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Ueno Y, Shimakawa G, Aikawa S, Miyake C, Akimoto S. Photoprotection mechanisms under different CO 2 regimes during photosynthesis in a green alga Chlorella variabilis. PHOTOSYNTHESIS RESEARCH 2020; 144:397-407. [PMID: 32377933 DOI: 10.1007/s11120-020-00757-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 04/23/2020] [Indexed: 05/28/2023]
Abstract
Oxygenic photosynthesis converts light energy into chemical energy via electron transport and assimilates CO2 in the Calvin-Benson cycle with the chemical energy. Thus, high light and low CO2 conditions induce the accumulation of electrons in the photosynthetic electron transport system, resulting in the formation of reactive oxygen species. To prevent the accumulation of electrons, oxygenic photosynthetic organisms have developed photoprotection mechanisms, including non-photochemical quenching (NPQ) and alternative electron flow (AEF). There are diverse molecular mechanisms underlying NPQ and AEF, and the corresponding molecular actors have been identified and characterized using a model green alga Chlamydomonas reinhardtii. In contrast, detailed information about the photoprotection mechanisms is lacking for other green algal species. In the current study, we examined the photoprotection mechanisms responsive to CO2 in the green alga Chlorella variabilis by combining the analyses of pulse-amplitude-modulated fluorescence, O2 evolution, and the steady-state and time-resolved fluorescence spectra. Under the CO2-limited condition, ΔpH-dependent NPQ occurred in photosystems I and II. Moreover, O2-dependent AEF was also induced. Under the CO2-limited condition with carbon supplementation, NPQ was relaxed and light-harvesting chlorophyll-protein complex II was isolated from both photosystems. In C. variabilis, the O2-dependent AEF and the mechanisms that instantly convert the light-harvesting functions of both photosystems may be important for maintaining efficient photosynthetic activities under various CO2 conditions.
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Affiliation(s)
- Yoshifumi Ueno
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan.
| | - Ginga Shimakawa
- Graduate School of Agricultural Science, Kobe University, Kobe, 657-8501, Japan
- Institute for Integrative Biology of the Cell, CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France
| | - Shimpei Aikawa
- Japan International Research Center for Agricultural Sciences, Tsukuba, 305-8686, Japan
| | - Chikahiro Miyake
- Graduate School of Agricultural Science, Kobe University, Kobe, 657-8501, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan.
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Artier J, Holland SC, Miller NT, Zhang M, Burnap RL. Synthetic DNA system for structure-function studies of the high affinity CO2 uptake NDH-13 protein complex in cyanobacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:1108-1118. [DOI: 10.1016/j.bbabio.2018.06.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 06/22/2018] [Accepted: 06/26/2018] [Indexed: 11/26/2022]
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Shimakawa G, Matsuda Y, Nakajima K, Tamoi M, Shigeoka S, Miyake C. Diverse strategies of O 2 usage for preventing photo-oxidative damage under CO 2 limitation during algal photosynthesis. Sci Rep 2017; 7:41022. [PMID: 28106164 PMCID: PMC5247695 DOI: 10.1038/srep41022] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 12/15/2016] [Indexed: 12/20/2022] Open
Abstract
Photosynthesis produces chemical energy from photon energy in the photosynthetic electron transport and assimilates CO2 using the chemical energy. Thus, CO2 limitation causes an accumulation of excess energy, resulting in reactive oxygen species (ROS) which can cause oxidative damage to cells. O2 can be used as an alternative energy sink when oxygenic phototrophs are exposed to high light. Here, we examined the responses to CO2 limitation and O2 dependency of two secondary algae, Euglena gracilis and Phaeodactylum tricornutum. In E. gracilis, approximately half of the relative electron transport rate (ETR) of CO2-saturated photosynthesis was maintained and was uncoupled from photosynthesis under CO2 limitation. The ETR showed biphasic dependencies on O2 at high and low O2 concentrations. Conversely, in P. tricornutum, most relative ETR decreased in parallel with the photosynthetic O2 evolution rate in response to CO2 limitation. Instead, non-photochemical quenching was strongly activated under CO2 limitation in P. tricornutum. The results indicate that these secondary algae adopt different strategies to acclimatize to CO2 limitation, and that both strategies differ from those utilized by cyanobacteria and green algae. We summarize the diversity of strategies for prevention of photo-oxidative damage under CO2 limitation in cyanobacterial and algal photosynthesis.
