1
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Cantrell M, Ware MA, Peers G. Characterizing compensatory mechanisms in the absence of photoprotective qE in Chlamydomonas reinhardtii. PHOTOSYNTHESIS RESEARCH 2023; 158:23-39. [PMID: 37488319 DOI: 10.1007/s11120-023-01037-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 06/26/2023] [Indexed: 07/26/2023]
Abstract
Rapid fluctuations in the quantity and quality of natural light expose photosynthetic organisms to conditions when the capacity to utilize absorbed quanta is insufficient. These conditions can result in the production of reactive oxygen species and photooxidative damage. Non-photochemical quenching (NPQ) and alternative electron transport are the two most prominent mechanisms which synergistically function to minimize the overreduction of photosystems. In the green alga Chlamydomonas reinhardtii, the stress-related light-harvesting complex (LHCSR) is a required component for the rapid induction and relaxation of NPQ in the light-harvesting antenna. Here, we use simultaneous chlorophyll fluorescence and oxygen exchange measurements to characterize the acclimation of the Chlamydomonas LHCSR-less mutant (npq4lhcsr1) to saturating light conditions. We demonstrate that, in the absence of NPQ, Chlamydomonas does not acclimate to sinusoidal light through increased light-dependent oxygen consumption. We also show that the npq4lhcsr1 mutant has an increased sink capacity downstream of PSI and this energy flow is likely facilitated by cyclic electron transport. Furthermore, we show that the timing of additions of mitochondrial inhibitors has a major influence on plastid/mitochondrial coupling experiments.
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Affiliation(s)
- Michael Cantrell
- Department of Biology, Colorado State University, Fort Collins, CO, USA
| | - Maxwell A Ware
- Department of Biology, Colorado State University, Fort Collins, CO, USA
| | - Graham Peers
- Department of Biology, Colorado State University, Fort Collins, CO, USA.
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2
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Cao T, Bai Y, Buschbeck P, Tan Q, Cantrell MB, Chen Y, Jiang Y, Liu RZ, Ries NK, Shi X, Sun Y, Ware MA, Yang F, Zhang H, Han J, Zhang L, Huang J, Lohr M, Peers G, Li X. An unexpected hydratase synthesizes the green light-absorbing pigment fucoxanthin. THE PLANT CELL 2023; 35:3053-3072. [PMID: 37100425 PMCID: PMC10396388 DOI: 10.1093/plcell/koad116] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 04/05/2023] [Accepted: 04/06/2023] [Indexed: 06/19/2023]
Abstract
The ketocarotenoid fucoxanthin and its derivatives can absorb blue-green light enriched in marine environments. Fucoxanthin is widely adopted by phytoplankton species as a main light-harvesting pigment, in contrast to land plants that primarily employ chlorophylls. Despite its supreme abundance in the oceans, the last steps of fucoxanthin biosynthesis have remained elusive. Here, we identified the carotenoid isomerase-like protein CRTISO5 as the diatom fucoxanthin synthase that is related to the carotenoid cis-trans isomerase CRTISO from land plants but harbors unexpected enzymatic activity. A crtiso5 knockout mutant in the model diatom Phaeodactylum tricornutum completely lacked fucoxanthin and accumulated the acetylenic carotenoid phaneroxanthin. Recombinant CRTISO5 converted phaneroxanthin into fucoxanthin in vitro by hydrating its carbon-carbon triple bond, instead of functioning as an isomerase. Molecular docking and mutational analyses revealed residues essential for this activity. Furthermore, a photophysiological characterization of the crtiso5 mutant revealed a major structural and functional role of fucoxanthin in photosynthetic pigment-protein complexes of diatoms. As CRTISO5 hydrates an internal alkyne physiologically, the enzyme has unique potential for biocatalytic applications. The discovery of CRTISO5 illustrates how neofunctionalization leads to major diversification events in evolution of photosynthetic mechanisms and the prominent brown coloration of most marine photosynthetic eukaryotes.
