Structural basis for efficient phosphorylation of 3'-azidothymidine monophosphate by Escherichia coli thymidylate kinase
| Autor: | Manfred Konrad, Nils Ostermann, Roger S. Goody, Ilme Schlichting, Ralf Brundiers, Jochen Reinstein, Arnon Lavie |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Models
Molecular Saccharomyces cerevisiae Molecular Sequence Data medicine.disease_cause Crystallography X-Ray Thymidylate kinase Antiviral Agents Protein Structure Secondary chemistry.chemical_compound Catalytic Domain medicine Escherichia coli Transferase Humans Enzyme kinetics Amino Acid Sequence Phosphorylation Multidisciplinary Nucleoside-phosphate kinase biology Biological Sciences biology.organism_classification Yeast Kinetics Biochemistry Deoxyribose chemistry Nucleoside-Phosphate Kinase Sequence Alignment Zidovudine Dideoxynucleotides |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 0027-8424 |
| Popis: | The crystal structures of Escherichia coli thymidylate kinase (TmpK) in complex with P 1 -(5′-adenosyl)- P 5 -(5′-thymidyl)pentaphosphate and P 1 -(5′-adenosyl)P 5 -[5′-(3′-azido-3′-deoxythymidine)] pentaphosphate have been solved to 2.0-Å and 2.2-Å resolution, respectively. The overall structure of the bacterial TmpK is very similar to that of yeast TmpK. In contrast to the human and yeast TmpKs, which phosphorylate 3′-azido-3′-deoxythymidine 5′-monophosphate (AZT-MP) at a 200-fold reduced turnover number ( k cat ) in comparison to the physiological substrate dTMP, reduction of k cat is only 2-fold for the bacterial enzyme. The different kinetic properties toward AZT-MP between the eukaryotic TmpKs and E. coli TmpK can be rationalized by the different ways in which these enzymes stabilize the presumed transition state and the different manner in which a carboxylic acid side chain in the P loop interacts with the deoxyribose of the monophosphate. Yeast TmpK interacts with the 3′-hydroxyl of dTMP through Asp-14 of the P loop in a bidentate manner: binding of AZT-MP results in a shift of the P loop to accommodate the larger substituent. In E. coli TmpK, the corresponding residue is Glu-12, and it interacts in a side-on fashion with the 3′-hydroxyl of dTMP. This different mode of interaction between the P loop carboxylic acid with the 3′ substituent of the monophosphate deoxyribose allows the accommodation of an azido group in the case of the E. coli enzyme without significant P loop movement. In addition, although the yeast enzyme uses Arg-15 (a glycine in E. coli ) to stabilize the transition state, E. coli seems to use Arg-153 from a region termed Lid instead. Thus, the binding of AZT-MP to the yeast TmpK results in the shift of a catalytic residue, which is not the case for the bacterial kinase. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|