Interactions of GTP with the ATP-grasp domain of GTP-specific succinyl-CoA synthetase
| Autor: | Edward R. Brownie, Koto Hayakawa, David G. Ryan, Marie E. Fraser, Millicent S. Hume |
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| Rok vydání: | 2006 |
| Předmět: |
Models
Molecular Guanine GTP' Arginine Nitrogen Protein Conformation Swine Glutamine Ribose Plasma protein binding Crystallography X-Ray Biochemistry Phosphates Residue (chemistry) chemistry.chemical_compound Protein structure Adenosine Triphosphate Succinate-CoA Ligases Animals Protein Isoforms Histidine Binding site Phosphorylation Promoter Regions Genetic Molecular Biology Binding Sites Succinyl coenzyme A synthetase Hydrolysis Cell Biology chemistry Guanosine Triphosphate Protein Binding |
| Zdroj: | The Journal of biological chemistry. 281(16) |
| ISSN: | 0021-9258 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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