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Affiliation(s)
- Tianjun Cao
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Yu Bai
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Paul Buschbeck
- Institut für Molekulare Physiologie, Johannes Gutenberg-University, 55099 Mainz, Germany
| | - Qiaozhu Tan
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China
| | - Michael B Cantrell
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Yinjuan Chen
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Instrumentation and Service Center for Molecular Sciences, Westlake University, Hangzhou 310024, China
| | - Yanyou Jiang
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China
| | - Run-Zhou Liu
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, Hangzhou 310024, China
| | - Nana K Ries
- Institut für Molekulare Physiologie, Johannes Gutenberg-University, 55099 Mainz, Germany
| | - Xiaohuo Shi
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Instrumentation and Service Center for Molecular Sciences, Westlake University, Hangzhou 310024, China
| | - Yan Sun
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315211, China
| | - Maxwell A Ware
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Fenghua Yang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China
| | - Huan Zhang
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Jichang Han
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315211, China
| | - Lihan Zhang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, Hangzhou 310024, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Jing Huang
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou 310024, China
| | - Martin Lohr
- Institut für Molekulare Physiologie, Johannes Gutenberg-University, 55099 Mainz, Germany
| | - Graham Peers
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Xiaobo Li
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, China
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3
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Li R, He Y, Chen J, Zheng S, Zhuang C. Research Progress in Improving Photosynthetic Efficiency. Int J Mol Sci 2023; 24:ijms24119286. [PMID: 37298238 DOI: 10.3390/ijms24119286] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/12/2023] Open
Abstract
Photosynthesis is the largest mass- and energy-conversion process on Earth, and it is the material basis for almost all biological activities. The efficiency of converting absorbed light energy into energy substances during photosynthesis is very low compared to theoretical values. Based on the importance of photosynthesis, this article summarizes the latest progress in improving photosynthesis efficiency from various perspectives. The main way to improve photosynthetic efficiency is to optimize the light reactions, including increasing light absorption and conversion, accelerating the recovery of non-photochemical quenching, modifying enzymes in the Calvin cycle, introducing carbon concentration mechanisms into C3 plants, rebuilding the photorespiration pathway, de novo synthesis, and changing stomatal conductance. These developments indicate that there is significant room for improvement in photosynthesis, providing support for improving crop yields and mitigating changes in climate conditions.
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Affiliation(s)
- Ruiqi Li
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Ying He
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Junyu Chen
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Shaoyan Zheng
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Chuxiong Zhuang
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
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4
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Suwannachuen N, Leetanasaksakul K, Roytrakul S, Phaonakrop N, Thaisakun S, Roongsattham P, Jantasuriyarat C, Sanevas N, Sirikhachornkit A. Palmelloid Formation and Cell Aggregation Are Essential Mechanisms for High Light Tolerance in a Natural Strain of Chlamydomonas reinhardtii. Int J Mol Sci 2023; 24:ijms24098374. [PMID: 37176080 PMCID: PMC10179368 DOI: 10.3390/ijms24098374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/01/2023] [Accepted: 05/05/2023] [Indexed: 05/15/2023] Open
Abstract
Photosynthetic organisms, such as higher plants and algae, require light to survive. However, an excessive amount of light can be harmful due to the production of reactive oxygen species (ROS), which cause cell damage and, if it is not effectively regulated, cell death. The study of plants' responses to light can aid in the development of methods to improve plants' growth and productivity. Due to the multicellular nature of plants, there may be variations in the results based on plant age and tissue type. Chlamydomonas reinhardtii, a unicellular green alga, has also been used as a model organism to study photosynthesis and photoprotection. Nonetheless, the majority of the research has been conducted with strains that have been consistently utilized in laboratories and originated from the same source. Despite the availability of many field isolates of this species, very few studies have compared the light responses of field isolates. This study examined the responses of two field isolates of Chlamydomonas to high light stress. The light-tolerant strain, CC-4414, managed reactive oxygen species (ROS) slightly better than the sensitive strain, CC-2344, did. The proteomic data of cells subjected to high light revealed cellular modifications of the light-tolerant strain toward membrane proteins. The morphology of cells under light stress revealed that this strain utilized the formation of palmelloid structures and cell aggregation to shield cells from excessive light. As indicated by proteome data, morphological modifications occur simultaneously with the increase in protein degradation and autophagy. By protecting cells from stress, cells are able to continue to upregulate ROS management mechanisms and prevent cell death. This is the first report of palmelloid formation in Chlamydomonas under high light stress.