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Affiliation(s)
- Ginga Shimakawa
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Yusuke Matsuda
- Research Center for the Development of Intelligent Self-Organized Biomaterials, Research Center for Environmental Bioscience, Department of Bioscience, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Kensuke Nakajima
- Research Center for the Development of Intelligent Self-Organized Biomaterials, Research Center for Environmental Bioscience, Department of Bioscience, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Masahiro Tamoi
- Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Shigeru Shigeoka
- Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Chikahiro Miyake
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
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Shimakawa G, Akimoto S, Ueno Y, Wada A, Shaku K, Takahashi Y, Miyake C. Diversity in photosynthetic electron transport under [CO 2]-limitation: the cyanobacterium Synechococcus sp. PCC 7002 and green alga Chlamydomonas reinhardtii drive an O 2-dependent alternative electron flow and non-photochemical quenching of chlorophyll fluorescence during CO 2-limited photosynthesis. PHOTOSYNTHESIS RESEARCH 2016; 130:293-305. [PMID: 27026083 DOI: 10.1007/s11120-016-0253-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 03/22/2016] [Indexed: 06/05/2023]
Abstract
Some cyanobacteria, but not all, experience an induction of alternative electron flow (AEF) during CO2-limited photosynthesis. For example, Synechocystis sp. PCC 6803 (S. 6803) exhibits AEF, but Synechococcus elongatus sp. PCC 7942 does not. This difference is due to the presence of flavodiiron 2 and 4 proteins (FLV2/4) in S. 6803, which catalyze electron donation to O2. In this study, we observed a low-[CO2] induced AEF in the marine cyanobacterium Synechococcus sp. PCC 7002 that lacks FLV2/4. The AEF shows high affinity for O2, compared with AEF mediated by FLV2/4 in S. 6803, and can proceed under extreme low [O2] (about a few µM O2). Further, the transition from CO2-saturated to CO2-limited photosynthesis leads a preferential excitation of PSI to PSII and increased non-photochemical quenching of chlorophyll fluorescence. We found that the model green alga Chlamydomonas reinhardtii also has an O2-dependent AEF showing the same affinity for O2 as that in S. 7002. These data represent the diverse molecular mechanisms to drive AEF in cyanobacteria and green algae. In this paper, we further discuss the diversity, the evolution, and the physiological function of strategy to CO2-limitation in cyanobacterial and green algal photosynthesis.
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Affiliation(s)
- Ginga Shimakawa
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan.
