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Chen Z, Yuan ZW, Luo WX, Wu X, Pan JL, Yin YQ, Shao HC, Xu K, Li WZ, Hu YL, Wang Z, Gao KS, Chen XW. UV-A radiation increases biomass yield by enhancing energy flow and carbon assimilation in the edible cyanobacterium Nostoc sphaeroides. Appl Environ Microbiol 2024; 90:e0211023. [PMID: 38391210 PMCID: PMC10952460 DOI: 10.1128/aem.02110-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 01/25/2024] [Indexed: 02/24/2024] Open
Abstract
Ultraviolet (UV) A radiation (315-400 nm) is the predominant component of solar UV radiation that reaches the Earth's surface. However, the underlying mechanisms of the positive effects of UV-A on photosynthetic organisms have not yet been elucidated. In this study, we investigated the effects of UV-A radiation on the growth, photosynthetic ability, and metabolome of the edible cyanobacterium Nostoc sphaeroides. Exposures to 5-15 W m-2 (15-46 µmol photons m-2 s-1) UV-A and 4.35 W m-2 (20 μmol photons m-2 s-1) visible light for 16 days significantly increased the growth rate and biomass production of N. sphaeroides cells by 18%-30% and 15%-56%, respectively, compared to the non-UV-A-acclimated cells. Additionally, the UV-A-acclimated cells exhibited a 1.8-fold increase in the cellular nicotinamide adenine dinucleotide phosphate (NADP) pool with an increase in photosynthetic capacity (58%), photosynthetic efficiency (24%), QA re-oxidation, photosystem I abundance, and cyclic electron flow (87%), which further led to an increase in light-induced NADPH generation (31%) and ATP content (83%). Moreover, the UV-A-acclimated cells showed a 2.3-fold increase in ribulose-1,5-bisphosphate carboxylase/oxygenase activity, indicating an increase in their carbon-fixing capacity. Gas chromatography-mass spectrometry-based metabolomics further revealed that UV-A radiation upregulated the energy-storing carbon metabolism, as evidenced by the enhanced accumulation of sugars, fatty acids, and citrate in the UV-A-acclimated cells. Therefore, our results demonstrate that UV-A radiation enhances energy flow and carbon assimilation in the cyanobacterium N. sphaeroides.IMPORTANCEUltraviolet (UV) radiation exerts harmful effects on photo-autotrophs; however, several studies demonstrated the positive effects of UV radiation, especially UV-A radiation (315-400 nm), on primary productivity. Therefore, understanding the underlying mechanisms associated with the promotive effects of UV-A radiation on primary productivity can facilitate the application of UV-A for CO2 sequestration and lead to the advancement of photobiological sciences. In this study, we used the cyanobacterium Nostoc sphaeroides, which has an over 1,700-year history of human use as food and medicine, to explore its photosynthetic acclimation response to UV-A radiation. As per our knowledge, this is the first study to demonstrate that UV-A radiation increases the biomass yield of N. sphaeroides by enhancing energy flow and carbon assimilation. Our findings provide novel insights into UV-A-mediated photosynthetic acclimation and provide a scientific basis for the application of UV-A radiation for optimizing light absorption capacity and enhancing CO2 sequestration in the frame of a future CO2 neutral, circular, and sustainable bioeconomy.