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Affiliation(s)
- Nittaya Suwannachuen
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Bangkok 10900, Thailand
| | - Kantinan Leetanasaksakul
- Functional Proteomics Technology Laboratory, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Paholyothin Road, Klong 1, Klong Luang, Pathum Thani 12120, Thailand
| | - Sittiruk Roytrakul
- Functional Proteomics Technology Laboratory, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Paholyothin Road, Klong 1, Klong Luang, Pathum Thani 12120, Thailand
| | - Narumon Phaonakrop
- Functional Proteomics Technology Laboratory, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Paholyothin Road, Klong 1, Klong Luang, Pathum Thani 12120, Thailand
| | - Siriwan Thaisakun
- Functional Proteomics Technology Laboratory, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Paholyothin Road, Klong 1, Klong Luang, Pathum Thani 12120, Thailand
| | - Peerapat Roongsattham
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Bangkok 10900, Thailand
| | - Chatchawan Jantasuriyarat
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Bangkok 10900, Thailand
| | - Nuttha Sanevas
- Department of Botany, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Anchalee Sirikhachornkit
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Bangkok 10900, Thailand
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5
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Advances in Genetic Engineering in Improving Photosynthesis and Microalgal Productivity. Int J Mol Sci 2023; 24:ijms24031898. [PMID: 36768215 PMCID: PMC9915242 DOI: 10.3390/ijms24031898] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/10/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Even though sunlight energy far outweighs the energy required by human activities, its utilization is a key goal in the field of renewable energies. Microalgae have emerged as a promising new and sustainable feedstock for meeting rising food and feed demand. Because traditional methods of microalgal improvement are likely to have reached their limits, genetic engineering is expected to allow for further increases in the photosynthesis and productivity of microalgae. Understanding the mechanisms that control photosynthesis will enable researchers to identify targets for genetic engineering and, in the end, increase biomass yield, offsetting the costs of cultivation systems and downstream biomass processing. This review describes the molecular events that happen during photosynthesis and microalgal productivity through genetic engineering and discusses future strategies and the limitations of genetic engineering in microalgal productivity. We highlight the major achievements in manipulating the fundamental mechanisms of microalgal photosynthesis and biomass production, as well as promising approaches for making significant contributions to upcoming microalgal-based biotechnology.
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6
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Steen CJ, Burlacot A, Short AH, Niyogi KK, Fleming GR. Interplay between LHCSR proteins and state transitions governs the NPQ response in Chlamydomonas during light fluctuations. PLANT, CELL & ENVIRONMENT 2022; 45:2428-2445. [PMID: 35678230 PMCID: PMC9540987 DOI: 10.1111/pce.14372] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/27/2022] [Accepted: 05/28/2022] [Indexed: 05/19/2023]
Abstract
Photosynthetic organisms use sunlight as the primary energy source to fix CO2 . However, in nature, light energy is highly variable, reaching levels of saturation for periods ranging from milliseconds to hours. In the green microalga Chlamydomonas reinhardtii, safe dissipation of excess light energy by nonphotochemical quenching (NPQ) is mediated by light-harvesting complex stress-related (LHCSR) proteins and redistribution of light-harvesting antennae between the photosystems (state transition). Although each component underlying NPQ has been documented, their relative contributions to NPQ under fluctuating light conditions remain unknown. Here, by monitoring NPQ in intact cells throughout high light/dark cycles of various illumination periods, we find that the dynamics of NPQ depend on the timescales of light fluctuations. We show that LHCSRs play a major role during the light phases of light fluctuations and describe their role in growth under rapid light fluctuations. We further reveal an activation of NPQ during the dark phases of all high light/dark cycles and show that this phenomenon arises from state transition. Finally, we show that LHCSRs and state transition synergistically cooperate to enable NPQ response during light fluctuations. These results highlight the dynamic functioning of photoprotection under light fluctuations and open a new way to systematically characterize the photosynthetic response to an ever-changing light environment.