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
- Molecular Photoscience Research Center, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
| | - Ayumi Wada
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
| | - Keiichiro Shaku
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
| | - Yuichiro Takahashi
- Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, 700-8530, Japan
| | - Chikahiro Miyake
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
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Holland SC, Artier J, Miller NT, Cano M, Yu J, Ghirardi ML, Burnap RL. Impacts of genetically engineered alterations in carbon sink pathways on photosynthetic performance. ALGAL RES 2016. [DOI: 10.1016/j.algal.2016.09.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Shaku K, Shimakawa G, Hashiguchi M, Miyake C. Reduction-Induced Suppression of Electron Flow (RISE) in the Photosynthetic Electron Transport System of Synechococcus elongatus PCC 7942. PLANT & CELL PHYSIOLOGY 2016; 57:1443-1453. [PMID: 26707729 DOI: 10.1093/pcp/pcv198] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 12/02/2015] [Indexed: 05/24/2023]
Abstract
Accumulation of electrons under conditions of environmental stress produces a reduced state in the photosynthetic electron transport (PET) system and causes the reduction of O2 by PSI in the thylakoid membranes to produce the reactive oxygen species superoxide radical, which irreversibly inactivates PSI. This study aims to elucidate the molecular mechanism for the oxidation of reaction center Chl of PSI, P700, after saturated pulse (SP) light illumination of the cyanobacterium Synechococcus elongatus PCC 7942 under steady-state photosynthetic conditions. Both P700 and NADPH were transiently oxidized after SP light illumination under CO2-depleted photosynthesis conditions. In contrast, the Chl fluorescence intensity transiently increased. Compared with the wild type, the increase in Chl fluorescence and the oxidations of P700 and NADPH were greatly enhanced in a mutant (Δflv1/3) deficient in the genes encoding FLAVODIIRON 1 (FLV1) and FLV3 proteins even under high photosynthetic conditions. Furthermore, oxidation of Cyt f was also observed in the mutant. After SP light illumination, a transient suppression of O2 evolution was also observed in Δflv1/3. From these observations, we propose that the reduction in the plastquinone (PQ) pool suppresses linear electron flow at the Cyt b6/f complex, which we call the reduction-induced suppression of electron flow (RISE) in the PET system. The accumulation of the reduced form of PQ probably suppresses turnover of the Q cycle in the Cyt b6/f complex.
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Affiliation(s)
- Keiichiro Shaku
- Department of Biological and Environmental Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501 Japan
| | - Ginga Shimakawa
- Department of Biological and Environmental Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501 Japan
| | - Masaki Hashiguchi
- Department of Biological and Environmental Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501 Japan
| | - Chikahiro Miyake
- Department of Biological and Environmental Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501 Japan
- Core Research for Environmental Science and Technology, Japan Science and Technology Agency, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076 Japan
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Shimakawa G, Shaku K, Nishi A, Hayashi R, Yamamoto H, Sakamoto K, Makino A, Miyake C. FLAVODIIRON2 and FLAVODIIRON4 proteins mediate an oxygen-dependent alternative electron flow in Synechocystis sp. PCC 6803 under CO2-limited conditions. PLANT PHYSIOLOGY 2015; 167:472-80. [PMID: 25540330 PMCID: PMC4326736 DOI: 10.1104/pp.114.249987] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 12/23/2014] [Indexed: 05/22/2023]
Abstract
This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available.
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Affiliation(s)
- Ginga Shimakawa
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan (G.S., K.Sh., A.N., R.H., K.Sa., C.M.);Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (H.Y.);Department of Agriculture, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan (A.M.); andCore Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan (A.M., C.M.)
| | - Keiichiro Shaku
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan (G.S., K.Sh., A.N., R.H., K.Sa., C.M.);Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (H.Y.);Department of Agriculture, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan (A.M.); andCore Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan (A.M., C.M.)
| | - Akiko Nishi
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan (G.S., K.Sh., A.N., R.H., K.Sa., C.M.);Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (H.Y.);Department of Agriculture, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan (A.M.); andCore Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan (A.M., C.M.)
| | - Ryosuke Hayashi
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan (G.S., K.Sh., A.N., R.H., K.Sa., C.M.);Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (H.Y.);Department of Agriculture, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan (A.M.); andCore Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan (A.M., C.M.)
| | - Hiroshi Yamamoto
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan (G.S., K.Sh., A.N., R.H., K.Sa., C.M.);Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (H.Y.);Department of Agriculture, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan (A.M.); andCore Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan (A.M., C.M.)
| | - Katsuhiko Sakamoto
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan (G.S., K.Sh., A.N., R.H., K.Sa., C.M.);Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (H.Y.);Department of Agriculture, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan (A.M.); andCore Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan (A.M., C.M.)
| | - Amane Makino
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan (G.S., K.Sh., A.N., R.H., K.Sa., C.M.);Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (H.Y.);Department of Agriculture, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan (A.M.); andCore Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan (A.M., C.M.)
| | - Chikahiro Miyake
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan (G.S., K.Sh., A.N., R.H., K.Sa., C.M.);Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan (H.Y.);Department of Agriculture, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan (A.M.); andCore Research for Evolutional Science and Technology, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan (A.M., C.M.)
