2fpi | pdb_00002fpi
Crystal structure of pig GTP-specific succinyl-CoA synthetase from polyethylene glycol
Structural highlights
Function[SUCA_PIG] Catalyzes the ATP- or GTP-dependent ligation of succinate and CoA to form succinyl-CoA. The nature of the beta subunit determines the nucleotide specificity (By similarity). [SUCB2_PIG] Catalyzes the GTP-dependent ligation of succinate and CoA to form succinyl-CoA (By similarity). 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 PubMedTwo isoforms of succinyl-CoA synthetase exist in mammals, one specific for ATP and the other for GTP. The GTP-specific form of pig succinyl-CoA synthetase has been crystallized in the presence of GTP and the structure determined to 2.1 A resolution. GTP is bound in the ATP-grasp domain, where interactions of the guanine base with a glutamine residue (Gln-20beta) and with backbone atoms provide the specificity. The gamma-phosphate interacts with the side chain of an arginine residue (Arg-54beta) and with backbone amide nitrogen atoms, leading to tight interactions between the gamma-phosphate and the protein. This contrasts with the structures of ATP bound to other members of the family of ATP-grasp proteins where the gamma-phosphate is exposed, free to react with the other substrate. To test if GDP would interact with GTP-specific succinyl-CoA synthetase in the same way that ADP interacts with other members of the family of ATP-grasp proteins, the structure of GDP bound to GTP-specific succinyl-CoA synthetase was also determined. A comparison of the conformations of GTP and GDP shows that the bases adopt the same position but that changes in conformation of the ribose moieties and the alpha- and beta-phosphates allow the gamma-phosphate to interact with the arginine residue and amide nitrogen atoms in GTP, while the beta-phosphate interacts with these residues in GDP. The complex of GTP with succinyl-CoA synthetase shows that the enzyme is able to protect GTP from hydrolysis when the active-site histidine residue is not in position to be phosphorylated. Interactions of GTP with the ATP-grasp domain of GTP-specific succinyl-CoA synthetase.,Fraser ME, Hayakawa K, Hume MS, Ryan DG, Brownie ER J Biol Chem. 2006 Apr 21;281(16):11058-65. Epub 2006 Feb 15. PMID:16481318[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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