1
|
Nigishi M, Shimakawa G, Yamagishi K, Amano R, Ito S, Tsuji Y, Nagasato C, Matsuda Y. Low-CO2-inducible bestrophins outside the pyrenoid sustain high photosynthetic efficacy in diatoms. PLANT PHYSIOLOGY 2024; 195:1432-1445. [PMID: 38478576 PMCID: PMC11142338 DOI: 10.1093/plphys/kiae137] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 01/18/2024] [Indexed: 06/02/2024]
Abstract
Anion transporters sustain a variety of physiological states in cells. Bestrophins (BSTs) belong to a Cl- and/or HCO3- transporter family conserved in bacteria, animals, algae, and plants. Recently, putative BSTs were found in the green alga Chlamydomonas reinhardtii, where they are upregulated under low CO2 (LC) conditions and play an essential role in the CO2-concentrating mechanism (CCM). The putative BST orthologs are also conserved in diatoms, secondary endosymbiotic algae harboring red-type plastids, but their physiological functions are unknown. Here, we characterized the subcellular localization and expression profile of BSTs in the marine diatoms Phaeodactylum tricornutum (PtBST1 to 4) and Thalassiosira pseudonana (TpBST1 and 2). PtBST1, PtBST2, and PtBST4 were localized at the stroma thylakoid membrane outside of the pyrenoid, and PtBST3 was localized in the pyrenoid. Contrarily, TpBST1 and TpBST2 were both localized in the pyrenoid. These BST proteins accumulated in cells grown in LC but not in 1% CO2 (high CO2 [HC]). To assess the physiological functions, we generated knockout mutants for the PtBST1 gene by genome editing. The lack of PtBST1 decreased photosynthetic affinity for dissolved inorganic carbon to the level comparable with the HC-grown wild type. Furthermore, non-photochemical quenching in LC-grown cells was 1.5 to 2.0 times higher in the mutants than in the wild type. These data suggest that HCO3- transport at the stroma thylakoid membranes by PtBST1 is a critical part of the CO2-evolving machinery of the pyrenoid in the fully induced CCM and that PtBST1 may modulate photoprotection under CO2-limited environments in P. tricornutum.
Collapse
Affiliation(s)
- Minori Nigishi
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo 669-1330, Japan
| | - Ginga Shimakawa
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo 669-1330, Japan
| | - Kansei Yamagishi
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo 669-1330, Japan
| | - Ryosuke Amano
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo 669-1330, Japan
| | - Shun Ito
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo 669-1330, Japan
| | - Yoshinori Tsuji
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo 669-1330, Japan
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Chikako Nagasato
- Field Science Center for Northern Biosphere, Muroran Marine Station, Hokkaido University, Muroran 051-0013, Japan
| | - Yusuke Matsuda
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo 669-1330, Japan
| |
Collapse
|
2
|
Kamakura S, Bilcke G, Sato S. Transcriptional responses to salinity-induced changes in cell wall morphology of the euryhaline diatom Pleurosira laevis. JOURNAL OF PHYCOLOGY 2024; 60:308-326. [PMID: 38446079 DOI: 10.1111/jpy.13437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 01/23/2024] [Accepted: 02/05/2024] [Indexed: 03/07/2024]
Abstract
Diatoms are unicellular algae with morphologically diverse silica cell walls, which are called frustules. The mechanism of frustule morphogenesis has attracted attention in biology and nanomaterials engineering. However, the genetic regulation of the morphology remains unclear. We therefore used transcriptome sequencing to search for genes involved in frustule morphology in the centric diatom Pleurosira laevis, which exhibits morphological plasticity between flat and domed valve faces in salinity 2 and 7, respectively. We observed differential expression of transposable elements (TEs) and transporters, likely due to osmotic response. Up-regulation of mechanosensitive ion channels and down-regulation of Ca2+-ATPases in cells with flat valves suggested that cytosolic Ca2+ levels were changed between the morphologies. Calcium signaling could be a mechanism for detecting osmotic pressure changes and triggering morphological shifts. We also observed an up-regulation of ARPC1 and annexin, involved in the regulation of actin filament dynamics known to affect frustule morphology, as well as the up-regulation of genes encoding frustule-related proteins such as BacSETs and frustulin. Taken together, we propose a model in which salinity-induced morphogenetic changes are driven by upstream responses, such as the regulation of cytosolic Ca2+ levels, and downstream responses, such as Ca2+-dependent regulation of actin dynamics and frustule-related proteins. This study highlights the sensitivity of euryhaline diatoms to environmental salinity and the role of active cellular processes in controlling gross valve morphology under different osmotic pressures.