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Holland SC, Kappell AD, Burnap RL. Redox changes accompanying inorganic carbon limitation in Synechocystis sp. PCC 6803. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:355-363. [PMID: 25490207 DOI: 10.1016/j.bbabio.2014.12.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 11/26/2014] [Accepted: 12/02/2014] [Indexed: 12/27/2022]
Abstract
Inorganic carbon (Ci) is the major sink for photosynthetic reductant in organisms capable of oxygenic photosynthesis. In the absence of abundant Ci, the cyanobacterium Synechocystis sp. strain PCC6803 expresses a high affinity Ci acquisition system, the CO2-concentrating mechanisms (CCM), controlled by the transcriptional regulator CcmR and the metabolites NADP+ and α-ketoglutarate, which act as co-repressors of CcmR by modulating its DNA binding. The CCM thus responds to internal cellular redox changes during the transition from Ci-replete to Ci-limited conditions. However, the actual changes in the metabolic state of the NADPH/NADP+ system that occur during the transition to Ci-limited conditions remain ill-defined. Analysis of changes in the redox state of cells experiencing Ci limitation reveals systematic changes associated with physiological adjustments and a trend towards the quinone and NADP pools becoming highly reduced. A rapid and persistent increase in F0 was observed in cells reaching the Ci-limited state, as was the induction of photoprotective fluorescence quenching. Systematic changes in the fluorescence induction transients were also observed. As with Chl fluorescence, a transient reduction of the NADPH pool ('M' peak), is assigned to State 2→State 1 transition associated with increased electron flow to NADP+. This was followed by a characteristic decline, which was abolished by Ci limitation or inhibition of the Calvin-Benson-Bassham (CBB) cycle and is thus assigned to the activation of the CBB cycle. The results are consistent with the proposed regulation of the CCM and provide new information on the nature of the Chl and NADPH fluorescence induction curves.
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Affiliation(s)
- Steven C Holland
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
| | - Anthony D Kappell
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
| | - Robert L Burnap
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA.
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Wensel P, Helms G, Hiscox B, Davis WC, Kirchhoff H, Bule M, Yu L, Chen S. Isolation, characterization, and validation of oleaginous, multi-trophic, and haloalkaline-tolerant microalgae for two-stage cultivation. ALGAL RES 2014. [DOI: 10.1016/j.algal.2013.12.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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Ihnken S, Kromkamp JC, Beardall J, Silsbe GM. State-transitions facilitate robust quantum yields and cause an over-estimation of electron transport in Dunaliella tertiolecta cells held at the CO₂ compensation point and re-supplied with DIC. PHOTOSYNTHESIS RESEARCH 2014; 119:257-272. [PMID: 24135997 DOI: 10.1007/s11120-013-9937-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Accepted: 10/01/2013] [Indexed: 06/02/2023]
Abstract
Photosynthetic energy consumption and non-photosynthetic energy quenching processes are inherently linked. Both processes must be controlled by the cell to allow cell maintenance and growth, but also to avoid photodamage. We used the chlorophyte algae Dunaliella tertiolecta to investigate how the interactive regulation of photosynthetic and non-photosynthetic pathways varies along dissolved inorganic carbon (DIC) and photon flux gradients. Specifically, cells were transferred to DIC-deplete media to reach a CO₂ compensation before being re-supplied with DIC at various concentrations and different photon flux levels. Throughout these experiments we monitored and characterized the photophysiological responses using pulse amplitude modulated fluorescence, oxygen evolution, 77 K fluorescence emission spectra, and fast-repetition rate fluorometry. O₂ uptake was not significantly stimulated at DIC depletion, which suggests that O₂ production rates correspond to assimilatory photosynthesis. Fluorescence-based measures of relative electron transport rates (rETRs) over-estimated oxygen-based photosynthetic measures due to a strong state-transitional response that facilitated high effective quantum yields. Adoption of an alternative fluorescence-based rETR calculation that accounts for state-transitions resulted in improved linear oxygen versus rETR correlation. This study shows the extraordinary capacity of D. tertiolecta to maintain stable effective quantum yields by flexible regulation of state-transitions. Uncertainties about the control mechanisms of state-transitions are presented.