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Affiliation(s)
- Collin J. Steen
- Department of ChemistryUniversity of CaliforniaBerkeleyCaliforniaUSA
- Molecular Biophysics and Integrated Bioimaging Division Lawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
- Kavli Energy Nanoscience InstituteBerkeleyCaliforniaUSA
| | - Adrien Burlacot
- Howard Hughes Medical InstituteUniversity of CaliforniaBerkeleyCaliforniaUSA
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCaliforniaUSA
- Department of Plant BiologyCarnegie Institution for ScienceStanfordCaliforniaUSA
| | - Audrey H. Short
- Molecular Biophysics and Integrated Bioimaging Division Lawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
- Kavli Energy Nanoscience InstituteBerkeleyCaliforniaUSA
- Graduate Group in BiophysicsUniversity of CaliforniaBerkeleyCaliforniaUSA
| | - Krishna K. Niyogi
- Molecular Biophysics and Integrated Bioimaging Division Lawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
- Howard Hughes Medical InstituteUniversity of CaliforniaBerkeleyCaliforniaUSA
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCaliforniaUSA
| | - Graham R. Fleming
- Department of ChemistryUniversity of CaliforniaBerkeleyCaliforniaUSA
- Molecular Biophysics and Integrated Bioimaging Division Lawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
- Kavli Energy Nanoscience InstituteBerkeleyCaliforniaUSA
- Graduate Group in BiophysicsUniversity of CaliforniaBerkeleyCaliforniaUSA
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7
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Selection-enriched genomic loci (SEGL) reveals genetic loci for environmental adaptation and photosynthetic productivity in Chlamydomonas reinhardtii. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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8
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Hupp J, McCoy JI, Millgan AJ, Peers G. Simultaneously measuring carbon uptake capacity and chlorophyll a fluorescence dynamics in algae. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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9
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Microalgae with a truncated light-harvesting antenna to maximize photosynthetic efficiency and biomass productivity: Recent advances and current challenges. Process Biochem 2021. [DOI: 10.1016/j.procbio.2021.03.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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10
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Barera S, Dall'Osto L, Bassi R. Effect of lhcsr gene dosage on oxidative stress and light use efficiency by Chlamydomonas reinhardtii cultures. J Biotechnol 2021; 328:12-22. [PMID: 33434600 DOI: 10.1016/j.jbiotec.2020.12.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/27/2020] [Accepted: 12/31/2020] [Indexed: 10/22/2022]
Abstract
Unicellular green algae, a promising source for renewable biofuels, produce lipid-rich biomass from light and CO2. Productivity in photo-bioreactors is affected by inhomogeneous light distribution from high cell pigment causing heat dissipation of light energy absorbed in excess and shading of the deep layers. Contrasting reports have been published on the relation between photoprotective energy dissipation and productivity. Here, we have re-investigated the relation between energy quenching (qE) activity, photodamage and light use efficiency by comparing WT and two Chlamydomonas reinhardtii strains differing for their complement in LHCSR proteins, which catalyse dissipation of excitation energy in excess (qE). Strains were analysed for ROS production, protein composition, rate of photodamage and productivity assessed under wide light and CO2 conditions. The strain lacking LHCSR1 and knocked down in LHCSR3, thus depleted in qE, produced O2 at significantly higher rate under high light, accompanied by enhanced singlet oxygen release and PSII photodamage. However, biomass productivity of WT was delayed in respect for mutant strains under intermittent light conditions only, implying that PSII activity was not the limiting factor under excess light. Contrary to previous proposals, domestication of Chlamydomonas for carbon assimilation rate in photo-bioreactors by down-regulation of photoprotective energy dissipation was ineffective in increasing algal biomass productivity.
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Affiliation(s)
- Simone Barera
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134, Verona, Italy.
| | - Luca Dall'Osto
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134, Verona, Italy.
| | - Roberto Bassi
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134, Verona, Italy.
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11
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Meagher E, Rangsrikitphoti P, Faridi B, Zamzam G, Durnford DG. Photoacclimation to high-light stress in Chlamydomonas reinhardtii during conditional senescence relies on generating pH-dependent, high-quenching centres. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 158:136-145. [PMID: 33307425 DOI: 10.1016/j.plaphy.2020.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
Microalgae can respond to long-term increases in light intensity by altering the concentration of photosynthetic complexes. Under active growth, the ability of Chlamydomonas reinhardtii to acclimate to excess light is dependent on cell division to reduce the concentration of photosynthetic complexes. But, in batch culture, cells eventually reach stationary phase where their ability to divide is limited; this should impact their capacity to undergo photoacclimation. Our goal is to dissect excess-light responses as cells approach stationary phase and to determine how the strategies of photoacclimation differ compared to cells in the exponential-growth phase. In this study, cultures exited exponential growth and transitioned into a declining growth phase (DGP), where cells continued a slow rate of growth for the next seven days in both low (LL) and high-light (HL). During this period, both cultures experience a conditional senescence-related decline in chlorophyll levels. Under HL, however, the senescing cultures have a rapid decline in PSII reaction centres, maintain a stable concentration of LHCII antenna, rapidly increase LHCSR levels, and have a sustained increase in Fo/Fm. Collectively this implies that the remaining antenna act as pH-dependent, quenching centres, presumably to protect the senescing chloroplast against HL. We discovered that acclimating to HL post-exponential phase involves active degradation that is intertwined with the normal senescence process that allowed for a limited rate of cell division.
