Journal Article

A Cell Wall-Bound Adenosine Nucleosidase is Involved in the Salvage of Extracellular ATP in <i>Solanum tuberosum</i>

David Riewe, Lukasz Grosman, Alisdair R. Fernie, Henrik Zauber, Cornelia Wucke and Peter Geigenberger

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 49, issue 10, pages 1572-1579
Published in print October 2008 | ISSN: 0032-0781
Published online September 2008 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcn127
A Cell Wall-Bound Adenosine Nucleosidase is Involved in the Salvage of Extracellular ATP in Solanum tuberosum

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Extracellular ATP (eATP) has recently been demonstrated to play a crucial role in plant development and growth. To investigate the fate of eATP within the apoplast, we used intact potato (Solanum tuberosum) tuber slices as an experimental system enabling access to the apoplast without interference of cytosolic contamination. (i) Incubation of intact tuber slices with ATP led to the formation of ADP, AMP, adenosine, adenine and ribose, indicating operation of apyrase, 5′-nucleotidase and nucleosidase. (ii) Measurement of apyrase, 5′-nucleotidase and nucleosidase activities in fractionated tuber tissue confirmed the apoplastic localization for apyrase and phosphatase in potato and led to the identification of a novel cell wall-bound adenosine nucleosidase activity. (iii) When intact tuber slices were incubated with saturating concentrations of adenosine, the conversion of adenosine into adenine was much higher than adenosine import into the cell, suggesting a potential bypass of adenosine import. Consistent with this, import of radiolabeled adenine into tuber slices was inhibited when ATP, ADP or AMP were added to the slices. (iv) In wild-type plants, apyrase and adenosine nucleosidase activities were found to be co-regulated, indicating functional linkage of these enzymes in a shared pathway. (v) Moreover, adenosine nucleosidase activity was reduced in transgenic lines with strongly reduced apoplastic apyrase activity. When taken together, these results suggest that a complete ATP salvage pathway is present in the apoplast of plant cells.

Keywords: Adenosine nucleosidase; Apoplast; Apyrase; Cell wall; Extracellular ATP; Solanum tuberosum

Journal Article.  4973 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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