Disease relevance of dnk

• Dm-dNK is closely related to human and herpes simplex virus deoxyribonucleoside kinases [1].
• We have in the present study cloned the Dm-dNK cDNA, expressed the 29-kDa protein in Escherichia coli, and characterized the recombinant enzyme for the phosphorylation of nucleosides and clinically important nucleoside analogs [1].
• Gemcitabine resistance due to deoxycytidine kinase deficiency can be reverted by fruitfly deoxynucleoside kinase, DmdNK, in human uterine sarcoma cells [2].

High impact information on dnk

• The mutations converted the dNK substrate specificity from predominantly pyrimidine specific into purine specific [3].
• When the structures of the human deoxyguanosine kinase (dGK, EC 2.7.1.113) and the dNK from Drosophila melanogaster were compared, a limited number of amino acid residues were identified and proposed to be responsible for the substrate specificity [3].
• Insects appear to have only one multisubstrate deoxyribonucleoside kinase (dNK, EC 2.7.1.145), which prefers pyrimidine nucleosides, but can also phosphorylate purine substrates [3].
• A few amino acid substitutions can convert deoxyribonucleoside kinase specificity from pyrimidines to purines [3].
• The DNA is degraded to nucleosides, 5-methylcytosine purified by HPLC and, for detection by 1D- and 2D-TLC, radiolabeled using deoxynucleoside kinase and [gamma-(32)P]ATP [4].

Chemical compound and disease context of dnk

• Novel N1-substituted thymine derivatives related to 1-[(Z)-4-(triphenylmethoxy)-2-butenyl]thymine have been synthesized and evaluated against thymidine kinase-2 (TK-2) and related nucleoside kinases [i.e., Drosophila melanogaster deoxynucleoside kinase (Dm-dNK) and herpes simplex virus type 1 thymidine kinase (HSV-1 TK)] [5].

Biological context of dnk

• Active site mutants of Drosophila melanogaster multisubstrate deoxyribonucleoside kinase [6].
• These findings indicate that BVDU phosphorylated by Dm-dNK in transduced cancer cells may also induce bystander cell death in certain cell lines [7].
• We have evaluated the substrate specificity and kinetic properties of Dm-dNK proteins containing M88R, V84A+M88R or V84A+M88R+A110D mutations in the amino-acid sequence [8].
• Bystander effects of cancer cell lines transduced with the multisubstrate deoxyribonucleoside kinase of Drosophila melanogaster and synergistic enhancement by hydroxyurea [7].
• The transfection of Messa 10 K cells with DmdNK significantly increased the sensitivity to gemcitabine [2].

Anatomical context of dnk

• We have recently shown that the overexpression of Drosophila melanogaster multisubstrate deoxyribonucleoside kinase (Dm-dNK) in cancer cell lines increases the cells' sensitivity to several cytotoxic nucleoside analogs and the enzyme may accordingly be used as a suicide gene in combined gene/chemotherapy treatment of cancer [9].
• In summary, we showed that the cells' sensitivity and the efficiency of bystander cell killing were not dependent on whether Dm-dNK was located in the nucleus or cytosol [9].
• We showed that Dm-dNK can be expressed in human cells, that the enzyme retained its enzymatic activity, and that it is localized in the cell nuclei due to a nuclear localization signal in its C-terminal region [10].
• The Drosophila melanogaster deoxynucleoside kinase gene was introduced into HeLa cells with cationic lipids to allow its transient expression, and cytotoxic effects of several nucleoside analogs in the transfected cells were examined [11].

Associations of dnk with chemical compounds

• Drosophila melanogaster cells express a multi-substrate deoxyribonucleoside kinase that phosphorylates both purine and pyrimidine deoxyribonucleosides [12].
• The antiherpetic agent (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) was found to be an efficient substrate for recombinant Drosophila melanogaster-deoxyribonucleoside kinase with a K(m) of 4.5 microM and a V(max) of 400 nmol/microg protein/h compared with 1.3 microM and 62.5 nmol/microg protein/h, respectively, for the natural substrate thymidine [13].
• The insect multisubstrate deoxyribonucleoside kinases Bm-dNK and Dm-dNK were only inhibited by thymidine triphosphate, while Xen-PyK was inhibited by thymidine and deoxycytidine triphosphate in a complex pattern depending on the deoxyribonucleoside substrate [14].
• This provides a binding space for more bulky 3'-substituents like the azido group in AZT but influences negatively the interactions between Dm-dNK, substrates and feedback inhibitors based on deoxyribose [15].
• Here we report the structure of the Drosophila deoxyribonucleoside kinase with deoxycytidine bound at the nucleoside binding site and that of the human deoxyguanosine kinase with ATP at the nucleoside substrate binding site [16].

Analytical, diagnostic and therapeutic context of dnk

• The cDNA cloning and characterization of Dm-dNK will be the basis for studies on the use of this multisubstrate nucleoside kinase as a suicide gene in combined gene/chemotherapy of cancer [1].
• The detailed picture of the structure-function relationship provides an improved background for future development of novel mutant suicide genes for Dm-dNK-mediated gene therapy [15].

References