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| [[Image:2fpg.gif|left|200px]] | | {{Seed}} |
| | [[Image:2fpg.png|left|200px]] |
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| {{STRUCTURE_2fpg| PDB=2fpg | SCENE= }} | | {{STRUCTURE_2fpg| PDB=2fpg | SCENE= }} |
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| '''Crystal structure of pig GTP-specific succinyl-CoA synthetase in complex with GDP'''
| | ===Crystal structure of pig GTP-specific succinyl-CoA synthetase in complex with GDP=== |
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| ==Overview==
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| Two 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_16481318}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16481318 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16481318}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Fraser, M E.]] | | [[Category: Fraser, M E.]] |
| [[Category: Active site histidine residue]] | | [[Category: Active site histidine residue]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 04:10:01 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 17:46:39 2008'' |