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Affiliation(s)
- Sven Ihnken
- Netherlands Institute for Sea Research, NIOZ, Postbus 140, 4400 AC, Yerseke, The Netherlands
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Jähnichen S, Ihle T, Petzoldt T, Benndorf J. Impact of inorganic carbon availability on microcystin production by Microcystis aeruginosa PCC 7806. Appl Environ Microbiol 2007; 73:6994-7002. [PMID: 17827326 PMCID: PMC2074933 DOI: 10.1128/aem.01253-07] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Batch culture experiments with the cyanobacterium Microcystis aeruginosa PCC 7806 were performed in order to test the hypothesis that microcystins (MCYSTs) are produced in response to a relative deficiency of intracellular inorganic carbon (C(i,i)). In the first experiment, MCYST production was studied under increased C(i,i) deficiency conditions, achieved by restricting sodium-dependent bicarbonate uptake through replacement of sodium bicarbonate in the medium with its potassium analog. The same experimental approach was used in a second experiment to compare the response of the wild-type strain M. aeruginosa PCC 7806 with its mcyB mutant, which lacks the ability to produce MCYSTs. In a third experiment, the impact of varying the C(i,i) status on MCYST production was examined without suppressing the sodium-dependent bicarbonate transporter; instead, a detailed investigation of a dark-light cycle was performed. In all experiments, a relative C(i,i) deficiency was indicated by an elevated variable fluorescence signal and led to enhanced phycocyanin cell quotas. Higher MCYST cell quotas (in the first and third experiments) and increased total (intracellular plus extracellular) MCYST production (in the first experiment) were detected with increased C(i,i) deficiency. Furthermore, the MCYST-producing wild-type strain and its mcyB mutant showed basically the same response to restrained inorganic carbon uptake, with elevated variable fluorescence and phycocyanin cell quotas with increased C(i,i) deficiency. The response of the wild type, however, was distinctly stronger and also included elevated chlorophyll a cell quotas. These differences indicate the limited ability of the mutant to adapt to low-C(i,i) conditions. We concluded that MCYSTs may be involved in enhancing the efficiency of the adaptation of the photosynthetic apparatus to fluctuating inorganic carbon conditions in cyanobacterial cells.
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Affiliation(s)
- Sabine Jähnichen
- Dresden University of Technology, Institute of Hydrobiology, 01062 Dresden, Germany.