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Affiliation(s)
- Zhen Chen
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Zu-Wen Yuan
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Wei-Xin Luo
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Xun Wu
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Jin-Long Pan
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Yong-Qi Yin
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Hai-Chen Shao
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Kui Xu
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Wei-Zhi Li
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Yuan-Liang Hu
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Zhe Wang
- Hubei Key Laboratory of Quality and Safety of Traditional Chinese Medicine Health Food, Jing Brand Co., Ltd., Daye, Hubei, China
| | - Kun-Shan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, China
| | - Xiong-Wen Chen
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
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Akhtar P, Balog-Vig F, Kuntam S, Tóth SZ, Lambrev PH. Function of iron-stress-induced protein A in cyanobacterial cells with monomeric and trimeric photosystem I. PLANT PHYSIOLOGY 2024; 194:1397-1410. [PMID: 37850879 DOI: 10.1093/plphys/kiad562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 09/12/2023] [Accepted: 09/24/2023] [Indexed: 10/19/2023]
Abstract
The acclimation of cyanobacteria to iron deficiency is crucial for their survival in natural environments. In response to iron deficiency, many cyanobacterial species induce the production of a pigment-protein complex called iron-stress-induced protein A (IsiA). IsiA proteins associate with photosystem I (PSI) and can function as light-harvesting antennas or dissipate excess energy. They may also serve as chlorophyll storage during iron limitation. In this study, we examined the functional role of IsiA in cells of Synechocystis sp. PCC 6803 grown under iron limitation conditions by measuring the cellular IsiA content and its capability to transfer energy to PSI. We specifically tested the effect of the oligomeric state of PSI by comparing wild-type (WT) Synechocystis sp. PCC 6803 with mutants lacking specific subunits of PSI, namely PsaL/PsaI (PSI subunits XI/VIII) and PsaF/PsaJ (PSI subunits III/IX). Time-resolved fluorescence spectroscopy revealed that IsiA formed functional PSI3-IsiA18 supercomplexes, wherein IsiA effectively transfers energy to PSI on a timescale of 10 ps at room temperature-measured in isolated complexes and in vivo-confirming the primary role of IsiA as an accessory light-harvesting antenna to PSI. However, a notable fraction (40%) remained unconnected to PSI, supporting the notion of a dual functional role of IsiA. Cells with monomeric PSI under iron deficiency contained, on average, only 3 to 4 IsiA complexes bound to PSI. These results show that IsiA can transfer energy to trimeric and monomeric PSI but to varying degrees and that the acclimatory production of IsiA under iron stress is controlled by its ability to perform its light-harvesting function.
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Affiliation(s)
- Parveen Akhtar
- HUN-REN Biological Research Centre, Szeged, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
| | - Fanny Balog-Vig
- HUN-REN Biological Research Centre, Szeged, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
| | - Soujanya Kuntam
- HUN-REN Biological Research Centre, Szeged, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
| | - Szilvia Z Tóth
- HUN-REN Biological Research Centre, Szeged, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
| | - Petar H Lambrev
- HUN-REN Biological Research Centre, Szeged, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
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3
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Colussi A, Bokhari SNH, Mijovilovich A, Koník P, Küpper H. Acclimation to medium-level non-lethal iron limitation: Adjustment of electron flow around the PSII and metalloprotein expression in Trichodesmium erythraeum IMS101. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2024; 1865:149015. [PMID: 37742749 DOI: 10.1016/j.bbabio.2023.149015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/26/2023]
Abstract
The aim of this study was to investigate how acclimation to medium-level, long-term, non-lethal iron limitation changes the electron flux around the Photosystem II of the oceanic diazotroph Trichodesmium erythraeum IMS101. Fe availability of about 5× and 100× lower than a replete level, i.e. conditions common in the natural environment of this cyanobacterium, were applied in chemostats. The response of the cells was studied not only in terms of growth, but also mechanistically, measuring the chlorophyll fluorescence of dark-adapted filaments via imaging fluorescence kinetic microscopy (FKM) with 0.3 ms time resolution. Combining these measurements with those of metal binding to proteins via online coupling of metal-free HPLC (size exclusion chromatography SEC) to sector-field ICP-MS allowed to track the fate of the photosystems, together with other metalloproteins. General increase of fluorescence has been observed, with the consequent decrease in the quantum yields φ of the PSII, while the efficiency ψ of the electron flux between PSII and the PSI remained surprisingly unchanged. This indicates the ability of Trichodesmium to cope with a situation that makes assembling the many iron clusters in Photosystem I a particular challenge, as shown by decreasing ratios of Fe to Mg in these proteins. The negative effect of Fe limitation on PSII may also be due to its fast turnover. A broader view was obtained from metalloproteomics via HPLC-ICP-MS, revealing a differential protein expression pattern under iron limitation with a drastic down-regulation especially of iron-containing proteins and some increase in low MW metal-binding complexes.
