Uhlin, Ulla
- Department of Molecular Biology, Swedish University of Agricultural Sciences
Abstract
The first step for the intracellular retention of several anticancer or antiviral nucleoside analogues is the addition of a phosphate group catalysed by a deoxyribonucleoside kinase such as thymidine kinase 1 (TK1). Recently, human TK1 (HuTK1) has been crystallized and characterized using different ligands. To improve our understanding of TK1 substrate specificity, we performed a detailed, mutation-based comparative structurefunction study of the active sites of two thymidine kinases: HuTK1 and Caenorhabditis elegans TK1 (CeTK1). Specifically, mutations were introduced into the hydrophobic pocket surrounding the substrate base. In CeTK1, some of these mutations led to increased activity with deoxycytidine and deoxyguanosine, two unusual substrates for TK1-like kinases. In HuTK1, mutation of T163 to S resulted in a kinase with a 140-fold lower Km for the antiviral nucleoside analogue 3-azido-3'-deoxythymidine (AZT) compared with the natural substrate thymidine. The crystal structure of the T163S-mutated HuTK1 reveals a less ordered conformation of the ligand thymidine triphosphate compared with the wild-type structure but the cause of the changed specificity towards AZT is not obvious. Based on its highly increased AZT activity relative to thymidine activity this TK1 mutant could be suitable for suicide gene therapy.
Keywords
crystal structure; enzyme kinetics; mutagenesis; nucleoside analogue; thymidine kinase 1
Published in
FEBS Journal
2012, volume: 279, number: 10, pages: 1777-1787
Publisher: WILEY-BLACKWELL
SLU Authors
Global goals (SDG)
SDG3 Good health and well-being
UKÄ Subject classification
Biochemistry
Molecular Biology
Publication identifier
- DOI: https://doi.org/10.1111/j.1742-4658.2012.08554.x
Permanent link to this page (URI)
https://res.slu.se/id/publ/45615