Starch division and partitioning. A mechanism for granule propagation and maintenance in the picophytoplanktonic green alga Ostreococcus tauri

• Published in: Plant physiology (Bethesda) 2004-10, Vol.136 (2), p.3333-3340
• Main Authors: Ral, J.P, Derelle, E, Ferraz, C, Wattebled, F, Farinas, B, Corellou, F, Buleon, A, Slomianny, M.C, Delvalle, D, d'Hulst, C
• Format: Article
• Language: English
• Subjects: adenosine diphosphate; Adenosine Diphosphate Glucose - metabolism; Algae; algae and seaweeds; biochemical pathways; Biochemistry; Biochemistry, Molecular Biology; Biological and medical sciences; carbohydrate metabolism; carbohydrate structure; cell cycle; Cell Cycle - physiology; Chlorophycota; Chlorophyta - cytology; Chlorophyta - metabolism; Chlorophyta - ultrastructure; Chloroplasts - metabolism; Cytoplasmic Granules - metabolism; Enzymes; Evolution; Fundamental and applied biological sciences. Psychology; Genetics, Genomics, and Molecular Evolution; Genome; Genomes; glucose; Glycogen; Life Sciences; Metabolism; Molecular Sequence Data; Ostreococcus tauri; Photosynthesis, respiration. Anabolism, catabolism; Phylogeny; Plant cells; Plant physiology and development; Plants; Plastids; Polysaccharides; Prasinophyceae; Starch - biosynthesis; starch granules; Starch Synthase - genetics; Starch Synthase - metabolism; Starches
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.104.044131

Whereas Glc is stored in small-sized hydrosoluble glycogen particles in archaea, eubacteria, fungi, and animal cells, photosynthetic eukaryotes have resorted to building starch, which is composed of several distinct polysaccharide fractions packed into a highly organized semicrystalline granule. In plants, both the initiation of polysaccharide synthesis and the nucleation mechanism leading to formation of new starch granules are currently not understood. Ostreococcus tauri, a unicellular green alga of the Prasinophyceae family, defines the tiniest eukaryote with one of the smallest genomes. We show that it accumulates a single starch granule at the chloroplast center by using the same pathway as higher plants. At the time of plastid division, we observe elongation of the starch and division into two daughter structures that are partitioned in each newly formed chloroplast. These observations suggest that in this system the information required to initiate crystalline polysaccharide growth of a new granule is contained within the preexisting polysaccharide structure and the design of the plastid division machinery.