A1 Refereed original research article in a scientific journal

Glycogen synthesis prevents metabolic imbalance and disruption of photosynthetic electron transport from photosystem II during transition to photomixotrophy in Synechocystis sp PCC 6803



Authors: Ortega-Martínez Pablo, Nikkanen Lauri, Wey Laura T., Florencio Francisco J., Allahverdiyeva Yagut, Díaz-Troya Sandra

Publisher: John Wiley & Sons

Publication year: 2024

Journal: New Phytologist

Journal name in source: The New phytologist

Journal acronym: New Phytol

Volume: 243

Issue: 1

First page : 162

Last page: 179

ISSN: 0028-646X

eISSN: 1469-8137

DOI: https://doi.org/10.1111/nph.19793

Web address : https://doi.org/10.1111/nph.19793

Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/393474740


Abstract
Some cyanobacteria can grow photoautotrophically or photomixotrophically by using simultaneously CO2 and glucose. The switch between these trophic modes and the role of glycogen, their main carbon storage macromolecule, was investigated. We analysed the effect of glucose addition on the physiology, metabolic and photosynthetic state of Synechocystis sp. PCC 6803 and mutants lacking phosphoglucomutase and ADP-glucose pyrophosphorylase, with limitations in glycogen synthesis. Glycogen acted as a metabolic buffer: glucose addition increased growth and glycogen reserves in the wild-type (WT), but arrested growth in the glycogen synthesis mutants. Already 30 min after glucose addition, metabolites from the Calvin-Benson-Bassham cycle and the oxidative pentose phosphate shunt increased threefold more in the glycogen synthesis mutants than the WT. These alterations substantially affected the photosynthetic performance of the glycogen synthesis mutants, as O2 evolution and CO2 uptake were both impaired. We conclude that glycogen synthesis is essential during transitions to photomixotrophy to avoid metabolic imbalance that induces inhibition of electron transfer from PSII and subsequently accumulation of reactive oxygen species, loss of PSII core proteins, and cell death. Our study lays foundations for optimising photomixotrophy-based biotechnologies through understanding the coordination of the crosstalk between photosynthetic electron transport and metabolism.

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Last updated on 2025-17-03 at 14:15