CP12 Is Involved in Protection against High Light Intensity by Suppressing the ROS Generation in Synechococcus elongatus PCC7942.

Masahiro Tamoi,Shigeru Shigeoka

doi:10.3390/plants10071275

Masahiro Tamoi, Shigeru Shigeoka

Open Access

https://doi.org/10.3390/plants10071275

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Journal: Plants (Basel, Switzerland)	Publication Date: Jun 23, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: Kindai University

Abstract

We previously reported that CP12 formed a complex with GAPDH and PRK and regulated the activities of these enzymes and the Calvin–Benson cycle under dark conditions as the principal regulatory system in cyanobacteria. More interestingly, we found that the cyanobacterial CP12 gene-disrupted strain was more sensitive to photo-oxidative stresses such as under high light conditions and paraquat treatment. When a mutant strain that grew normally under low light was subjected to high light conditions, decreases in chlorophyll and photosynthetic activity were observed. Furthermore, a large amount of ROS was accumulated in the cells of the CP12 gene-disrupted strain. These data suggest that CP12 also functions under light conditions and may be involved in protection against oxidative stress by controlling the flow of electrons from Photosystem I to NADPH.

Highlights

Oxygenic photosynthesis by plants, algae, and cyanobacteria converts sunlight into chemical energy, essential for their metabolism
It has been clarified that the enzymes constituting the cyanobacterial Calvin–Benson cycle are not regulated by the Fd/Trx system, unlike those derived from higher plants [3]
It has already reported that Sc∆CP12 grows like the WT at 40 μmol photons m−2 s−1 in Tamoi et al 2005 [9]

Summary

Introduction

Algae, and cyanobacteria converts sunlight into chemical energy, essential for their metabolism. In the Calvin–Benson cycle, the activities of thiol-modulated enzymes, such as NADP+ -glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fructose1,6-bisphosphatase (FBPase), sedoheptulose-1,7-bisphosphatase (SBPase), and phosphoribulokinase (PRK), are activated by the reduction of intramolecular disulfide bridges via the ferredoxin/thioredoxin (Fd/Trx) system during the day [1,2]. When these cysteine residues of the four enzymes are oxidized to form a disulfide bond, they change to the inactive form during the night. It was reported that carbon metabolism could be regulated through controlling the activity of these enzymes by associating/dissociating a complex in cyanobacteria [9]

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Conclusion