Localization and nucleotide specificity ofBlastocystissuccinyl-CoA synthetase
| Autor: | Alexandra Stechmann, Daron M. Standley, Matthew B. Rogers, Karleigh Hamblin, Andrew J. Roger, Mark van der Giezen, Robin Maytum |
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| Rok vydání: | 2008 |
| Předmět: |
Models
Molecular GTP' Swine Molecular Sequence Data Protozoan Proteins Sequence alignment Blastocystis Infections Microbiology Substrate Specificity 03 medical and health sciences Succinate-CoA Ligases Organelle Animals Humans Nucleotide Binding site Purine Nucleotides Molecular Biology Research Articles Phylogeny 030304 developmental biology chemistry.chemical_classification 0303 health sciences Blastocystis Base Sequence biology Succinyl coenzyme A synthetase 030302 biochemistry & molecular biology Active site biology.organism_classification Kinetics Protein Subunits chemistry Biochemistry biology.protein Cytoplasmic Structures Sequence Alignment |
| Zdroj: | Molecular Microbiology |
| ISSN: | 1365-2958 0950-382X |
| DOI: | 10.1111/j.1365-2958.2008.06228.x |
| Popis: | The anaerobic lifestyle of the intestinal parasite Blastocystis raises questions about the biochemistry and function of its mitochondria-like organelles. We have characterized the Blastocystis succinyl-CoA synthetase (SCS), a tricarboxylic acid cycle enzyme that conserves energy by substrate-level phosphorylation. We show that SCS localizes to the enigmatic Blastocystis organelles, indicating that these organelles might play a similar role in energy metabolism as classic mitochondria. Although analysis of residues inside the nucleotide-binding site suggests that Blastocystis SCS is GTP-specific, we demonstrate that it is ATP-specific. Homology modelling, followed by flexible docking and molecular dynamics simulations, indicates that while both ATP and GTP fit into the Blastocystis SCS active site, GTP is destabilized by electrostatic dipole interactions with Lys 42 and Lys 110, the side-chains of which lie outside the nucleotide-binding cavity. It has been proposed that residues in direct contact with the substrate determine nucleotide specificity in SCS. However, our results indicate that, in Blastocystis, an electrostatic gatekeeper controls which ligands can enter the binding site. |
| Databáze: | OpenAIRE |
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