An ATP-sensitive phosphoketolase regulates carbon fixation in cyanobacteria

Lu, Kuan-Jen; Chang, Chiung‐Wen; Wang, Chun-Hsiung; Chen, Frederic Y.-H.; Huang, I-Shen; Huang, Po-Yuan; Yang, Cheng‐Han; Wu, Hsiang-Yi; Wu, Wen‐Jin; Hsu, Kai‐Cheng; Ho, Meng-Chiao; Tsai, Ming‐Daw; Liao, James C.

doi:10.21203/rs.3.rs-2369262/v1

Cited by 3 publications

(3 citation statements)

References 39 publications

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“…When ATP level lowers upon cell entering the dark 25 , phosphoketolase can be activated to catalyze X5P cleavage. A more recent report confirmed the allosteric regulation of phosphoketolase by ATP, and further showed an increased phosphoketolase activity during lightdark transitions to brake on the CBB cycle and switch cell metabolism into respiration 26 .…”

Section: Discussionmentioning

confidence: 68%

Dark respiration modulates photosynthetic carbon yield in cyanobacteria

Xie,

Sharma,

Rusche

et al. 2024

Preprint

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Cyanobacteria contribute to roughly a quarter of global net carbon fixation. During diel light/dark growth, dark respiration significantly lowers the overall photosynthetic carbon yield in cyanobacteria and other phototrophs. Currently, it is unclear how photosynthetic organisms allocate carbon resources at night for optimal dark survival. Here we show in the cyanobacterium Synechococcus elongatus PCC 7942 that phosphoketolase and 2-keto-3-deoxy-6-phosphogluconate (KDPG) aldolase are orchestrated in an integrative respiratory network in the dark to best allocate carbon resource for amino acid synthesis and preparation for photosynthesis reinitiation upon photoinduction. We further show that the Entner-Doudoroff (ED) pathway is incomplete in S. elongatus with the KDPG aldolase participating in dark respiration through an alternative decarboxylation activity. Optimization of dark respiration thus represents a unique strategy to enhance photosynthetic carbon yield in cyanobacteria and other photosynthetic organisms.

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Section: Discussionmentioning

confidence: 68%

Dark respiration modulates photosynthetic carbon yield in cyanobacteria

Xie,

Sharma,

Rusche

et al. 2024

Preprint

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“…Notably, at the optimal concentration of CDs (40 mg L −1 ), the growth rate of Syne cells reached 0.1 h −1 during the exponential growth phase, which was 1.5-fold higher than that of the control group without CDs. As photoautotrophs, Syne cells fix and convert CO 2 into biomass, and they derive energy from photosynthesis for CO 2 fixation and biomass formation 51 . Thus, our results suggest that the CDs enhance the photosystem activity and CO 2 fixation of Syne cells.…”

Section: Resultsmentioning

confidence: 99%

Enhancing Plant Photosynthesis using Carbon Dots as Light Converter and Photosensitizer

Hu,

Cheng,

Wang

et al. 2024

Preprint

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Improving photosynthetic efficiency is pivotal for CO2-based biomanufacturing and agriculture purposes. Despite the progress on photosynthetic biohybrids integrating biocatalysts with synthetic materials, nanomaterials with improved optical and photoelectrochemical properties are still needed to increase the energy-conversion efficiency. Here, we present a novel approach using carbon dots (CDs) as both intracellular photosensitizers and light converters for enhancing solar energy utilization in photosynthetic organisms. The CDs were produced from cyanobacterial biomass and used to convert a broad spectrum of solar irradiation to red light. We demonstrated that the nanosized CDs were incorporated into cyanobacterial cells and transferred light-excited electrons into the photosynthetic electron transfer chain. The biohybrids consisting of the CDs andSynechococcus elongatusexhibited increased growth rates, enhanced activities of both photosystems, and accelerated linear electron transport, compared with the cyanobacterial cells only. The supplementation of the CDs increased CO2-fixation rate and CO2-to-glycerol production by 2.4-fold and 2.2-fold, respectively. Furthermore, the CDs were shown to enhance photosynthesis and promote growth ofArabidopsis thaliana. The fresh weight of plant was increased 1.8-fold by CDs addition. These results reveal that simultaneous photosensitization and spectral modification could substantially improve the efficiency of natural photosynthesis. This study presents CDs as an attractive nanomaterial with great application potential in agriculture and solar-powered biomanufacturing.

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“…In dark heterotrophic conditions, PK is necessary for acetate production from exogenous sugars (Xiong et al, 2015). Recently, it has been revealed that the consumption of sugar phosphates by PK immediately after the light-to-dark transition halts the CBB cycle (Lu et al, 2023). The GAP generated by PK potentially contributes to the accumulation of glycolytic acid intermediates.…”

Section: Discussionmentioning

confidence: 99%

Minimized dark cataplerosis of the Calvin cycle ensures prompt photosynthetic initiation in cyanobacteria

Tanaka,

Kondo,

Hasunuma

2023

Preprint

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As primary contributors to oxygenic photosynthesis, cyanobacteria intricately regulate their metabolic pathways during the diurnal cycle to ensure survival and growth. Under dark conditions, breakdown of stored energy reserves of glycogen replenishes the intermediates, especially the downstream glycolytic metabolites necessary for photosynthetic initiation upon light irradiation. The intracellular level of the intermediates is maintained throughout the dark period. However, it remains unclear how their accumulation is maintained in the dark despite the limited availability of glycogen. Here, we showed that the metabolite accumulation stability is ensured by the low activities of phosphoenolpyruvate (PEP) converting enzymes, namely PEP carboxylase and pyruvate kinase, during the dark period. Overexpression of these enzymes significantly decreased the accumulation of glycolytic intermediates after dark incubation. The oxygen evolution ability simultaneously decreased in the overexpressing strains, indicating that the dark limitation of the PEP-consuming pathway facilitates photosynthetic initiation through the maintenance of glycolytic intermediates. This finding shed light on the importance of controlling cataplerotic flux during the dark for maintaining stable operation of the Calvin cycle.

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An ATP-sensitive phosphoketolase regulates carbon fixation in cyanobacteria

Cited by 3 publications

References 39 publications

Dark respiration modulates photosynthetic carbon yield in cyanobacteria

Dark respiration modulates photosynthetic carbon yield in cyanobacteria

Enhancing Plant Photosynthesis using Carbon Dots as Light Converter and Photosensitizer

Minimized dark cataplerosis of the Calvin cycle ensures prompt photosynthetic initiation in cyanobacteria

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