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Krishnan A, Cano M, Karns DA, Burch TA, Likhogrud M, Aqui M, Bailey S, Verruto J, Lambert W, Kuzminov F, Naghipor M, Wang Y, Ebmeier CC, Weissman JC, Posewitz MC. Simultaneous CAS9 editing of cp SRP43, LHCA6, and LHCA7 in Picochlorum celeri lowers chlorophyll levels and improves biomass productivity. PLANT DIRECT 2023; 7:e530. [PMID: 37711644 PMCID: PMC10497401 DOI: 10.1002/pld3.530] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/03/2023] [Accepted: 08/17/2023] [Indexed: 09/16/2023]
Abstract
High cellular pigment levels in dense microalgal cultures contribute to excess light absorption. To improve photosynthetic yields in the marine microalga Picochlorum celeri, CAS9 gene editing was used to target the molecular chaperone cpSRP43. Depigmented strains (>50% lower chlorophyll) were generated, with proteomics showing attenuated levels of most light harvesting complex (LHC) proteins. Gene editing generated two types of cpSRP43 transformants with distinct lower pigment phenotypes: (i) a transformant (Δsrp43) with both cpSRP43 diploid alleles modified to encode non-functional polypeptides and (ii) a transformant (STR30309) with a 3 nt in-frame insertion in one allele at the CAS9 cut site (non-functional second allele), leading to expression of a modified cpSRP43. STR30309 has more chlorophyll than Δsrp43 but substantially less than wild type. To further decrease light absorption by photosystem I in STR30309, CAS9 editing was used to stack in disruptions of both LHCA6 and LHCA7 to generate STR30843, which has higher (5-24%) productivities relative to wild type in solar-simulating bioreactors. Maximal productivities required frequent partial harvests throughout the day. For STR30843, exemplary diel bioreactor yields of ~50 g m-2 day-1 were attained. Our results demonstrate diel productivity gains in P. celeri by lowering pigment levels.
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Affiliation(s)
- Anagha Krishnan
- Department of ChemistryColorado School of MinesGoldenColoradoUSA
| | - Melissa Cano
- Department of ChemistryColorado School of MinesGoldenColoradoUSA
| | - Devin A. Karns
- Department of ChemistryColorado School of MinesGoldenColoradoUSA
| | - Tyson A. Burch
- Department of ChemistryColorado School of MinesGoldenColoradoUSA
| | - Maria Likhogrud
- ExxonMobil Technology and Engineering CompanyAnnandaleNew JerseyUSA
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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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Joliot P, Sellés J, Wollman FA, Verméglio A. High efficient cyclic electron flow and functional supercomplexes in Chlamydomonas cells. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148909. [PMID: 35952798 DOI: 10.1016/j.bbabio.2022.148909] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 08/02/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
A very high rate for cyclic electron flow (CEF) around PSI (~180 s-1 or 210 s-1 in minimum medium or in the presence of a carbon source respectively) is measured in the presence of methyl viologen (MV) in intact cells of Chlamydomonas reinhardtii under anaerobic conditions. The observation of an efficient CEF in the presence of methyl viologen is in agreement with the previous results reports of Asada et al. in broken chloroplasts (Plant Cell Physiol. 31(4) (1990) 557-564). From the analysis of the P700 and PC absorbance changes, we propose that a confinement between 2 PC molecules, 1 PSI and 1 cytb6f corresponding to a functional supercomplex is responsible for these high rates of CEF. Supercomplex formation is also observed in the absence of methyl viologen, but with lower maximal CEF rate (about 100 s-1) suggesting that this compound facilitates the mediation of electron transfer from PSI acceptors to the stromal side of cytb6f. Further analysis of CEF in mutants of Chlamydomonas defective in state transitions shows the requirement of a kinase-driven transition to state 2 to establish this functional supercomplex configuration. However, a movement of the LHCII antennae is not involved in this process. We discuss the possible involvement of auxiliary proteins, among which is a small cytb6f-associated polypeptide, the PETO protein, which is one of the targets of the STT7 kinase.
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Affiliation(s)
- Pierre Joliot
- Laboratoire de Biologie du Chloroplaste et Perception de la Lumière Chez les Microalgues, Institut de Biologie Physico-Chimique, CNRS UMR 7141, Sorbonne Université, Paris, France.
| | - Julien Sellés
- Laboratoire de Biologie du Chloroplaste et Perception de la Lumière Chez les Microalgues, Institut de Biologie Physico-Chimique, CNRS UMR 7141, Sorbonne Université, Paris, France.
| | - Françis-André Wollman
- Laboratoire de Biologie du Chloroplaste et Perception de la Lumière Chez les Microalgues, Institut de Biologie Physico-Chimique, CNRS UMR 7141, Sorbonne Université, Paris, France
| | - André Verméglio
- Laboratoire de Biologie du Chloroplaste et Perception de la Lumière Chez les Microalgues, Institut de Biologie Physico-Chimique, CNRS UMR 7141, Sorbonne Université, Paris, France
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Nawrocki WJ, Liu X, Raber B, Hu C, de Vitry C, Bennett DIG, Croce R. Molecular origins of induction and loss of photoinhibition-related energy dissipation q I. SCIENCE ADVANCES 2021; 7:eabj0055. [PMID: 34936440 PMCID: PMC8694598 DOI: 10.1126/sciadv.abj0055] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Photosynthesis fuels life on Earth using sunlight as energy source. However, light has a simultaneous detrimental effect on the enzyme triggering photosynthesis and producing oxygen, photosystem II (PSII). Photoinhibition, the light-dependent decrease of PSII activity, results in a major limitation to aquatic and land photosynthesis and occurs upon all environmental stress conditions. In this work, we investigated the molecular origins of photoinhibition focusing on the paradoxical energy dissipation process of unknown nature coinciding with PSII damage. Integrating spectroscopic, biochemical, and computational approaches, we demonstrate that the site of this quenching process is the PSII reaction center. We propose that the formation of quenching and the closure of PSII stem from the same event. We lastly reveal the heterogeneity of PSII upon photoinhibition using structure-function modeling of excitation energy transfer. This work unravels the functional details of the damage-induced energy dissipation at the heart of photosynthesis.
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Affiliation(s)
- Wojciech J. Nawrocki
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands
- LaserLaB Amsterdam, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands
- Corresponding author. (W.J.N.); (R.C.)
| | - Xin Liu
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands
- LaserLaB Amsterdam, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands
| | - Bailey Raber
- Department of Chemistry, Southern Methodist University, P.O. Box 750314, Dallas, TX, USA
| | - Chen Hu
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands
- LaserLaB Amsterdam, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands
| | - Catherine de Vitry
- Institut de Biologie Physico-Chimique, UMR 7141, CNRS-Sorbonne Université, 75005 Paris, France
| | - Doran I. G. Bennett
- Department of Chemistry, Southern Methodist University, P.O. Box 750314, Dallas, TX, USA
| | - Roberta Croce
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands
- LaserLaB Amsterdam, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands
- Corresponding author. (W.J.N.); (R.C.)
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