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- Knecht, W., et al.
(författare)
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Drosophila deoxyribonucleoside kinase mutants with enhanced ability to phosphorylate purine analogs
- 2007
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Ingår i: Gene Therapy. - : Springer Science and Business Media LLC. - 0969-7128 .- 1476-5462. ; 14:17, s. 1278-1286
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Tidskriftsartikel (refereegranskat)abstract
- Transduced deoxyribonucleoside kinases (dNK) can be used to kill recipient cells in combination with nucleoside prodrugs. The Drosophila melanogaster multisubstrate dNK (Dm-dNK) displays a superior turnover rate and has a great plasticity regarding its substrates. We used directed evolution to create Dm-dNK mutants with increased specificity for several nucleoside analogs (NAs) used as anticancer or antiviral drugs. Four mutants were characterized for the ability to sensitize Escherichia coli toward analogs and for their substrate specificity and kinetic parameters. The mutants had a reduced ability to phosphorylate pyrimidines, while the ability to phosphorylate purine analogs was relatively similar to the wild-type enzyme. We selected two mutants, for expression in the osteosarcoma 143B, the glioblastoma U-87M-G and the breast cancer MCF7 cell lines. The sensitivities of the transduced cell lines in the presence of the NAs fludarabine (F-AraA), cladribine (CdA), vidarabine and cytarabine were compared to the parental cell lines. The sensitivity of 143B cells was increased by 470-fold in the presence of CdA and of U-87M-G cells by 435fold in the presence of F-AraA. We also show that a choice of the selection and screening system plays a crucial role when optimizing suicide genes by directed evolution.
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- Zameitat, Elke, et al.
(författare)
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Biochemical characterization of recombinant dihydroorotate dehydrogenase from the opportunistic yeast Candida albicans
- 2006
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 273:14, s. 3183-3191
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Tidskriftsartikel (refereegranskat)abstract
- Candida albicans is the most prevalent yeast pathogen in humans, and recently it has become increasingly resistant to the current antifungal agents. In this study we investigated C. albicans dihydroorotate dehydrogenase (DHODH, EC 1.3.99.11), which catalyzes the fourth step of de novo pyrimidine synthesis, as a new target for controlling infection. We propose that the enzyme is a member of the DHODH family 2, which comprises mitochondrially bound enzymes, with quinone as the direct electron acceptor and oxygen as the final electron acceptor. Full-length DHODH and N-terminally truncated DHODH, which lacks the targeting sequence and the transmembrane domain, were subcloned from C. albicans, recombinantly expressed in Escherichia coli, purified, and characterized for their kinetics and substrate specificity. An inhibitor screening with 28 selected compounds was performed. Only the dianisidine derivative, redoxal, and the biphenyl quinoline-carboxylic acid derivative, brequinar sodium, which are known to be potent inhibitors of mammalian DHODH, markedly reduced C. albicans DHODH activity. This study provides a background for the development of antipyrimidines with high efficacy for decreasing in situ pyrimidine nucleotide pools in C. albicans.
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