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Suzuki K, Onodera H. Adaptation of a Chlamydomonas mutant with reduced rate of photorespiration to different concentrations of CO2. ACTA ACUST UNITED AC 2005. [DOI: 10.1139/b05-068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It has been widely accepted that Chlamydomonas reinhardtii cells utilize inorganic carbon very efficiently for photosynthesis by operating a CO2-concentrating mechanism (CCM) under conditions of limited CO2. To help define the mechanism, 7FR2N, one of the suppressor double mutants of phosphoglycolate phosphatase-deficient (pgp1) mutants that have a reduced photorespiration rate (RPR) was crossed with wild-type strains to generate the strain N21 as a single RPR mutant. The comparison of photosynthetic characteristics with wild-type strains after the cells adapted to different concentrations of CO2 revealed that photosynthetic affinity for inorganic carbon was higher than that in wild-type strains after adaptation to concentrations between 50 µL·L1 CO2 and 5% CO2. Chlorophyll fluorescence parameters were also compared, and the biggest difference between N21 and the wild-type strains was observed in the photochemical quenching and effective quantum yield of photosystem II (ΔF/Fm′) at the CO2 compensation point. These values in N21 increased in a similar manner to the photosynthetic affinity for CO2, and increased significantly when the cells adapted to low-CO2 levels, whereas the values in the wild-type strains were apparently lower without any significant changes, regardless of the CO2 concentrations to which they were adapted. Although it was not clear if a nonphotochemical quenching parameter (NPQ) in N21 was higher than that in wild-type strains, NPQ increased coincidentally with the increase in photosynthetic affinity for inorganic carbon when the CO2 concentrations to which the strains were adapted decreased, in both the mutant and wild-type strain, suggesting that this form of NPQ reflects the operation of CCM in certain conditions. Possible candidates for the RPR mutation and the relationship between CCM and photosynthetic electron flow are discussed.Key words: Chlamydomonas reinhardtii, chlorophyll fluorescence, CO2-concentrating mechanism, low-CO2 responsive gene, phosphoglycolate phosphatase, photorespiration.
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Abstract
Many microorganisms possess inducible mechanisms that concentrate CO2 at the carboxylation site, compensating for the relatively low affinity of Rubisco for its substrate, and allowing acclimation to a wide range of CO2 concentrations. The organization of the carboxysomes in prokaryotes and of the pyrenoids in eukaryotes, and the presence of membrane mechanisms for inorganic carbon (Ci) transport, are central to the concentrating mechanism. The presence of multiple Ci transporting systems in cyanobacteria has been indicated. Certain genes involved in structural organization, Ci transport and the energization of the latter have been identified. Massive Ci fluxes associated with the CO2-concentrating mechanism have wide-reaching ecological and geochemical implications.
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Affiliation(s)
- Aaron Kaplan
- Department of Plant Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904 Israel; e-mail:
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Campbell D, Hurry V, Clarke AK, Gustafsson P, Oquist G. Chlorophyll fluorescence analysis of cyanobacterial photosynthesis and acclimation. Microbiol Mol Biol Rev 1998; 62:667-83. [PMID: 9729605 PMCID: PMC98930 DOI: 10.1128/mmbr.62.3.667-683.1998] [Citation(s) in RCA: 412] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cyanobacteria are ecologically important photosynthetic prokaryotes that also serve as popular model organisms for studies of photosynthesis and gene regulation. Both molecular and ecological studies of cyanobacteria benefit from real-time information on photosynthesis and acclimation. Monitoring in vivo chlorophyll fluorescence can provide noninvasive measures of photosynthetic physiology in a wide range of cyanobacteria and cyanolichens and requires only small samples. Cyanobacterial fluorescence patterns are distinct from those of plants, because of key structural and functional properties of cyanobacteria. These include significant fluorescence emission from the light-harvesting phycobiliproteins; large and rapid changes in fluorescence yield (state transitions) which depend on metabolic and environmental conditions; and flexible, overlapping respiratory and photosynthetic electron transport chains. The fluorescence parameters FV/FM, FV'/FM',qp,qN, NPQ, and phiPS II were originally developed to extract information from the fluorescence signals of higher plants. In this review, we consider how the special properties of cyanobacteria can be accommodated and used to extract biologically useful information from cyanobacterial in vivo chlorophyll fluorescence signals. We describe how the pattern of fluorescence yield versus light intensity can be used to predict the acclimated light level for a cyanobacterial population, giving information valuable for both laboratory and field studies of acclimation processes. The size of the change in fluorescence yield during dark-to-light transitions can provide information on respiration and the iron status of the cyanobacteria. Finally, fluorescence parameters can be used to estimate the electron transport rate at the acclimated growth light intensity.
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Affiliation(s)
- D Campbell
- Department of Biology, Mount Allison University, Sackville, New Brunswick E4L 1G7, Canada.
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