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Affiliation(s)
- Antonio Colussi
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, Laboratory of Plant Biophysics and Biochemistry, České Budějovice, Czech Republic; University of South Bohemia, Faculty of Sciences, Department of Experimental Plant Biology, České Budějovice, Czech Republic
| | - Syed Nadeem Hussain Bokhari
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, Laboratory of Plant Biophysics and Biochemistry, České Budějovice, Czech Republic
| | - Ana Mijovilovich
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, Laboratory of Plant Biophysics and Biochemistry, České Budějovice, Czech Republic
| | - Peter Koník
- University of South Bohemia, Faculty of Sciences, Department of Chemistry, České Budějovice, Czech Republic
| | - Hendrik Küpper
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, Laboratory of Plant Biophysics and Biochemistry, České Budějovice, Czech Republic; University of South Bohemia, Faculty of Sciences, Department of Experimental Plant Biology, České Budějovice, Czech Republic.
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4
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Browning TJ, Saito MA, Garaba SP, Wang X, Achterberg EP, Moore CM, Engel A, Mcllvin MR, Moran D, Voss D, Zielinski O, Tagliabue A. Persistent equatorial Pacific iron limitation under ENSO forcing. Nature 2023; 621:330-335. [PMID: 37587345 PMCID: PMC10499608 DOI: 10.1038/s41586-023-06439-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 07/14/2023] [Indexed: 08/18/2023]
Abstract
Projected responses of ocean net primary productivity to climate change are highly uncertain1. Models suggest that the climate sensitivity of phytoplankton nutrient limitation in the low-latitude Pacific Ocean plays a crucial role1-3, but this is poorly constrained by observations4. Here we show that changes in physical forcing drove coherent fluctuations in the strength of equatorial Pacific iron limitation through multiple El Niño/Southern Oscillation (ENSO) cycles, but that this was overestimated twofold by a state-of-the-art climate model. Our assessment was enabled by first using a combination of field nutrient-addition experiments, proteomics and above-water hyperspectral radiometry to show that phytoplankton physiological responses to iron limitation led to approximately threefold changes in chlorophyll-normalized phytoplankton fluorescence. We then exploited the >18-year satellite fluorescence record to quantify climate-induced nutrient limitation variability. Such synoptic constraints provide a powerful approach for benchmarking the realism of model projections of net primary productivity to climate changes.
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Affiliation(s)
- Thomas J Browning
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
| | - Mak A Saito
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Shungudzemwoyo P Garaba
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Xuechao Wang
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Eric P Achterberg
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - C Mark Moore
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK
| | - Anja Engel
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | | | - Dawn Moran
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Daniela Voss
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Oliver Zielinski
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
- German Research Center for Artificial Intelligence (DFKI), Oldenburg, Germany
- Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Warnemünde, Germany
| | - Alessandro Tagliabue
- Department of Earth, Ocean, Ecological Sciences, University of Liverpool, Liverpool, UK
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5
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Wang T, Li J, Jing H, Qin S. Picocyanobacterial Synechococcus in marine ecosystem: Insights from genetic diversity, global distribution, and potential function. MARINE ENVIRONMENTAL RESEARCH 2022; 177:105622. [PMID: 35429822 DOI: 10.1016/j.marenvres.2022.105622] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/01/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
Marine Synechococcus, a main group of picocyanobacteria, has been ubiquitously observed across the global oceans. Synechococcus exhibits high phylogenetical and phenotypical diversity, and horizontal gene transfer makes its genetic evolution much more intricate. With the development of measurement technologies and analysis methods, the genomic information and niche partition of each Synechococcus lineage tend to be precisely described, but the global analysis is still lacking. Therefore, it is necessary to summarize existing studies and integrate published data to gain a comprehensive understanding of Synechococcus on genetic variation, niche division, and potential functions. In this review, the maximum likelihood trees are constructed based on existing sequence data, including both phylogenetic and pigmentary gene markers. The global distribution characteristics of abundance, lineages, and pigment types are concluded through pooled analysis of more than 700 samples obtained from approximately 50 scientific research cruises. The potential functions of Synechococcus are explored in element cycles and biological interactions. Future work on Synechococcus is suggested to focus on not only elucidating the nature of Synechococcus biodiversity but also demonstrating its interactions with the ecosystem by combining bioinformatics and macroscopic isotope-labeled environmental parameters.