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Affiliation(s)
- Emily Meagher
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | | | - Babar Faridi
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | - Ghaith Zamzam
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | - Dion G Durnford
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada.
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12
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Perozeni F, Beghini G, Cazzaniga S, Ballottari M. Chlamydomonas reinhardtii LHCSR1 and LHCSR3 proteins involved in photoprotective non-photochemical quenching have different quenching efficiency and different carotenoid affinity. Sci Rep 2020; 10:21957. [PMID: 33319824 PMCID: PMC7738518 DOI: 10.1038/s41598-020-78985-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 12/02/2020] [Indexed: 11/09/2022] Open
Abstract
Microalgae are unicellular photosynthetic organisms considered as potential alternative sources for biomass, biofuels or high value products. However, their limited biomass productivity represents a bottleneck that needs to be overcome to meet the applicative potential of these organisms. One of the domestication targets for improving their productivity is the proper balance between photoprotection and light conversion for carbon fixation. In the model organism for green algae, Chlamydomonas reinhardtii, a photoprotective mechanism inducing thermal dissipation of absorbed light energy, called Non-photochemical quenching (NPQ), is activated even at relatively low irradiances, resulting in reduced photosynthetic efficiency. Two pigment binding proteins, LHCSR1 and LHCSR3, were previously reported as the main actors during NPQ induction in C. reinhardtii. While previous work characterized in detail the functional properties of LHCSR3, few information is available for the LHCSR1 subunit. Here, we investigated in vitro the functional properties of LHCSR1 and LHCSR3 subunits: despite high sequence identity, the latter resulted as a stronger quencher compared to the former, explaining its predominant role observed in vivo. Pigment analysis, deconvolution of absorption spectra and structural models of LHCSR1 and LHCR3 suggest that different quenching efficiency is related to a different occupancy of L2 carotenoid binding site.
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Affiliation(s)
- Federico Perozeni
- Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134, Verona, Italy
| | - Giorgia Beghini
- Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134, Verona, Italy
| | - Stefano Cazzaniga
- Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134, Verona, Italy
| | - Matteo Ballottari
- Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134, Verona, Italy.
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13
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Roach T. LHCSR3-Type NPQ Prevents Photoinhibition and Slowed Growth under Fluctuating Light in Chlamydomonas reinhardtii. PLANTS 2020; 9:plants9111604. [PMID: 33218177 PMCID: PMC7698959 DOI: 10.3390/plants9111604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/05/2020] [Accepted: 11/16/2020] [Indexed: 01/14/2023]
Abstract
Natural light intensities can rise several orders of magnitude over subsecond time spans, posing a major challenge for photosynthesis. Fluctuating light tolerance in the green alga Chlamydomonas reinhardtii requires alternative electron pathways, but the role of nonphotochemical quenching (NPQ) is not known. Here, fluctuating light (10 min actinic light followed by 10 min darkness) led to significant increase in NPQ/qE-related proteins, LHCSR1 and LHCSR3, relative to constant light of the same subsaturating or saturating intensity. Elevated levels of LHCSR1/3 increased the ability of cells to safely dissipate excess light energy to heat (i.e., qE-type NPQ) during dark to light transition, as measured with chlorophyll fluorescence. The low qE phenotype of the npq4 mutant, which is unable to produce LHCSR3, was abolished under fluctuating light, showing that LHCSR1 alone enables very high levels of qE. Photosystem (PS) levels were also affected by light treatments; constant light led to lower PsbA levels and Fv/Fm values, while fluctuating light led to lower PsaA and maximum P700+ levels, indicating that constant and fluctuating light induced PSII and PSI photoinhibition, respectively. Under fluctuating light, npq4 suffered more PSI photoinhibition and significantly slower growth rates than parental wild type, whereas npq1 and npq2 mutants affected in xanthophyll carotenoid compositions had identical growth under fluctuating and constant light. Overall, LHCSR3 rather than total qE capacity or zeaxanthin is shown to be important in C. reinhardtii in tolerating fluctuating light, potentially via preventing PSI photoinhibition.
