title: Mimicking phosphorylation of Ser-74 on human deoxycytidine kinase selectively increases catalytic activity for dC and dC analogues.
abstract: Intracellular phosphorylation of dCK on Ser-74 results in increased nucleoside kinase activity. We mimicked this phosphorylation by a Ser-74-Glu mutation in bacterially produced dCK and investigated kinetic parameters using various nucleoside substrates. The S74E mutation increases the k(cat) values 11-fold for dC, and 3-fold for the anti-cancer analogues dFdC and AraC. In contrast, the rate is decreased for the purine substrates. In HEK293 cells, we found that by comparing transiently transfected dCK(S74E)-GFP and wild-type dCK-GFP, mimicking the phosphorylation of Ser-74 has no effect on cellular localisation. We note that phosphorylation may represent a mechanism to enhance the catalytic activity of the relatively slow dCK enzyme.
authors.affiliation: Max-Planck-Institute for Biophysical Chemistry, Research Group Enzyme Biochemistry, Am Fassberg 11, Göttingen, Germany.
authors.forename: Theresa
authors.initials: T
authors.lastname: McSorley
authors.forename: Stephan
authors.initials: S
authors.lastname: Ort
authors.forename: Saugata
authors.initials: S
authors.lastname: Hazra
authors.forename: Arnon
authors.initials: A
authors.lastname: Lavie
authors.forename: Manfred
authors.initials: M
authors.lastname: Konrad
mesh_terms: D021581:Active Transport, Cell Nucleus; D002384:Catalysis; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000378:metabolism*; D003842:Deoxycytidine Kinase / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D042541:Intracellular Space / Q000201:enzymology; D007700:Kinetics; D018716:Molecular Mimicry; D050505:Mutant Proteins / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D017433:Protein Structure, Secondary; D021381:Protein Transport; D013379:Substrate Specificity
chemical_list: D050505:Mutant Proteins; D003841:Deoxycytidine; D010768:Phosphoserine; D003842:Deoxycytidine Kinase