Variant of Human Enzyme Sequesters Reactive Intermediate
| Autor: | Karla L. Ewalt, Francella J. Otero, Bonnie M. Slike, Xiang-Lei Yang, Paul Schimmel, Jianming Liu |
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| Rok vydání: | 2005 |
| Předmět: |
Stereochemistry
Molecular Sequence Data Adenylate kinase Tryptophan-tRNA Ligase Aminoacylation Biology Biochemistry Pyrophosphate Catalysis chemistry.chemical_compound Protein biosynthesis Humans Point Mutation Amino Acid Sequence Peptide sequence chemistry.chemical_classification Pyrophosphatase Polymorphism Genetic Tryptophan Genetic Variation Adenosine Monophosphate Amino acid Diphosphates Enzyme Activation Kinetics Amino Acid Substitution Models Chemical chemistry Transfer RNA Mutagenesis Site-Directed |
| Zdroj: | Biochemistry. 44:4216-4221 |
| ISSN: | 1520-4995 0006-2960 |
| Popis: | In cellular environments, coupled hydrolytic reactions are used to force efficient product formation in enzyme-catalyzed reactions. In the first step of protein synthesis, aminoacyl-tRNA synthetases react with amino acid and ATP to form an enzyme-bound adenylate that, in the next step, reacts with tRNA to form aminoacyl-tRNA. The reaction liberates pyrophosphate (PP(i)) which, in turn, can be hydrolyzed by pyrophosphatase to drive efficient aminoacylation. A potential polymorphic variant of human tryptophanyl-tRNA synthetase is shown here to sequester tryptophanyl adenylate. The bound adenylate does not react efficiently with the liberated PP(i) that normally competes with tRNA to resynthesize ATP and free amino acid. Structural analysis of this variant showed that residues needed for binding ATP phosphates and thus PP(i) were reoriented from their conformations in the structure of the more common sequence variant. Significantly, the reorientation does not affect reaction with tRNA, so that efficient aminoacylation is achieved. |
| Databáze: | OpenAIRE |
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