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Affiliation(s)
- Thomas Roach
- Department of Botany and Centre for Molecular Biosciences Innsbruck, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria
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14
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Ware MA, Hunstiger D, Cantrell M, Peers G. A Chlorophyte Alga Utilizes Alternative Electron Transport for Primary Photoprotection. PLANT PHYSIOLOGY 2020; 183:1735-1748. [PMID: 32457091 PMCID: PMC7401117 DOI: 10.1104/pp.20.00373] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 04/28/2020] [Indexed: 05/28/2023]
Abstract
The green alga Desmodesmus armatus is an emerging biofuel platform that produces high amounts of lipids and biomass in mass culture. We observed D. armatus in light-limiting, excess-light, and sinusoidal-light environments to investigate its photoacclimation behaviors and the mechanisms by which it dissipates excess energy. Chlorophyll a/b ratios and the functional absorption cross section of PSII suggested a constitutively small light-harvesting antenna size relative to other green algae. In situ and ex situ measurements of photo-physiology revealed that nonphotochemical quenching is not a significant contributor to photoprotection; however, cells do not suffer substantial photoinhibition despite its near absence. We performed membrane inlet mass spectrometry analysis to show that D. armatus has a very high capacity for alternative electron transport (AET) measured as light-dependent oxygen consumption. Up to 90% of electrons generated at PSII can be dissipated by AET in a water-water cycle during growth in rapidly fluctuating light environments, like those found in industrial-scale photobioreactors. This work highlights the diversity of photoprotective mechanisms present in algal systems, indicating that nonphotochemical quenching is not necessarily required for effective photoprotection in some algae, and suggests that engineering AET may be an attractive target for increasing the biomass productivity of some strains.
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Affiliation(s)
- Maxwell A Ware
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Darcy Hunstiger
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Michael Cantrell
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Graham Peers
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523
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Roach T, Na CS, Stöggl W, Krieger-Liszkay A. The non-photochemical quenching protein LHCSR3 prevents oxygen-dependent photoinhibition in Chlamydomonas reinhardtii. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:2650-2660. [PMID: 31943079 PMCID: PMC7210768 DOI: 10.1093/jxb/eraa022] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 01/13/2020] [Indexed: 05/18/2023]
Abstract
Non-photochemical quenching (NPQ) helps dissipate surplus light energy, preventing formation of reactive oxygen species (ROS). In Chlamydomonas reinhardtii, the thylakoid membrane protein LHCSR3 is involved in pH-dependent (qE-type) NPQ, lacking in the npq4 mutant. Preventing PSII repair revealed that npq4 lost PSII activity faster than the wild type (WT) in elevated O2, while no difference between strains was observed in O2-depleted conditions. Low Fv/Fm values remained 1.5 h after moving cells out of high light, and this qH-type quenching was independent of LHCSR3 and not accompanied by losses of maximum PSII activity. Culturing cells in historic O2 atmospheres (30-35%) increased the qE of cells, due to increased LHCSR1 and PsbS levels, and LHCSR3 in the WT, showing that atmospheric O2 tensions regulate qE capacity. Colony growth of npq4 was severely restricted at elevated O2, and npq4 accumulated more reactive electrophile species (RES) than the WT, which could damage PSI. Levels of PsaA (PSI) were lower in npq4 grown at 35% O2, while PsbA (PSII) levels remained stable. We conclude that even at high O2 concentrations, the PSII repair cycle is sufficient to maintain net levels of PSII. However, LHCSR3 has an important function in protecting PSI against O2-mediated damage, such as via RES.