Collapse
Affiliation(s)
- Shiho Kamakura
- Graduate School of Bioscience and Biotechnology, Fukui Prefectural University, Obama, Fukui, Japan
| | - Gust Bilcke
- VIB Center for Plant Systems Biology, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium
| | - Shinya Sato
- Faculty of Marine Science and Technology, Fukui Prefectural University, Obama, Fukui, Japan
| |
Collapse
|
3
|
Shimakawa G, Matsuda Y. Extra O 2 evolution reveals an O 2-independent alternative electron sink in photosynthesis of marine diatoms. PHOTOSYNTHESIS RESEARCH 2024; 159:61-68. [PMID: 38316719 DOI: 10.1007/s11120-023-01073-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 12/27/2023] [Indexed: 02/07/2024]
Abstract
Following the principle of oxygenic photosynthesis, electron transport in the thylakoid membranes (i.e., light reaction) generates ATP and NADPH from light energy, which is subsequently utilized for CO2 fixation in the Calvin-Benson-Bassham cycle (i.e., dark reaction). However, light and dark reactions could discord when an alternative electron flow occurs with a rate comparable to the linear electron flow. Here, we quantitatively monitored O2 and total dissolved inorganic carbon (DIC) during photosynthesis in the pennate diatom Phaeodactylum tricornutum, and found that evolved O2 was larger than the consumption of DIC, which was consistent with 14CO2 measurements in literature. In our measurements, the stoichiometry of O2 evolution to DIC consumption was always around 1.5 during photosynthesis at different DIC concentrations. The same stoichiometry was observed in the cells grown under different CO2 concentrations and nitrogen sources except for the nitrogen-starved cells showing O2 evolution 2.5 times larger than DIC consumption. An inhibitor to nitrogen assimilation did not affect the extra O2 evolution. Further, the same physiological phenomenon was observed in the centric diatom Thalassiosira pseudonana. Based on the present dataset, we propose that the marine diatoms possess the metabolic pathway(s) functioning as the O2-independent electron sink under steady state photosynthesis that reaches nearly half of electron flux of the Calvin-Benson-Bassham cycle.
Collapse
Affiliation(s)
- Ginga Shimakawa
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo, 669-1330, Japan.
| | - Yusuke Matsuda
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo, 669-1330, Japan
| |
Collapse
|
4
|
Shimakawa G, Yashiro E, Matsuda Y. Mapping of subcellular local pH in the marine diatom Phaeodactylum tricornutum. PHYSIOLOGIA PLANTARUM 2023; 175:e14086. [PMID: 38148208 DOI: 10.1111/ppl.14086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/30/2023] [Accepted: 10/30/2023] [Indexed: 12/28/2023]
Abstract
Diatoms are one of the most important phytoplankton on Earth. They comprise at least ten thousand species and contribute to up to 20% of the global primary production. Because of serial endosymbiotic events and horizontal gene transfers, diatoms have developed a "secondary plastid" bounded by four membranes containing a large phase-separated compartment, termed the pyrenoid. However, the physiological significance of this unique chloroplast morphology is poorly understood. Characterization of fundamental physiological parameters such as local pH in various subcellular compartments should facilitate a greater understanding of the physiological roles of the unique structure of the secondary plastid. A promising method to estimate local pH is the in situ expression of the pH-sensitive green fluorescent protein. Here, we first developed the molecular tool for the mapping of in situ local pH in the diatom Phaeodactylum tricornutum by heterologously expressing pHluorin2 in the cytosol, periplastidal compartment (PPC; the space in between two sets of outer and inner chloroplast envelopes), chloroplast stroma, and the pyrenoid matrix. Our data suggested that PPC and the pyrenoid matrix are more acidic than the adjacent areas, the cytosol and the chloroplast stroma. Finally, absolute pH values at each compartment were estimated from the ratiometric fluorescence of a recombinant pHluorin2 protein, giving pH values of approximately 7.9, 6.8, 8.0, and 7.5 respectively, for the cytosol, PPC, stroma, and pyrenoid of the P. tricornutum cells, indicating the occurrence of pH gradients and the associated electrochemical potentials at their boundary.
