol/nitrate oxidoreductase, quinol:nitrate oxidoreductase, SCO6532, SCO6533, SCO6534, SCO6535
ECTree
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General Information
General Information on EC 1.7.5.1 - nitrate reductase (quinone)
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malfunction
quinone site variants Lys86 and Gly65, Q-site inhibitor HOQNO, and their effects on heme bD, overview
metabolism
physiological function
additional information
nitrate enters the periplasm through porins where it is reduced to nitrite by the periplasmic nitrate reductase (Nap) or it is further transported into the bacterial cytosol by NarK and serves as an electron acceptor for nitrate reductase A (NarG). Periplasmic nitrite is further converted to NH3 by the periplasmic nitrite reductase (Nrf). Electrons required for these reactions can be transferred to the quinone (Q) pool by NADH:ubiquinone oxidoreductase (Nuo) in a reaction coupled to energy-conserving proton translocation
metabolism
nitrate enters the periplasm through porins where it is reduced to nitrite by the periplasmic nitrate reductase (Nap) or it is further transported into the bacterial cytosol by NarK and serves as an electron acceptor for nitrate reductase A (NarG). Periplasmic nitrite is further converted to NH3 by the periplasmic nitrite reductase (Nrf). Electrons required for these reactions can be transferred to the quinone (Q) pool by NADH:ubiquinone oxidoreductase (Nuo) in a reaction coupled to energy-conserving proton translocation
metabolism
nitrate enters the periplasm through porins where it is reduced to nitrite by the periplasmic nitrate reductase (Nap) or it is further transported into the bacterial cytosol by NarK and serves as an electron acceptor for nitrate reductase A (NarG). Periplasmic nitrite is further converted to NH3 by the periplasmic nitrite reductase (Nrf). Electrons required for these reactions can be transferred to the quinone (Q) pool by NADH:ubiquinone oxidoreductase (Nuo) in a reaction coupled to energy-conserving proton translocation
metabolism
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demethylmenasemiquinone and menasemiquinone bind in a similar and strongly asymmetric manner through a short H-bond, caused by slightly inequivalent contributions from two beta-methylene protons of the isoprenoid side chain. Their large isotropic hyperfine coupling constants are consistent with both a specific highly asymmetric binding mode of (demethyl)menasemiquinone and a near in-plane orientation of its isoprenyl chain at Cbeta relative to the aromatic ring, which differs by about 90° to that predicted for free or NarGHI-bound menaquinol
metabolism
O86717; O86716; O86714; O86715
in resting spores the Nar1 nitrate reductase requires a functional cytochrome bcc-aa3 supercomplex to reduce nitrate. Mutants lacking the complete qcr-cta genetic locus show no Nar1-dependent nitrate reduction
metabolism
NarJ serves as a chaperone for both the anaerobic respiratory nitrate reductase (NarG) and the assimilatory nitrate reductase NasC (cf. EC 1.7.1.1), the latter of which is active during both aerobic and anaerobic nitrate assimilation. Both NasC and NarG are inactive in the absence of NarJ. 50% of NarJ binds in a 1:1 complex with NasC and the remaining 50% binds in a 1:1 complex with NarG
metabolism
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in resting spores the Nar1 nitrate reductase requires a functional cytochrome bcc-aa3 supercomplex to reduce nitrate. Mutants lacking the complete qcr-cta genetic locus show no Nar1-dependent nitrate reduction
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metabolism
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NarJ serves as a chaperone for both the anaerobic respiratory nitrate reductase (NarG) and the assimilatory nitrate reductase NasC (cf. EC 1.7.1.1), the latter of which is active during both aerobic and anaerobic nitrate assimilation. Both NasC and NarG are inactive in the absence of NarJ. 50% of NarJ binds in a 1:1 complex with NasC and the remaining 50% binds in a 1:1 complex with NarG
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metabolism
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nitrate enters the periplasm through porins where it is reduced to nitrite by the periplasmic nitrate reductase (Nap) or it is further transported into the bacterial cytosol by NarK and serves as an electron acceptor for nitrate reductase A (NarG). Periplasmic nitrite is further converted to NH3 by the periplasmic nitrite reductase (Nrf). Electrons required for these reactions can be transferred to the quinone (Q) pool by NADH:ubiquinone oxidoreductase (Nuo) in a reaction coupled to energy-conserving proton translocation
