tailieunhanh - Báo cáo khoa học: Structural studies of nucleoside analog and feedback inhibitor binding to Drosophila melanogaster multisubstrate deoxyribonucleoside kinase

The Drosophila melanogaster multisubstrate deoxyribonucleoside kinase (dNK; EC ) has a high turnover rate and a wide substrate range that makes it a very good candidate for gene therapy. This concept is based on introducing a suicide gene into malignant cells in order to activate a prodrug that eventually may kill the cell. | ỊFEBS Journal Structural studies of nucleoside analog and feedback inhibitor binding to Drosophila melanogaster multisubstrate deoxyribonucleoside kinase Nils E. Mikkelsen1 Birgitte Munch-Petersen2 and Hans Eklund1 1 Department of Molecular Biology Swedish University of AgriculturalSciences BiomedicalCenter Uppsala Sweden 2 Department of Science Systems and Models Roskilde University Denmark Keywords cancer gene therapy deoxyribonucleoside kinase nucleoside analogs pyrimidines X-ray structures Correspondence H. Eklund Department of Molecular Biology Swedish University of Agricultural Sciences BiomedicalCenter S-751 24 Uppsala Sweden Fax 46 18536971 Tel 46 184714559 E-mail hasse@ Received 10 January 2008 revised 27 February 2008 accepted 3 March 2008 doi The Drosophila melanogaster multisubstrate deoxyribonucleoside kinase dNK EC has a high turnover rate and a wide substrate range that makes it a very good candidate for gene therapy. This concept is based on introducing a suicide gene into malignant cells in order to activate a prodrug that eventually may kill the cell. To be able to optimize the function of dNK it is vital to have structural information of dNK complexes. In this study we present crystal structures of dNK complexed with four different nucleoside analogs floxuridine brivudine zidovudine and zalcita-bine and relate them to the binding of substrate and feedback inhibitors. dCTP and dGTP bind with the base in the substrate site similarly to the binding of the feedback inhibitor dTTP. All nucleoside analogs investigated bound in a manner similar to that of the pyrimidine substrates with many interactions in common. In contrast the base of dGTP adopted a syn-conformation to adapt to the available space of the active site. Cells need to keep a balanced pool of dNTPs to sustain DNA synthesis and repair. The main source of dNTPs comes from the de novo pathway where ribonucleosides are converted to .