Collapse
Affiliation(s)
- Ginga Shimakawa
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Emi Yashiro
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Yusuke Matsuda
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo, Japan
| |
Collapse
|
5
|
Burlacot A, Peltier G. Energy crosstalk between photosynthesis and the algal CO 2-concentrating mechanisms. TRENDS IN PLANT SCIENCE 2023; 28:795-807. [PMID: 37087359 DOI: 10.1016/j.tplants.2023.03.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 03/16/2023] [Accepted: 03/18/2023] [Indexed: 05/03/2023]
Abstract
Microalgal photosynthesis is responsible for nearly half of the CO2 annually captured by Earth's ecosystems. In aquatic environments where the CO2 availability is low, the CO2-fixing efficiency of microalgae greatly relies on mechanisms - called CO2-concentrating mechanisms (CCMs) - for concentrating CO2 at the catalytic site of the CO2-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). While the transport of inorganic carbon (Ci) across membrane bilayers against a concentration gradient consumes part of the chemical energy generated by photosynthesis, the bioenergetics and cellular mechanisms involved are only beginning to be elucidated. Here, we review the current knowledge relating to the energy requirement of CCMs in the light of recent advances in photosynthesis regulatory mechanisms and the spatial organization of CCM components.
Collapse
Affiliation(s)
- Adrien Burlacot
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA.
| | - Gilles Peltier
- Aix-Marseille Université, CEA, CNRS, Institut de Biosciences et Biotechnologies Aix-Marseille, CEA Cadarache, 13108 Saint-Paul-lez-Durance, France.
| |
Collapse
|
6
|
Yee DP, Samo TJ, Abbriano RM, Shimasaki B, Vernet M, Mayali X, Weber PK, Mitchell BG, Hildebrand M, Decelle J, Tresguerres M. The V-type ATPase enhances photosynthesis in marine phytoplankton and further links phagocytosis to symbiogenesis. Curr Biol 2023; 33:2541-2547.e5. [PMID: 37263270 PMCID: PMC10326425 DOI: 10.1016/j.cub.2023.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 03/20/2023] [Accepted: 05/09/2023] [Indexed: 06/03/2023]
Abstract
Diatoms, dinoflagellates, and coccolithophores are dominant groups of marine eukaryotic phytoplankton that are collectively responsible for the majority of primary production in the ocean.1 These phytoplankton contain additional intracellular membranes around their chloroplasts, which are derived from ancestral engulfment of red microalgae by unicellular heterotrophic eukaryotes that led to secondary and tertiary endosymbiosis.2 However, the selectable evolutionary advantage of these membranes and the physiological significance for extant phytoplankton remain poorly understood. Since intracellular digestive vacuoles are ubiquitously acidified by V-type H+-ATPase (VHA),3 proton pumps were proposed to acidify the microenvironment around secondary chloroplasts to promote the dehydration of dissolved inorganic carbon (DIC) into CO2, thus enhancing photosynthesis.4,5 We report that VHA is localized around the chloroplasts of centric diatoms and that VHA significantly contributes to their photosynthesis across a wide range of oceanic irradiances. Similar results in a pennate diatom, dinoflagellate, and coccolithophore, but not green or red microalgae, imply the co-option of phagocytic VHA activity into a carbon-concentrating mechanism (CCM) is common to secondary endosymbiotic phytoplankton. Furthermore, analogous mechanisms in extant photosymbiotic marine invertebrates6,7,8 provide functional evidence for an adaptive advantage throughout the transition from endosymbiosis to symbiogenesis. Based on the contribution of diatoms to ocean biogeochemical cycles, VHA-mediated enhancement of photosynthesis contributes at least 3.5 Gtons of fixed carbon per year (or 7% of primary production in the ocean), providing an example of a symbiosis-derived evolutionary innovation with global environmental implications.
Collapse
Affiliation(s)
- Daniel P Yee
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Cell and Plant Physiology Laboratory, University of Grenoble Alpes, CNRS, CEA, INRAE, and IRIG, 17 Avenue des Martyrs, Grenoble 38054, Auvergne-Rhone-Alpes, France.