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the cytochrome c containing nitrate reductase plays a role in electron transport for denitrification in Thermus thermophilus, narC mutants are defective in anaerobic growth with nitrite, NO and N2O and present decreased NADH oxidation coupled to these electron acceptors
physiological function
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mutants deficient in all three nitrate reductases narGHI, narXYZ, napFDAGHCB are capable of sustaining 48% of protoporphyrinogen IX oxidases activity and 65% of wild-type activity, respectively
physiological function
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Streptomyces coelicolor has a high capacity for nitrate reduction both during aerobic growth and when the bacterium is incubated anaerobically. During aerobic growth in liquid medium the bacterium is able to reduce 50 mM nitrate stoichiometrically to nitrite. A mutant lacking all three NarGHJI operons fails to reduce nitrate
physiological function
under nitrate-rich conditions, the nar and nap genes encoding a membrane-bound form and a periplasmic form of nitrate reductase, as well as NO-regulated genes encoding flavohaemoglobin, flavorubredoxin and hybrid cluster protein are induced following transition from the oxic to anoxic state, and 20% of nitrate consumed in steady-state is released as N2O when nitrite has accumulated to millimolar levels. In a narG mutant lacking membrane-bound nitrate reductase, the steady-state rate of N2O production was about 30-fold lower than that of the wild-type. A combination of nitrate-sufficiency, nitrite accumulation and an active Nar-type nitrate reductase leads to NO and thence N2O production, and this can account for up to 20% of the nitrate catabolized
physiological function
the NO2- that arises from human host-derived NO3- through the enzymatic activity of Mycobacterium tuberculosis enzyme NarG inhibits bacterial growth, enhances ATP synthesis, and regulates the expression of 120 genes associated with adaptation to acid, hypoxia, oxidative and nitrosative stress, and iron deprivation. Enzyme NarG can promote growth of this intracellular pathogen in NO-producing human macrophages. Importance of NO3-/NO2- reduction in the pathogenesis. Bis-molybdopterin guanine dinucleotide, the cofactor of nitrate reductase, is required for the persistence of intracellular pathogen Mycobacterium tuberculosis in guinea pigs. The enzymatic activity of Mycobacterium tuberculosis NarG inhibits bacterial growth
physiological function
NarB, NarGHJI, dehydrogenase MSMEG_2237 and MSMEG_6816 are not required for nitrate reduction as MSMEG_4206 serves as the sole assimilatory nitrate reductase
physiological function
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Streptomyces coelicolor has a high capacity for nitrate reduction both during aerobic growth and when the bacterium is incubated anaerobically. During aerobic growth in liquid medium the bacterium is able to reduce 50 mM nitrate stoichiometrically to nitrite. A mutant lacking all three NarGHJI operons fails to reduce nitrate
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physiological function
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NarB, NarGHJI, dehydrogenase MSMEG_2237 and MSMEG_6816 are not required for nitrate reduction as MSMEG_4206 serves as the sole assimilatory nitrate reductase
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physiological function
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under nitrate-rich conditions, the nar and nap genes encoding a membrane-bound form and a periplasmic form of nitrate reductase, as well as NO-regulated genes encoding flavohaemoglobin, flavorubredoxin and hybrid cluster protein are induced following transition from the oxic to anoxic state, and 20% of nitrate consumed in steady-state is released as N2O when nitrite has accumulated to millimolar levels. In a narG mutant lacking membrane-bound nitrate reductase, the steady-state rate of N2O production was about 30-fold lower than that of the wild-type. A combination of nitrate-sufficiency, nitrite accumulation and an active Nar-type nitrate reductase leads to NO and thence N2O production, and this can account for up to 20% of the nitrate catabolized
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physiological function
