UMP kinase from the Gram-positive bacterium Bacillus subtilis is strongly dependent on GTP for optimal activity
| Autor: | Antoine Danchin, Cristina Gagyi, Nadia Bucurenci, Gilles Labesse, Liliane Assairi, Augustin Ofiteru, Ovidiu Sîrbu, Octavian Bârzu, Stéphanie Landais, Anne-Marie Gilles, Mihaela Ileana Ionescu |
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| Rok vydání: | 2003 |
| Předmět: |
Models
Molecular GTP' Molecular Sequence Data Bacillus subtilis Biochemistry Bacterial Proteins Transferases heterocyclic compounds Amino Acid Sequence Cloning Molecular Genes Suppressor UMP kinase chemistry.chemical_classification biology Nucleotides Kinase Escherichia coli Proteins Carbamate kinase biology.organism_classification Molecular biology Recombinant Proteins Enzyme chemistry Specific activity Guanosine Triphosphate Nucleoside-Phosphate Kinase Sequence Alignment Nucleoside |
| Zdroj: | European Journal of Biochemistry. 270:3196-3204 |
| ISSN: | 1432-1033 0014-2956 |
| DOI: | 10.1046/j.1432-1033.2003.03702.x |
| Popis: | The gene encoding Bacillus subtilis UMP kinase (pyrH/smbA) is transcribed in vivo into a functional enzyme, which represents approximately 0.1% of total soluble proteins. The specific activity of the purified enzyme under optimal conditions is 25 units.mg-1 of protein. In the absence of GTP, the activity of B. subtilis enzyme is less than 10% of its maximum activity. Only dGTP and 3'-anthraniloyl-2'-deoxyguanosine-5'-triphosphate (Ant-dGTP) can increase catalysis significantly. Binding of Ant-dGTP to B. subtilis UMP kinase increased the quantum yield of the fluorescent analogue by a factor of more than three. UTP and GTP completely displaced Ant-dGTP, whereas GMP and UMP were ineffective. UTP inhibits UMP kinase of B. subtilis with a lower affinity than that shown towards the Escherichia coli enzyme. Among nucleoside monophosphates, 5-fluoro-UMP (5F-UMP) and 6-aza-UMP were actively phosphorylated by B. subtilis UMP kinase, explaining the cytotoxicity of the corresponding nucleosides towards this bacterium. A structural model of UMP kinase, based on the conservation of the fold of carbamate kinase and N-acetylglutamate kinase (whose crystals were recently resolved), was analysed in the light of physicochemical and kinetic differences between B. subtilis and E. coli enzymes. |
| Databáze: | OpenAIRE |
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