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Literature summary extracted from

  • Hedison, T.M.; Shenoy, R.T.; Iorgu, A.I.; Heyes, D.J.; Fisher, K.; Wright, G.S.A.; Hay, S.; Eady, R.R.; Antonyuk, S.V.; Hasnain, S.S.; Scrutton, N.S.
    Unexpected roles of a tether harboring a tyrosine gatekeeper residue in modular nitrite reductase catalysis (2019), ACS Catal., 9, 6087-6099 .
    View publication on PubMedView publication on EuropePMC

Protein Variants

EC Number Protein Variants Comment Organism
1.7.2.1 Y323A about 90% of wild-type activity. Tether residue Tyr 323 is a gatekeeper for nitrite binding. The water molecules occupying free space above type 2 copper are connected by strong hydrogen bonds, while the channel space, opposite to the NiR-core, is open and contains full occupancy waters Ralstonia pickettii
1.7.2.1 Y323E about 90% of wild-type activity. Tether residue Tyr 323 is a gatekeeper for nitrite binding. The water molecules occupying free space above type 2 copper are connected by strong hydrogen bonds, while the channel space, opposite to the NiR-core, is open and contains full occupancy waters Ralstonia pickettii
1.7.2.1 Y323F about 90% of wild-type activity. Tether residue Tyr 323 is a gatekeeper for nitrite binding. Mutant has a single water, W1, bound to the type 2 copper site Ralstonia pickettii

Inhibitors

EC Number Inhibitors Comment Organism Structure
1.7.2.1 nitrite
-
 Ralstonia pickettii

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
1.7.2.1 0.0016
-
 nitrite wild-type, pH 6.5, 25°C Ralstonia pickettii
1.7.2.1 0.29
-
 nitrite core protein carrying mutation Y327F, pH 6.5, 25°C Ralstonia pickettii
1.7.2.1 0.41
-
 nitrite core protein, pH 6.5, 25°C Ralstonia pickettii

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
1.7.2.1 copper tethering does not enhance the rate of electron delivery from its pendant cytochrome c to the catalytic copper-containing core. Tethering communicates the redox state of the heme to the distant type 2 copper center that helps initiate substrate binding for catalysis. It also tunes copper reduction potentials, suppresses reductive enzyme inactivation, enhances enzyme affinity for substrate, and promotes inter-copper electron transfer Ralstonia pickettii

Organism

EC Number Organism UniProt Comment Textmining
1.7.2.1 Ralstonia pickettii B2UHR8
-
-
1.7.2.1 Ralstonia pickettii 12J B2UHR8
-
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1.7.2.1 nitrite + reduced phenazine methosulfate
-
 Ralstonia pickettii NO + oxidized phenazine methosulfate
-
 ?
1.7.2.1 nitrite + reduced phenazine methosulfate
-
 Ralstonia pickettii 12J NO + oxidized phenazine methosulfate
-
 ?

Synonyms

EC Number Synonyms Comment Organism
1.7.2.1 NiR
-
 Ralstonia pickettii
1.7.2.1 Rpic_4015
-
 Ralstonia pickettii

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
1.7.2.1 1.1
-
 nitrite wild-type, pH 6.5, 25°C Ralstonia pickettii
1.7.2.1 2.3
-
 nitrite core protein, pH 6.5, 25°C Ralstonia pickettii
1.7.2.1 2.6
-
 nitrite core protein carrying mutation Y327F, pH 6.5, 25°C Ralstonia pickettii

Ki Value [mM]

EC Number Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
1.7.2.1 130
-
 nitrite core protein, pH 6.5, 25°C Ralstonia pickettii
1.7.2.1 160
-
 nitrite core protein carrying mutation Y327F, pH 6.5, 25°C Ralstonia pickettii

General Information

EC Number General Information Comment Organism
1.7.2.1 metabolism tethering does not enhance the rate of electron delivery from its pendant cytochrome c to the catalytic copper-containing core. Tethering communicates the redox state of the heme to the distant type 2 copper center that helps initiate substrate binding for catalysis. It also tunes copper reduction potentials, suppresses reductive enzyme inactivation, enhances enzyme affinity for substrate, and promotes inter-copper electron transfer. Nitrite binding and enzyme turnover is controlled by heme reduction and prevents NiR inactivation Ralstonia pickettii

kcat/KM [mM/s]

EC Number kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
1.7.2.1 5.6
-
 nitrite core protein, pH 6.5, 25°C Ralstonia pickettii
1.7.2.1 8.8
-
 nitrite core protein carrying mutation Y327F, pH 6.5, 25°C Ralstonia pickettii
1.7.2.1 690
-
 nitrite wild-type, pH 6.5, 25°C Ralstonia pickettii