title: Soluble starch synthase I: a major determinant for the synthesis of amylopectin in Arabidopsis thaliana leaves.
abstract: A minimum of four soluble starch synthase families have been documented in all starch-storing green plants. These activities are involved in amylopectin synthesis and are extremely well conserved throughout the plant kingdom. Mutants or transgenic plants defective for SSII and SSIII isoforms have been previously shown to have a large and specific impact on the synthesis of amylopectin while the function of the SSI type of enzymes has remained elusive. We report here that Arabidopsis mutants, lacking a plastidial starch synthase isoform belonging to the SSI family, display a major and novel type of structural alteration within their amylopectin. Comparative analysis of beta-limit dextrins for both wild type and mutant amylopectins suggests a specific and crucial function of SSI during the synthesis of transient starch in Arabidopsis leaves. Considering our own characterization of SSI activity and the previously described kinetic properties of maize SSI, our results suggest that the function of SSI is mainly involved in the synthesis of small outer chains during amylopectin cluster synthesis.
authors.affiliation: Unité de Glycobiologie Structurale et Fonctionnelle, UMR8576 CNRS/USTL, IFR 118, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France.
authors.forename: David
authors.initials: D
authors.lastname: Delvallé
authors.forename: Sylvain
authors.initials: S
authors.lastname: Dumez
authors.forename: Fabrice
authors.initials: F
authors.lastname: Wattebled
authors.forename: Isaac
authors.initials: I
authors.lastname: Roldán
authors.forename: Véronique
authors.initials: V
authors.lastname: Planchot
authors.forename: Pierre
authors.initials: P
authors.lastname: Berbezy
authors.forename: Paul
authors.initials: P
authors.lastname: Colonna
authors.forename: Darshna
authors.initials: D
authors.lastname: Vyas
authors.forename: Manash
authors.initials: M
authors.lastname: Chatterjee
authors.forename: Steven
authors.initials: S
authors.lastname: Ball
authors.forename: Angel
authors.initials: A
authors.lastname: Mérida
authors.forename: Christophe
authors.initials: C
authors.lastname: D'Hulst
mesh_terms: D000687:Amylopectin / Q000096:biosynthesis*; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D002850:Chromatography, Gel; D002874:Chromosome Mapping; D004926:Escherichia coli / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D010641:Phenotype; D018515:Plant Leaves / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013214:Starch Synthase / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D000687:Amylopectin; D013214:Starch Synthase