title: The heterotrophic dinoflagellate Crypthecodinium cohnii defines a model genetic system to investigate cytoplasmic starch synthesis.
abstract: The nature of the cytoplasmic pathway of starch biosynthesis was investigated in the model heterotrophic dinoflagellate Crypthecodinium cohnii. The storage polysaccharide granules were shown to be composed of both amylose and amylopectin fractions with a chain length distribution and crystalline organization very similar to those of green algae and land plant starch. Preliminary characterization of the starch pathway demonstrated that C. cohnii contains multiple forms of soluble starch synthases and one major 110-kDa granule-bound starch synthase. All purified enzymes displayed a marked substrate preference for UDP-glucose. At variance with most other microorganisms, the accumulation of starch in the dinoflagellate occurs during early and mid-log phase, with little or no synthesis witnessed when approaching stationary phase. In order to establish a genetic system allowing the study of cytoplasmic starch metabolism in eukaryotes, we describe the isolation of marker mutations and the successful selection of random recombinant populations after homothallic crosses.
authors.affiliation: CNRS, UMR8576, USTL, Cité Scientifique, 59655 Villeneuve d'Ascq, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Deschamps
authors.forename: Delphine
authors.initials: D
authors.lastname: Guillebeault
authors.forename: Jimi
authors.initials: J
authors.lastname: Devassine
authors.forename: David
authors.initials: D
authors.lastname: Dauvillée
authors.forename: Sophie
authors.initials: S
authors.lastname: Haebel
authors.forename: Martin
authors.initials: M
authors.lastname: Steup
authors.forename: Alain
authors.initials: A
authors.lastname: Buléon
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Putaux
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Slomianny
authors.forename: Christophe
authors.initials: C
authors.lastname: Colleoni
authors.forename: Aline
authors.initials: A
authors.lastname: Devin
authors.forename: Charlotte
authors.initials: C
authors.lastname: Plancke
authors.forename: Stanislas
authors.initials: S
authors.lastname: Tomavo
authors.forename: Evelyne
authors.initials: E
authors.lastname: Derelle
authors.forename: Hervé
authors.initials: H
authors.lastname: Moreau
authors.forename: Steven
authors.initials: S
authors.lastname: Ball
mesh_terms: D020418:Algal Proteins / Q000032:analysis / Q000378:metabolism; D000818:Animals; D003433:Crosses, Genetic; D003593:Cytoplasm / Q000378:metabolism*; D004141:Dinoflagellida / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D052836:Heterotrophic Processes; D008957:Models, Genetic; D016296:Mutagenesis; D015800:Protozoan Proteins / Q000032:analysis / Q000378:metabolism; D011995:Recombination, Genetic; D013213:Starch / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D024941:Starch Phosphorylase / Q000032:analysis / Q000378:metabolism; D013214:Starch Synthase / Q000032:analysis / Q000378:metabolism; D014532:Uridine Diphosphate Glucose / Q000378:metabolism
chemical_list: D020418:Algal Proteins; D015800:Protozoan Proteins; D013213:Starch; D024941:Starch Phosphorylase; C434607:granule-bound starch synthase I; D013214:Starch Synthase; D014532:Uridine Diphosphate Glucose