Cloning and characterization of an Arabidopsis thaliana Nudix hydrolase homologous to the mammalian GFG protein |
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Authors: | Olejnik Kamil Kraszewska Elzbieta |
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Institution: | The Department of Plant Biochemistry, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland. |
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Abstract: | In a search for a plant antimutator MutT protein, an Arabidopsis thaliana Nudix hydrolase with homology to the mammalian GFG protein was expressed as a hexahistidine fusion polypeptide in Escherichia coli and purified to homogeneity. Unlike the GFG protein, the A. thaliana homolog could not complement the mutT mutation in a MutT-deficient E. coli strain nor was it able to hydrolyze 8-oxo-dGTP, the main substrate of the MutT protein. Instead the recombinant protein hydrolyzed a variety of nucleoside diphosphate derivatives showing a preference for ADP-ribose, with Km and k(cat) values of 1.2 mM and 2.7 s(-1) respectively. The products of ADP-ribose hydrolysis were AMP and ribose-5-phosphate. The optimal activity was at alkaline pH (8.5) with Mg2+ (5 mM) ions as the cofactor. The protein exists as a dimmer in solution. |
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