Circadian clock regulation of starch metabolism establishes GBSSI as a major contributor to amylopectin synthesis in Chlamydomonas reinhardtii

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DOI

Resolve DOI: https://doi.org/10.1104/pp.106.081885

Author

Search for: Ral, Jean-Philippe; Search for: Colleoni, Christophe; Search for: Wattebled, Fabrice; Search for: Dauvillée, David; Search for: Nempont, Clément; Search for: Deschamps, Philippe; Search for: Li, Zhongyi; Search for: Morell, Matthew K.; Search for: Chibbar, Ravindra¹; Search for: Purton, Saul; Search for: d'Hulst, Christophe¹; Search for: Ball, Steven G.

Affiliation

National Research Council Canada. NRC Plant Biotechnology Institute

Format

Text, Article

Abstract

Chlamydomonas reinhardtii displays a diurnal rhythm of starch content that peaks in the middle of the night phase if the algae are provided with acetate and CO2 as a carbon source. We show that this rhythm is controlled by the circadian clock and is tightly correlated to ADP-glucose pyrophosphorylase activity. Persistence of this rhythm depends on the presence of either soluble starch synthase III or granule-bound starch synthase I (GBSSI). We show that both enzymes play a similar function in synthesizing the long glucan fraction that interconnects the amylopectin clusters. We demonstrate that in log phase-oscillating cultures, GBSSI is required to obtain maximal polysaccharide content and fully compensates for the loss of soluble starch synthase III. A point mutation in the GBSSI gene that prevents extension of amylopectin chains, but retains the enzyme's normal ability to extend maltooligosaccharides, abolishes the function of GBSSI both in amylopectin and amylose synthesis and leads to a decrease in starch content in oscillating cultures. We propose that GBSSI has evolved as a major enzyme of amylopectin synthesis and that amylose synthesis comes as a secondary consequence of prolonged synthesis by GBSSI in arrhythmic systems. Maintenance in higher plant leaves of circadian clock control of GBSSI transcription is discussed.

Publication date

2006-09-06

Publisher

Oxford University Press

Licence

Creative Commons, Attribution 4.0 International (CC BY 4.0)
https://creativecommons.org/licenses/by/4.0/

Language

English

Peer reviewed

Yes

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Record identifier

bce4f6de-856d-43c1-ae8b-2f700d1d7b0c

Record created

2023-06-13

Record modified

2023-06-14

Date modified:: 2026-01-16