2scu
From Proteopedia
A detailed description of the structure of Succinyl-COA synthetase from Escherichia coli
Structural highlights
FunctionSUCD_ECOLI During aerobic metabolism it functions in the citric acid cycle, coupling the hydrolysis of succinyl-CoA to the synthesis of ATP and thus represents an important site of substrate-level phosphorylation. It can also function in the other direction for anabolic purposes, and this may be particularly important for providing succinyl-CoA during anaerobic growth when the oxidative route from 2-oxoglutarate is severely repressed. The alpha-subunit binds CoA, as well as ATP and catalyzes phosphoryl transfer to one of its histidine residues. The complete active site is probably located in the region of alpha-beta contact. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSuccinyl-CoA synthetase (SCS) carries out the substrate-level phosphorylation of GDP or ADP in the citric acid cycle. A molecular model of the enzyme from Escherichia coli, crystallized in the presence of CoA, has been refined against data collected to 2.3 A resolution. The crystals are of space group P4322, having unit cell dimensions a=b=98.68 A, c=403.76 A and the data set includes the data measured from 23 crystals. E. coli SCS is an (alphabeta)2-tetramer; there are two copies of each subunit in the asymmetric unit of the crystals. The crystal packing leaves two choices for which pair of alphabeta-dimers form the physiologically relevant tetramer. The copies of the alphabeta-dimer are similar, each having one active site where the phosphorylated histidine residue and the thiol group of CoA are found. CoA is bound in an extended conformation to the nucleotide-binding motif in the N-terminal domain of the alpha-subunit. The phosphoryl group of the phosphorylated histidine residue is positioned at the amino termini of two alpha-helices, one from the C-terminal domain of the alpha-subunit and the other from the C-terminal domain of the beta-subunit. These two domains have similar topologies, despite only 14 % sequence identity. By analogy to other nucleotide-binding proteins, the binding site for the nucleotide may reside in the N-terminal domain of the beta-subunit. If this is so, the catalytic histidine residue would have to move about 35 A to react with the nucleotide. A detailed structural description of Escherichia coli succinyl-CoA synthetase.,Fraser ME, James MN, Bridger WA, Wolodko WT J Mol Biol. 1999 Jan 29;285(4):1633-53. PMID:9917402[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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