| | - Ty J Samo
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Raffaela M Abbriano
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Bethany Shimasaki
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Maria Vernet
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Xavier Mayali
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Peter K Weber
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - B Greg Mitchell
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Mark Hildebrand
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Johan Decelle
- Cell and Plant Physiology Laboratory, University of Grenoble Alpes, CNRS, CEA, INRAE, and IRIG, 17 Avenue des Martyrs, Grenoble 38054, Auvergne-Rhone-Alpes, France
| | - Martin Tresguerres
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
| |
Collapse
|
7
|
Li M, Young JN. Temperature sensitivity of carbon concentrating mechanisms in the diatom Phaeodactylum tricornutum. PHOTOSYNTHESIS RESEARCH 2023; 156:205-215. [PMID: 36881356 PMCID: PMC10154264 DOI: 10.1007/s11120-023-01004-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 02/10/2023] [Indexed: 05/03/2023]
Abstract
Marine diatoms are key primary producers across diverse habitats in the global ocean. Diatoms rely on a biophysical carbon concentrating mechanism (CCM) to supply high concentrations of CO2 around their carboxylating enzyme, RuBisCO. The necessity and energetic cost of the CCM are likely to be highly sensitive to temperature, as temperature impacts CO2 concentration, diffusivity, and the kinetics of CCM components. Here, we used membrane inlet mass spectrometry (MIMS) and modeling to capture temperature regulation of the CCM in the diatom Phaeodactylum tricornutum (Pt). We found that enhanced carbon fixation rates by Pt at elevated temperatures were accompanied by increased CCM activity capable of maintaining RuBisCO close to CO2 saturation but that the mechanism varied. At 10 and 18 °C, diffusion of CO2 into the cell, driven by Pt's 'chloroplast pump' was the major inorganic carbon source. However, at 18 °C, upregulation of the chloroplast pump enhanced (while retaining the proportion of) both diffusive CO2 and active HCO3- uptake into the cytosol, and significantly increased chloroplast HCO3- concentrations. In contrast, at 25 °C, compared to 18 °C, the chloroplast pump had only a slight increase in activity. While diffusive uptake of CO2 into the cell remained constant, active HCO3- uptake across the cell membrane increased resulting in Pt depending equally on both CO2 and HCO3- as inorganic carbon sources. Despite changes in the CCM, the overall rate of active carbon transport remained double that of carbon fixation across all temperatures tested. The implication of the energetic cost of the Pt CCM in response to increasing temperatures was discussed.
Collapse
Affiliation(s)
- Meng Li
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Jodi N Young
- School of Oceanography, University of Washington, Seattle, WA, USA.
| |
Collapse
|
8
|
Nawaly H, Tanaka A, Toyoshima Y, Tsuji Y, Matsuda Y. Localization and characterization θ carbonic anhydrases in Thalassiosira pseudonana. PHOTOSYNTHESIS RESEARCH 2023; 156:217-229. [PMID: 36862281 DOI: 10.1007/s11120-023-01007-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 02/12/2023] [Indexed: 05/03/2023]
Abstract
Carbonic anhydrase (CA) is a crucial component for the operation of CO2-concentrating mechanisms (CCMs) in the majority of aquatic photoautotrophs that maintain the global primary production. In the genome of the centric marine diatom, Thalassiosira pseudonana, there are four putative gene sequences that encode θ-type CA, which was a type of CA recently identified in marine diatoms and green algae. In the present study, specific subcellular locations of four θCAs, TpθCA1, TpθCA2, TpθCA3, and TpθCA4 were determined by expressing GFP-fused proteins of these TpθCAs in T. pseudonana. As a result, C-terminal GFP fusion proteins of TpθCA1, TpθCA2, and TpθCA3 were all localized in the chloroplast; TpθCA2 was at the central chloroplast area, and the other two TpθCAs were throughout the chloroplast. Immunogold-labeling transmission electron microscopy was further performed for the transformants expressing TpθCA1:GFP and TpθCA2:GFP with anti-GFP-monoclonal antibody. TpθCA1:GFP was localized in the free stroma area, including the peripheral pyrenoid area. TpθCA2:GFP was clearly located as a lined distribution at the central part of the pyrenoid structure, which was most likely the pyrenoid-penetrating thylakoid. Considering the presence of the sequence encoding the N-terminal thylakoid-targeting domain in the TpθCA2 gene, this localization was likely the lumen of the pyrenoid-penetrating thylakoid. On the other hand, TpθCA4:GFP was localized in the cytoplasm. Transcript analysis of these TpθCAs revealed that TpθCA2 and TpθCA3 were upregulated in atmospheric CO2 (0.04% CO2, LC) levels, while TpθCA1 and TpθCA4 were highly induced under 1% CO2 (HC) condition. The genome-editing knockout (KO) of TpθCA1, by CRISPR/Cas9 nickase, gave a silent phenotype in T. pseudonana under LC-HC conditions, which was in sharp agreement with the case of the previously reported TpθCA3 KO. In sharp contrast, TpθCA2 KO is so far unsuccessful, suggesting a housekeeping role of TpθCA2. The silent phenotype of KO strains of stromal CAs suggests that TpαCA1, TpθCA1, and TpθCA3 may have functional redundancy, but different transcript regulations in response to CO2 of these stromal CAs suggest in part their independent roles.
Collapse
Affiliation(s)
- Hermanus Nawaly
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo, 669-1330, Japan
| | - Atsuko Tanaka
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Nishihara, 903-0213, Japan
| | - Yui Toyoshima
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo, 669-1330, Japan
| | - Yoshinori Tsuji
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan
| | - Yusuke Matsuda
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo, 669-1330, Japan.
| |
Collapse
|