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Affiliation(s)
- Thomas Roach
- Department of Botany and Centre for Molecular Biology Innsbruck, Leopold-Franzens-Universität-Innsbruck, Sternwartestraße 15, Innsbruck, Austria
- Correspondence:
| | - Chae Sun Na
- Department of Botany and Centre for Molecular Biology Innsbruck, Leopold-Franzens-Universität-Innsbruck, Sternwartestraße 15, Innsbruck, Austria
- Seed Conservation Research Division, Department of Seed Vault, Baekdudaegan National Arboretum, Munsu-ro, Chunyang-myeon, Bonghwa-gun, Gyeongsangbuk-do, Republic of Korea
| | - Wolfgang Stöggl
- Department of Botany and Centre for Molecular Biology Innsbruck, Leopold-Franzens-Universität-Innsbruck, Sternwartestraße 15, Innsbruck, Austria
| | - Anja Krieger-Liszkay
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
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16
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Benedetti M, Vecchi V, Barera S, Dall’Osto L. Biomass from microalgae: the potential of domestication towards sustainable biofactories. Microb Cell Fact 2018; 17:173. [PMID: 30414618 PMCID: PMC6230293 DOI: 10.1186/s12934-018-1019-3] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 10/31/2018] [Indexed: 12/22/2022] Open
Abstract
Interest in bulk biomass from microalgae, for the extraction of high-value nutraceuticals, bio-products, animal feed and as a source of renewable fuels, is high. Advantages of microalgal vs. plant biomass production include higher yield, use of non-arable land, recovery of nutrients from wastewater, efficient carbon capture and faster development of new domesticated strains. Moreover, adaptation to a wide range of environmental conditions evolved a great genetic diversity within this polyphyletic group, making microalgae a rich source of interesting and useful metabolites. Microalgae have the potential to satisfy many global demands; however, realization of this potential requires a decrease of the current production costs. Average productivity of the most common industrial strains is far lower than maximal theoretical estimations, suggesting that identification of factors limiting biomass yield and removing bottlenecks are pivotal in domestication strategies aimed to make algal-derived bio-products profitable on the industrial scale. In particular, the light-to-biomass conversion efficiency represents a major constraint to finally fill the gap between theoretical and industrial productivity. In this respect, recent results suggest that significant yield enhancement is feasible. Full realization of this potential requires further advances in cultivation techniques, together with genetic manipulation of both algal physiology and metabolic networks, to maximize the efficiency with which solar energy is converted into biomass and bio-products. In this review, we draft the molecular events of photosynthesis which regulate the conversion of light into biomass, and discuss how these can be targeted to enhance productivity through mutagenesis, strain selection or genetic engineering. We outline major successes reached, and promising strategies to achieving significant contributions to future microalgae-based biotechnology.
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Affiliation(s)
- Manuel Benedetti
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Valeria Vecchi
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Simone Barera
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Luca Dall’Osto
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134 Verona, Italy
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LHCSR Expression under HSP70/RBCS2 Promoter as a Strategy to Increase Productivity in Microalgae. Int J Mol Sci 2018; 19:ijms19010155. [PMID: 29303960 PMCID: PMC5796104 DOI: 10.3390/ijms19010155] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 12/24/2017] [Accepted: 12/31/2017] [Indexed: 11/17/2022] Open
Abstract
Microalgae are unicellular photosynthetic organisms considered as potential alternative sources for biomass, biofuels or high value products. However, limited biomass productivity is commonly experienced in their cultivating system despite their high potential. One of the reasons for this limitation is the high thermal dissipation of the light absorbed by the outer layers of the cultures exposed to high light caused by the activation of a photoprotective mechanism called non-photochemical quenching (NPQ). In the model organism for green algae Chlamydomonas reinhardtii, NPQ is triggered by pigment binding proteins called light-harvesting-complexes-stress-related (LHCSRs), which are over-accumulated in high light. It was recently reported that biomass productivity can be increased both in microalgae and higher plants by properly tuning NPQ induction. In this work increased light use efficiency is reported by introducing in C. reinhardtii a LHCSR3 gene under the control of Heat Shock Protein 70/RUBISCO small chain 2 promoter in a npq4 lhcsr1 background, a mutant strain knockout for all LHCSR genes. This complementation strategy leads to a low expression of LHCSR3, causing a strong reduction of NPQ induction but is still capable of protecting from photodamage at high irradiance, resulting in an improved photosynthetic efficiency and higher biomass accumulation.
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