Journal Article

Decreased expression of plastidial adenylate kinase in potato tubers results in an enhanced rate of respiration and a stimulation of starch synthesis that is attributable to post-translational redox-activation of ADP-glucose pyrophosphorylase

Sandra N. Oliver, Axel Tiessen, Alisdair R. Fernie and Peter Geigenberger

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 2, pages 315-325
Published in print February 2008 | ISSN: 0022-0957
Published online February 2008 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/erm312

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Adenine nucleotides are of general importance for many aspects of cell function, but their role in the regulation of biosynthetic processes is still unclear. It was previously reported that decreased expression of plastidial adenylate kinase, catalysing the interconversion of ATP and AMP to ADP, leads to increased adenylate pools and starch content in transgenic potato tubers. However, the underlying mechanisms were not elucidated. Here, it is shown that decreased expression of plastidial adenylate kinase in growing tubers leads to increased rates of respiratory oxygen consumption and increased carbon fluxes into starch. Increased rates of starch synthesis were accompanied by post-translational redox-activation of ADP-glucose pyrophosphorylase (AGPase), catalysing the key regulatory step of starch synthesis in the plastid, while there were no substantial changes in metabolic intermediates or sugar levels. A similar increase in post-translational redox-activation of AGPase was found after supplying adenine to wild-type potato tuber discs to increase adenine nucleotide levels. Results provide first evidence for a link between redox-activation of AGPase and adenine nucleotide levels in plants.

Keywords: Adenylate kinase; ADPglucose pyrophosphorylase; plastid; redox-regulation; potato; respiration; starch

Journal Article.  6029 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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