Cloning and characterization of an adenosine kinase from Physcomitrella involved in cytokinin metabolism

Authors

  • Klaus Vo,

    1. , Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique Centre Versailles, F-78026 Versailles Cedex, France,, Institut Biologie II, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany, and, Biology Department, University of Waterloo, ON, Canada N2L 3G1
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  • Schwartzenberg,

    1. , Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique Centre Versailles, F-78026 Versailles Cedex, France,, Institut Biologie II, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany, and, Biology Department, University of Waterloo, ON, Canada N2L 3G1
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  • Sven Kruse,

    1. , Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique Centre Versailles, F-78026 Versailles Cedex, France,, Institut Biologie II, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany, and, Biology Department, University of Waterloo, ON, Canada N2L 3G1
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  • Ralf Reski,

    1. , Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique Centre Versailles, F-78026 Versailles Cedex, France,, Institut Biologie II, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany, and, Biology Department, University of Waterloo, ON, Canada N2L 3G1
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  • Barbara Moffatt,

    1. , Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique Centre Versailles, F-78026 Versailles Cedex, France,, Institut Biologie II, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany, and, Biology Department, University of Waterloo, ON, Canada N2L 3G1
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  • Michel Laloue

    1. , Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique Centre Versailles, F-78026 Versailles Cedex, France,, Institut Biologie II, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany, and, Biology Department, University of Waterloo, ON, Canada N2L 3G1
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Summary

Adenosine kinase (adk) from the moss Physcomitrella patens (Hedw.) B.S.G. was cloned from a cDNA library by functional complementation of an Escherichia coli purine auxotrophic strain. The length of the entire cDNA clone was 1175 bp with an open reading frame coding for a protein with a predicted molecular weight of 37.3 kDa. Southern analysis indicated the presence of a single adenosine kinase gene within the Physcomitrella genome. The deduced amino acid sequence had a 52% identity with the human adenosine kinase. The transfer of phosphate from ATP to adenosine resulting in AMP, as well as the phosphorylation of the cytokinin, isopentenyladenosine, to isopentenyladenosine monophosphate, was shown by in vitro enzyme assays using crude extracts from E. coli mutants expressing the adk cDNA clone and from Physcomitrella chloronemal tissue. Results from in vivo feeding of chloronemal tissue with tritiated isopentenyladenosine suggest that adenosine kinase plays an important role in the conversion of cytokinins towards their nucleotides in Physcomitrella.

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