Pathway of cytosolic starch synthesis in the model glaucophyte Cyanophora paradoxa.
Eukaryot Cell
; 7(2): 247-57, 2008 Feb.
Article
em En
| MEDLINE
| ID: mdl-18055913
ABSTRACT
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.
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Amido
/
Sintase do Amido
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Uridina Difosfato Glucose
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Amido Fosforilase
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Citosol
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Cyanophora
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Modelos Biológicos
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article