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Literature summary extracted from

  • Maher, M.J.; Herath, A.S.; Udagedara, S.R.; Dougan, D.A.; Truscott, K.N.
    Crystal structure of bacterial succinate quinone oxidoreductase flavoprotein SdhA in complex with its assembly factor SdhE (2018), Proc. Natl. Acad. Sci. USA, 115, 2982-2987 .
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

EC Number Cloned (Comment) Organism
1.3.5.1 gene sdhA from Escherichia coli strain MC4100, recombinant expression of non-tagged SdhA in Escherichia coli strain BL21(DE3) CodonPlus-RIL, coexpression with His6-tagged SdhE Escherichia coli

Crystallization (Commentary)

EC Number Crystallization (Comment) Organism
1.3.5.1 purified SdhA in complex with SdhE, hanging-drop vapor diffusion, mixing of 0.001 ml of 6.3 mg/ml protein in 50 mM Tris-HCl, pH 8.0, 300 mM NaCl with 0.001 ml of crystallization solution containing 0.1 M HEPES, pH 7.5, 0.2 M MgCl2 hexahydrate, 30% w/v PEG 3350, and 40 mM NaF, at 20°C, X-ray diffraction structure determination and analysis at 2.15 A resolution Escherichia coli

Localization

EC Number Localization Comment Organism GeneOntology No. Textmining
1.3.5.1 cytoplasm membrane-associated enzyme complex Escherichia coli 5737
-

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
1.3.5.1 Fe2+ within three Fe-S clusters Escherichia coli

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
1.3.5.1 succinate + a quinone Escherichia coli
-
 fumarate + a quinol
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
1.3.5.1 Escherichia coli P0AC41 subunit SdhA
-

Purification (Commentary)

EC Number Purification (Comment) Organism
1.3.5.1 recombinant non-tagged SdhA complxed with His6-tagged SdhE from Escherichia coli by nickel affinity chromatography and gel filtration to homogeneity, elution as a heterodimer with FAD covalently bound (to SdhA) within the binary complex Escherichia coli

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1.3.5.1 succinate + a quinone
-
 Escherichia coli fumarate + a quinol
-
 ?

Subunits

EC Number Subunits Comment Organism
1.3.5.1 More succinate:quinone oxidoreductase (SQR) is a multisubunit membrane-associated enzyme. The structure of SdhA is composed of four domains: an FAD-binding domain (residues 1-245 and 351-431), which includes a Rossmann-type fold and provides the binding site for FAD, a capping domain composed of residues 245-351, a helical domain composed of residues 431-547, and a C-terminal domain composed of residues 547-583. The position of the SdhA capping domain is markedly different in the SdhAE assembly relative to SQR, structure comparisons, proposed SdhA assembly pathway, detailed overview. In contrast to the significant structural rearrangements in SdhA, which accompany formation of the SdhAE complex, the structure of SdhE is virtually unchanged Escherichia coli

Synonyms

EC Number Synonyms Comment Organism
1.3.5.1 bacterial succinate:quinone oxidoreductase flavoprotein
-
 Escherichia coli
1.3.5.1 complex II
-
 Escherichia coli
1.3.5.1 SdhA
-
 Escherichia coli
1.3.5.1 SQR
-
 Escherichia coli

Cofactor

EC Number Cofactor Comment Organism Structure
1.3.5.1 FAD bound to the binding site for FAD in the FAD-binding domain (residues 1-245 and 351-431), which includes a Rossmann-type fold Escherichia coli
1.3.5.1 Fe-S cluster
-
 Escherichia coli
1.3.5.1 additional information the biogenesis of flavinylated SdhA, the catalytic subunit of SQR, is assisted by a highly conserved assembly factor termed SdhE in bacteria via an unknown mechanism. SdhE makes a direct interaction with the flavin adenine dinucleotide-linked residue His45 in SdhA and maintains the capping domain of SdhA in an open conformation. This displaces the catalytic residues of the succinate dehydrogenase active site by as much as 9.0 A compared with SdhA in the assembled SQR complex. These data suggest that bacterial SdhE proteins, and their mitochondrial homologues, are assembly chaperones that constrain the conformation of SdhA to facilitate efficient flavinylation while regulating succinate dehydrogenase activity for productive biogenesis of SQR. The SdhE protein forms an intimate complex with SdhA, with a buried surface area. Three regions of SdhE make contact with the SdhA protein, namely residues 5-25 (which encompass helix alpha1, the N terminus of alpha2, and the loop that connects these two regions), residues 47-61 (which form helix alpha4), and residues 80-86 (which form the C-terminus). Binding structure, detailed overview. rotation of the SdhA capping domain accompanies formation of the SdhAE complex. SdhE stabilizes SdhA in a nonactive conformation during assembly, mechanism of action of SdhE in the biogenesis of holo-SdhA Escherichia coli

General Information

EC Number General Information Comment Organism
1.3.5.1 metabolism succinate:quinone oxidoreductase (SQR) functions in energy metabolism, coupling the tricarboxylic acid cycle and electron transport chain in bacteria and mitochondria. The biogenesis of flavinylated SdhA, the catalytic subunit of SQR, is assisted by a highly conserved assembly factor termed SdhE in bacteria via an unknown mechanism. Bacterial SdhE proteins, and their mitochondrial homologues, seem to be assembly chaperones that constrain the conformation of SdhA to facilitate efficient flavinylation while regulating succinate dehydrogenase activity for productive biogenesis of SQR Escherichia coli
1.3.5.1 physiological function succinate:quinone oxidoreductase (SQR) is a multisubunit membrane-associated enzyme found in the cytoplasm of bacteria and in the matrix of mitochondria (where it is commonly termed complex II). The enzyme is central to cellular metabolism and energy conversion, contributing to the tricarboxylic acid cycle and the electron transport chain. It catalyzes the oxidation of succinate to fumarate, which is coupled to electron transfer through flavin adenine dinucleotide (FAD) and three Fe-S clusters, resulting in the reduction of the electron carrier ubiquinone to ubiquinol. Succinate:quinone oxidoreductase (SQR) functions in energy metabolism, coupling the tricarboxylic acid cycle and electron transport chain in bacteria and mitochondria Escherichia coli