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Eukaryotic Cell, February 2008, p. 247-257, Vol. 7, No. 2
1535-9778/08/$08.00+0 doi:10.1128/EC.00373-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Philippe Deschamps,1,
David Dauvillée,1
Yasunori Nakamura,2
Sophie Haebel,3
Gehrardt Ritte,4
Martin Steup,4
Alain Buléon,5
Jean-Luc Putaux,6
Danielle Dupeyre,6
Christophe d'Hulst,1
Jean-Philippe Ral,1,
Wolfgang Löffelhardt,7 and
Steven G. Ball1*
Unité de Glycobiologie Structurale et Fonctionnelle, UMR8576 CNRS/USTL, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, Cedex 59655, France,1 Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-Nakano, Akita 010-0195, Japan,2 Center of Mass Spectrometry of Biopolymers,3 Plant Physiology, Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany,4 Institut National de la Recherche Agronomique, Centre de Recherches Agroalimentaires, Rue de la Géraudière, BP71627, 44316 Nantes, Cedex 03, France,5 Centre de Recherches sur les Macromolécules Végétales (CERMAV-CNRS), BP 53, F-38041 Grenoble, Cedex 9, France,6 Max F. Perutz Laboratories, University of Vienna, Department of Biochemistry, Dr. Bohrgasse 9, 1030 Vienna, Austria7
Received 9 October 2007/ Accepted 23 November 2007
The nature of the cytoplasmic pathway of starch biosynthesis was investigated in the model glaucophyte Cyanophora paradoxa. The storage polysaccharide granules are shown to be composed of both amylose and amylopectin fractions, with a chain length distribution and crystalline organization similar to those of green algae and land plant starch. A preliminary characterization of the starch pathway demonstrates that Cyanophora paradoxa contains several UDP-glucose-utilizing soluble starch synthase activities related to those of the Rhodophyceae. In addition, Cyanophora paradoxa synthesizes amylose with a granule-bound starch synthase displaying a preference for UDP-glucose. A debranching enzyme of isoamylase specificity and multiple starch phosphorylases also are evidenced in the model glaucophyte. The picture emerging from our biochemical and molecular characterizations consists of the presence of a UDP-glucose-based pathway similar to that recently proposed for the red algae, the cryptophytes, and the alveolates. The correlative presence of isoamylase and starch among photosynthetic eukaryotes is discussed.
Published ahead of print on 30 November 2007.
These authors contributed equally to this work.
Present address: CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia.
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