Cloned (Comment) | Organism |
---|---|
gene cluster NarGHI, overexpression in Escherichia coli strain LCB79 | Escherichia coli |
Protein Variants | Comment | Organism |
---|---|---|
G65A | site-directed mutageness of subunit NarI, mutant G65A is able to support growth and retains significant quinol:nitrate oxidoreductase activity | Escherichia coli |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
membrane | the NarI subunit anchors the NarGH subunits to the inside of the cytoplasmic membrane | Escherichia coli | 16020 | - |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
nitrite + a quinone + H2O | Escherichia coli | - |
nitrate + a quinol | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Escherichia coli | P09152 | NarG | - |
Escherichia coli | P11349 | NarH | - |
Escherichia coli | P11350 | NarI | - |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
nitrate + a quinol = nitrite + a quinone + H2O | electrons flow in the overall thermodynamically downhill direction from menaquinol (MQ) or ubiquinol (UQ) through the two hemes of NarI, the four [Fe-S] clusters of NarH, and then through the single [4Fe-4S] cluster of NarG to the Mo-bisPGD cofactor, where nitrate is reduced to nitrite | Escherichia coli |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
nitrite + a quinone + H2O | - |
Escherichia coli | nitrate + a quinol | - |
? |
Subunits | Comment | Organism |
---|---|---|
? | x * 140000, NarG subunit, SDS-PAGE | Escherichia coli |
? | x * 26000, NarI subunit, SDS-PAGE | Escherichia coli |
? | x * 58000, NarH subunit, SDS-PAGE | Escherichia coli |
Synonyms | Comment | Organism |
---|---|---|
gene narH | - |
Escherichia coli |
membrane-bound quinol:nitrate oxidoreductase | - |
Escherichia coli |
NarG | - |
Escherichia coli |
NarGHI | - |
Escherichia coli |
NarI | - |
Escherichia coli |
nitrate reductase A | - |
Escherichia coli |
quinol:nitrate oxidoreductase | - |
Escherichia coli |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | - |
assay at | Escherichia coli |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7 | - |
assay at | Escherichia coli |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
heme | the membrane subunit (NarI) of Escherichia coli nitrate reductase A (NarGHI) contains two b-type hemes, both of which are the highly anisotropic low-spin type. Heme bD is distal to NarGH and constitutes part of the quinone binding and oxidation site (Q-site) through the axially coordinating His66 residue and one of the heme bD propionate groups. Bound quinone participates in hydrogen bonds with both the imidazole of His66 and the heme propionate | Escherichia coli | |
molybdo-bis(pyranopterin guanine dinucleotide) | Mo-bisPGD cofactor, bound to subunit NarG. 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 | Escherichia coli | |
quinone | heme bD is distal to NarGH and constitutes part of the quinone binding and oxidation site (Q-site) through the axially coordinating His66 residue and one of the heme bD propionate groups. Bound quinone participates in hydrogen bonds with both the imidazole of His66 and the heme propionate | Escherichia coli | |
[4Fe-4S]-center | a single tetranuclear iron-sulfur [4Fe-4S] cluster, known as FS0, is bound to subunit NarG. NarH contains three [4Fe-4S] clusters (FS1-FS3) and one trinuclear iron-sulfur cluster ([3Fe-4S], FS4) | Escherichia coli |
General Information | Comment | Organism |
---|---|---|
malfunction | quinone site variants Lys86 and Gly65, Q-site inhibitor HOQNO, and their effects on heme bD, overview | Escherichia coli |
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 | Escherichia coli |