Literature summary for 1.3.5.1 extracted from

Guan, H.H.; Hsieh, Y.C.; Lin, P.J.; Huang, Y.C.; Yoshimura, M.; Chen, L.Y.; Chen, S.K.; Chuankhayan, P.; Lin, C.C.; Chen, N.C.; Nakagawa, A.; Chan, S.I.; Chen, C.J.
Structural insights into the electron/proton transfer pathways in the quinol fumarate reductase from Desulfovibrio gigas (2018), Sci. Rep., 8, 14935 .

Crystallization (Commentary)

Crystallization (Comment)	Organism
purified native enzyme, hanging drop vapour diffusion method, mixing of 0.001 ml of protein solution and 0.001 ml of reservoir solution, and equilibration against 0.15 ml of reservoir solution containing 100 mM NaCl, 28% PEG 4000, and 100 mM Tris, pH 8.5, at 18 °C for two weeks, X-ray diffraction structure determination and analysis at resolution 3.6 A, molecular replacement method using the structure of QFR from Wolinella succinogenes (PDB ID 2BS2) without redox cofactors as the search model, modelling	Megalodesulfovibrio gigas

Crystallization (Comment)

Organism

purified native enzyme, hanging drop vapour diffusion method, mixing of 0.001 ml of protein solution and 0.001 ml of reservoir solution, and equilibration against 0.15 ml of reservoir solution containing 100 mM NaCl, 28% PEG 4000, and 100 mM Tris, pH 8.5, at 18 °C for two weeks, X-ray diffraction structure determination and analysis at resolution 3.6 A, molecular replacement method using the structure of QFR from Wolinella succinogenes (PDB ID 2BS2) without redox cofactors as the search model, modelling

Megalodesulfovibrio gigas

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
membrane	quinol:fumarate reductase (QFR) is an integral membrane protein	Megalodesulfovibrio gigas	16020	-

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
succinate + menaquinone	Megalodesulfovibrio gigas	-	fumarate + menaquinol	-	?
succinate + menaquinone	Megalodesulfovibrio gigas DSM 1382	-	fumarate + menaquinol	-	?

Organism

Organism	UniProt	Comment	Textmining
Megalodesulfovibrio gigas	T2G9X8	-	-
Megalodesulfovibrio gigas DSM 1382	T2G9X8	-	-

Purification (Commentary)

Purification (Comment)	Organism
native enzyme from cell-free supernatant of cell extract by anion exchange chromatography, dialysis, and another anion exchange chromatography, followed gel filtration and ultrafiltration	Megalodesulfovibrio gigas

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.
additional information	analysis of the electron/proton transfer pathways in the quinol:fumarate reductase from Desulfovibrio gigas, overview	Megalodesulfovibrio gigas	?	-	-
additional information	analysis of the electron/proton transfer pathways in the quinol:fumarate reductase from Desulfovibrio gigas, overview	Megalodesulfovibrio gigas DSM 1382	?	-	-
succinate + menaquinone	-	Megalodesulfovibrio gigas	fumarate + menaquinol	-	?
succinate + menaquinone	-	Megalodesulfovibrio gigas DSM 1382	fumarate + menaquinol	-	?

Subunits

Subunits	Comment	Organism
homodimer	QFR is a homodimer, each protomer comprising two hydrophilic subunits, A and B, and one transmembrane subunit C, together with six redox cofactors including two b-hemes. One menaquinone molecule is bound near heme bL in the hydrophobic subunit C. Two heterotrimeric complexes, each comprising subunits A, B and C, form one stable homodimer (A2B2C2) with major contacts between two C subunit. The formation of the homo-dimer, (A2B2C2), arises from contact of the two C subunits	Megalodesulfovibrio gigas

Synonyms

Synonyms	Comment	Organism
fdrB	-	Megalodesulfovibrio gigas
QFR	-	Megalodesulfovibrio gigas
quinol:fumarate reductase	-	Megalodesulfovibrio gigas

Temperature Optimum [°C]

Temperature Optimum [°C]	Temperature Optimum Maximum [°C]	Comment	Organism
37	-	assay at	Megalodesulfovibrio gigas

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
7.6	-	assay at	Megalodesulfovibrio gigas

Cofactor

Cofactor	Comment	Organism	Structure
heme b	two b-hemes are bound per homodimer	Megalodesulfovibrio gigas
menaquinone	one menaquinone molecule is bound near heme bL in the hydrophobic subunit C	Megalodesulfovibrio gigas

General Information

General Information	Comment	Organism
evolution	one menaquinone molecule is bound near heme bL in the hydrophobic subunit C. This location of the menaquinone-binding site differs from the menaquinol-binding cavity proposed previously for QFR from Wolinella succinogenes. The observed bound menaquinone might serve as an additional redox cofactor to mediate the proton-coupled electron transport across the membrane	Megalodesulfovibrio gigas
metabolism	QFR catalyzes the coupled reduction of fumarate to succinate with the oxidation of hydroquinone (quinol) to quinone on opposite sides of the inner cytoplasmic membrane. The reverse reaction, namely, the coupled oxidation of succinate to fumarate with the reduction of quinone to quinol, is catalyzed by the well-studied succinate:quinone reductase (SQR, EC 1.3.5.1), often referred to as complex II in the respiratory electron-transport chain of aerobic organisms	Megalodesulfovibrio gigas
additional information	quinol:fumarate reductase (QFR) is an integral membrane protein with three subunits: a flavoprotein (subunit A), an iron-sulphur protein (subunit B), and a membrane-embedded subunit (subunit C)	Megalodesulfovibrio gigas
physiological function	the membrane-embedded quinol:fumarate reductase (QFR) in anaerobic bacteria catalyzes the reduction of fumarate to succinate by quinol in the anaerobic respiratory chain	Megalodesulfovibrio gigas