Structure-function analysis of a bacterial deoxyadenosine kinase reveals the basis for substrate specificity |
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Authors: | Welin Martin Wang Liya Eriksson Staffan Eklund Hans |
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Institution: | Department of Molecular Biology, Swedish University of Agricultural Sciences, Box 590, Biomedical Center, S-751 24 Uppsala, Sweden. |
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Abstract: | Deoxyribonucleoside kinases (dNKs) catalyze the transfer of a phosphoryl group from ATP to a deoxyribonucleoside (dN), a key step in DNA precursor synthesis. Recently structural information concerning dNKs has been obtained, but no structure of a bacterial dCK/dGK enzyme is known. Here we report the structure of such an enzyme, represented by deoxyadenosine kinase from Mycoplasma mycoides subsp. mycoides small colony type (Mm-dAK). Superposition of Mm-dAK with its human counterpart's deoxyguanosine kinase (dGK) and deoxycytidine kinase (dCK) reveals that the overall structures are very similar with a few amino acid alterations in the proximity of the active site. To investigate the substrate specificity, Mm-dAK has been crystallized in complex with dATP and dCTP, as well as the products dCMP and dCDP. Both dATP and dCTP bind to the enzyme in a feedback-inhibitory manner with the dN part in the deoxyribonucleoside binding site and the triphosphates in the P-loop. Substrate specificity studies with clinically important nucleoside analogs as well as several phosphate donors were performed. Thus, in this study we combine structural and kinetic data to gain a better understanding of the substrate specificity of the dCK/dGK family of enzymes. The structure of Mm-dAK provides a starting point for making new anti bacterial agents against pathogenic bacteria. |
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Keywords: | dNK deoxyribonucleoside kinase dN deoxyribonucleoside Mm-dAK Mycoplasma mycoides subsp mycoides small colony type deoxyadenosine kinase dGK deoxyguanosine kinase dCK deoxycytidine kinase TK thymidine kinase TK1 thymidine kinase 1 TK2 thymidine kinase 2 Dm-dNK Drosophila melanogaster deoxyribonucleoside kinase ddI 2′ 3′-dideoxyinosine ddA 2′ 3′-dideoxyadenosine ddG 2′ 3′-dideoxyguanosine ddC 2′ 3′-dideoxycytidine |
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