Structural Analysis of Botulinum Neurotoxin Type E Catalytic Domain and Its Mutant Glu212→Gln Reveals the Pivotal Role of the Glu212 Carboxylate in the Catalytic Pathway
| Autor: | Subramaniam Eswaramoorthy, Desigan Kumaran, Subramanyam Swaminathan, Rakhi Agarwal, Thomas Binz |
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| Rok vydání: | 2004 |
| Předmět: |
Models
Molecular Botulinum Toxins Protein Conformation Stereochemistry Structural similarity Glutamine Molecular Sequence Data Mutant Glutamic Acid Crystallography X-Ray medicine.disease_cause Biochemistry Catalysis chemistry.chemical_compound Catalytic Domain Hydrolase medicine Point Mutation Amino Acid Sequence Carboxylate Sequence Homology Amino Acid Toxin Botulinum neurotoxin type E chemistry Clostridium botulinum |
| Zdroj: | Biochemistry. 43:6637-6644 |
| ISSN: | 1520-4995 0006-2960 |
| Popis: | The seven serotypes of botulinum neurotoxins (A-G) produced by Clostridium botulinum share significant sequence homology and structural similarity. The functions of their individual domains and the modes of action are also similar. However, the substrate specificity and the peptide bond cleavage selectivity of their catalytic domains are different. The reason for this unique specificity of botulinum neurotoxins is still baffling. If an inhibitor leading to a therapeutic drug common to all serotypes is to be developed, it is essential to understand the differences in their three-dimensional structures that empower them with this unique characteristic. Accordingly, high-resolution structures of all serotypes are required, and toward achieving this goal the crystal structure of the catalytic domain of C. botulinum neurotoxin type E has been determined to 2.1 A resolution. The crystal structure of the inactive mutant Glu212--Gln of this protein has also been determined. While the overall conformation is unaltered in the active site, the position of the nucleophilic water changes in the mutant, thereby causing it to lose its ability to activate the catalytic reaction. The structure explains the importance of the nucleophilic water and the charge on Glu212. The structural differences responsible for the loss of activity of the mutant provide a common model for the catalytic pathway of Clostridium neurotoxins since Glu212 is conserved and has a similar role in all serotypes. This or a more nonconservative mutant (e.g., Glu212--Ala) could provide a novel, genetically modified protein vaccine for botulinum. |
| Databáze: | OpenAIRE |
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