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Affiliation(s)
- Ting Wang
- Key Laboratory of Coastal Biology and Biological Resource Conservation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264000, China; CAS Key Laboratory for Experimental Study under Deep-sea Extreme Conditions, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jialin Li
- Key Laboratory of Coastal Biology and Biological Resource Conservation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264000, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Hongmei Jing
- CAS Key Laboratory for Experimental Study under Deep-sea Extreme Conditions, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China
| | - Song Qin
- Key Laboratory of Coastal Biology and Biological Resource Conservation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264000, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
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6
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Camoying MG, Thoms S, Geuer JK, Koch BP, Bischof K, Trimborn S. In contrast to diatoms, cryptophytes are susceptible to iron limitation, but not to ocean acidification. PHYSIOLOGIA PLANTARUM 2022; 174:e13614. [PMID: 35199361 DOI: 10.1111/ppl.13614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/09/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Previous field studies in the Southern Ocean (SO) indicated an increased occurrence and dominance of cryptophytes over diatoms due to climate change. To gain a better mechanistic understanding of how the two ecologically important SO phytoplankton groups cope with ocean acidification (OA) and iron (Fe) availability, we chose two common representatives of Antarctic waters, the cryptophyte Geminigera cryophila and the diatom Pseudo-nitzschia subcurvata. Both species were grown at 2°C under different pCO2 (400 vs. 900 μatm) and Fe (0.6 vs. 1.2 nM) conditions. For P. subcurvata, an additional high pCO2 level was applied (1400 μatm). At ambient pCO2 under low Fe supply, growth of G. cryophila almost stopped while it remained unaffected in P. subcurvata. Under high Fe conditions, OA was not beneficial for P. subcurvata, but stimulated growth and carbon production of G. cryophila. Under low Fe supply, P. subcurvata coped much better with OA than the cryptophyte, but invested more energy into photoacclimation. Our study reveals that Fe limitation was detrimental for the growth of G. cryophila and suppressed the positive OA effect. The diatom was efficient in coping with low Fe, but was stressed by OA while both factors together strongly impacted its growth. The distinct physiological response of both species to OA and Fe limitation explains their occurrence in the field. Based on our results, Fe availability is an important modulator of OA effects on SO phytoplankton, with different implications on the occurrence of cryptophytes and diatoms in the future.
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Affiliation(s)
- Marianne G Camoying
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Silke Thoms
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Jana K Geuer
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Boris P Koch
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
- Department of Technology, University of Applied Sciences Bremerhaven, Bremerhaven, Germany
| | - Kai Bischof
- Marine Botany & MARUM, University of Bremen, Bremen, Germany
| | - Scarlett Trimborn
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
- Marine Botany & MARUM, University of Bremen, Bremen, Germany
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7
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Pagnone A, Koch F, Pausch F, Trimborn S. The Southern Ocean diatom Pseudo-nitzschia subcurvata flourished better under simulated glacial than interglacial ocean conditions: Combined effects of CO2 and iron. PLoS One 2021; 16:e0260649. [PMID: 34890411 PMCID: PMC8664213 DOI: 10.1371/journal.pone.0260649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 11/12/2021] [Indexed: 11/19/2022] Open
Abstract
The 'Iron Hypothesis' suggests a fertilization of the Southern Ocean by increased dust deposition in glacial times. This promoted high primary productivity and contributed to lower atmospheric pCO2. In this study, the diatom Pseudo-nitzschia subcurvata, known to form prominent blooms in the Southern Ocean, was grown under simulated glacial and interglacial climatic conditions to understand how iron (Fe) availability (no Fe or Fe addition) in conjunction with different pCO2 levels (190 and 290 μatm) influences growth, particulate organic carbon (POC) production and photophysiology. Under both glacial and interglacial conditions, the diatom grew with similar rates. In comparison, glacial conditions (190 μatm pCO2 and Fe input) favored POC production by P. subcurvata while under interglacial conditions (290 μatm pCO2 and Fe deficiency) POC production was reduced, indicating a negative effect caused by higher pCO2 and low Fe availability. Under interglacial conditions, the diatom had, however, thicker silica shells. Overall, our results show that the combination of higher Fe availability with low pCO2, present during the glacial ocean, was beneficial for the diatom P. subcurvata, thus contributing more to primary production during glacial compared to interglacial times. Under the interglacial ocean conditions, on the other hand, the diatom could have contributed to higher carbon export due to its higher degree of silicification.