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the NO2- that arises from human host-derived NO3- through the enzymatic activity of Mycobacterium tuberculosis enzyme NarG inhibits bacterial growth, enhances ATP synthesis, and regulates the expression of 120 genes associated with adaptation to acid, hypoxia, oxidative and nitrosative stress, and iron deprivation. Enzyme NarG can promote growth of this intracellular pathogen in NO-producing human macrophages. Importance of NO3-/NO2- reduction in the pathogenesis. Bis-molybdopterin guanine dinucleotide, the cofactor of nitrate reductase, is required for the persistence of intracellular pathogen Mycobacterium tuberculosis in guinea pigs. The enzymatic activity of Mycobacterium tuberculosis NarG inhibits bacterial growth
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NarGHI comprises a catalytic subunit (NarG, 140 kDa), an electron-transfer subunit (NarH, 58 kDa), and a membrane anchor subunit (NarI, 26 kDa). NarG contains a Mo-bisPGD cofactor that is the site of nitrate reduction as well as a single tetranuclear iron-sulfur ([4Fe-4S]) cluster known as FS0. NarH contains three [4Fe-4S] clusters (FS1-FS3) and one trinuclear iron-sulfur cluster ([3Fe-4S], FS4). NarI anchors the NarGH subunits to the inside of the cytoplasmic membrane and contains two hemes b that are proximal (bP) and distal (bD) to the NarGH subunits, respectively
additional information
NarGHI comprises a catalytic subunit (NarG, 140 kDa), an electron-transfer subunit (NarH, 58 kDa), and a membrane anchor subunit (NarI, 26 kDa). NarG contains a Mo-bisPGD cofactor that is the site of nitrate reduction as well as a single tetranuclear iron-sulfur ([4Fe-4S]) cluster known as FS0. NarH contains three [4Fe-4S] clusters (FS1-FS3) and one trinuclear iron-sulfur cluster ([3Fe-4S], FS4). NarI anchors the NarGH subunits to the inside of the cytoplasmic membrane and contains two hemes b that are proximal (bP) and distal (bD) to the NarGH subunits, respectively
additional information
NarGHI comprises a catalytic subunit (NarG, 140 kDa), an electron-transfer subunit (NarH, 58 kDa), and a membrane anchor subunit (NarI, 26 kDa). NarG contains a Mo-bisPGD cofactor that is the site of nitrate reduction as well as a single tetranuclear iron-sulfur ([4Fe-4S]) cluster known as FS0. NarH contains three [4Fe-4S] clusters (FS1-FS3) and one trinuclear iron-sulfur cluster ([3Fe-4S], FS4). NarI anchors the NarGH subunits to the inside of the cytoplasmic membrane and contains two hemes b that are proximal (bP) and distal (bD) to the NarGH subunits, respectively
additional information
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NarGHI comprises a catalytic subunit (NarG, 140 kDa), an electron-transfer subunit (NarH, 58 kDa), and a membrane anchor subunit (NarI, 26 kDa). NarG contains a Mo-bisPGD cofactor that is the site of nitrate reduction as well as a single tetranuclear iron-sulfur ([4Fe-4S]) cluster known as FS0. NarH contains three [4Fe-4S] clusters (FS1-FS3) and one trinuclear iron-sulfur cluster ([3Fe-4S], FS4). NarI anchors the NarGH subunits to the inside of the cytoplasmic membrane and contains two hemes b that are proximal (bP) and distal (bD) to the NarGH subunits, respectively
additional information
structure-function relationships of quinone reactivity. The NarGHI catalytic activity measured with the demethylmenaquinol (DMKH2) analogue 1,4-naphthoquinol is comparable to that measured using the corresponding methylated methylmenaquinol (MKH2) analogue menadiol, kinetics, overview
additional information
structure-function relationships of quinone reactivity. The NarGHI catalytic activity measured with the demethylmenaquinol (DMKH2) analogue 1,4-naphthoquinol is comparable to that measured using the corresponding methylated methylmenaquinol (MKH2) analogue menadiol, kinetics, overview
additional information
structure-function relationships of quinone reactivity. The NarGHI catalytic activity measured with the demethylmenaquinol (DMKH2) analogue 1,4-naphthoquinol is comparable to that measured using the corresponding methylated methylmenaquinol (MKH2) analogue menadiol, kinetics, overview
additional information
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structure-function relationships of quinone reactivity. The NarGHI catalytic activity measured with the demethylmenaquinol (DMKH2) analogue 1,4-naphthoquinol is comparable to that measured using the corresponding methylated methylmenaquinol (MKH2) analogue menadiol, kinetics, overview