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Affiliation(s)
- Anna Pagnone
- EcoTrace, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Florian Koch
- EcoTrace, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Franziska Pausch
- EcoTrace, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Scarlett Trimborn
- EcoTrace, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
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Jia A, Zheng Y, Chen H, Wang Q. Regulation and Functional Complexity of the Chlorophyll-Binding Protein IsiA. Front Microbiol 2021; 12:774107. [PMID: 34867913 PMCID: PMC8635728 DOI: 10.3389/fmicb.2021.774107] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 10/25/2021] [Indexed: 11/17/2022] Open
Abstract
As the oldest known lineage of oxygen-releasing photosynthetic organisms, cyanobacteria play the key roles in helping shaping the ecology of Earth. Iron is an ideal transition metal for redox reactions in biological systems. Cyanobacteria frequently encounter iron deficiency due to the environmental oxidation of ferrous ions to ferric ions, which are highly insoluble at physiological pH. A series of responses, including architectural changes to the photosynthetic membranes, allow cyanobacteria to withstand this condition and maintain photosynthesis. Iron-stress-induced protein A (IsiA) is homologous to the cyanobacterial chlorophyll (Chl)-binding protein, photosystem II core antenna protein CP43. IsiA is the major Chl-containing protein in iron-starved cyanobacteria, binding up to 50% of the Chl in these cells, and this Chl can be released from IsiA for the reconstruction of photosystems during the recovery from iron limitation. The pigment–protein complex (CPVI-4) encoded by isiA was identified and found to be expressed under iron-deficient conditions nearly 30years ago. However, its precise function is unknown, partially due to its complex regulation; isiA expression is induced by various types of stresses and abnormal physiological states besides iron deficiency. Furthermore, IsiA forms a range of complexes that perform different functions. In this article, we describe progress in understanding the regulation and functions of IsiA based on laboratory research using model cyanobacteria.
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Affiliation(s)
- Anqi Jia
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Yanli Zheng
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Hui Chen
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Qiang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
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9
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Rai R, Singh S, Rai KK, Raj A, Sriwastaw S, Rai LC. Regulation of antioxidant defense and glyoxalase systems in cyanobacteria. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 168:353-372. [PMID: 34700048 DOI: 10.1016/j.plaphy.2021.09.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 09/09/2021] [Accepted: 09/28/2021] [Indexed: 05/19/2023]
Abstract
Oxidative stress is common consequence of abiotic stress in plants as well as cyanobacteria caused by generation of reactive oxygen species (ROS), an inevitable product of respiration and photosynthetic electron transport. ROS act as signalling molecule at low concentration however, when its production exceeds the endurance capacity of antioxidative defence system, the organisms suffer oxidative stress. A highly toxic metabolite, methylglyoxal (MG) is also produced in cyanobacteria in response to various abiotic stresses which consequently augment the ensuing oxidative damage. Taking recourse to the common lineage of eukaryotic plants and cyanobacteria, it would be worthwhile to explore the regulatory role of glyoxalase system and antioxidative defense mechanism in combating abiotic stress in cyanobacteria. This review provides comprehensive information on the complete glyoxalase system (GlyI, GlyII and GlyIII) in cyanobacteria. Furthermore, it elucidates the recent understanding regarding the production of ROS and MG, noteworthy link between intracellular MG and ROS and its detoxification via synchronization of antioxidants (enzymatic and non-enzymatic) and glyoxalase systems using glutathione (GSH) as common co-factor.
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Affiliation(s)
- Ruchi Rai
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Shilpi Singh
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Krishna Kumar Rai
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Alka Raj
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Sonam Sriwastaw
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - L C Rai
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
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10
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Iron transport in cyanobacteria - from molecules to communities. Trends Microbiol 2021; 30:229-240. [PMID: 34175176 DOI: 10.1016/j.tim.2021.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 06/01/2021] [Accepted: 06/01/2021] [Indexed: 11/22/2022]
Abstract
Iron is an essential micronutrient for the ecologically important photoautotrophic cyanobacteria which are found across diverse aquatic environments. Low concentrations and poor bioavailability of certain iron species exert a strong control on cyanobacterial growth, affecting ecosystem structure and biogeochemical cycling. Here, we review the iron-acquisition pathways cyanobacteria utilize for overcoming these challenges. As the molecular details of cyanobacterial iron transport are being uncovered, an overall scheme of how cyanobacteria handle and exploit this scarce and redox-active micronutrient is emerging. Importantly, the range of biological solutions used by cyanobacteria to increase iron fluxes goes beyond transport and includes behavioral traits of colonial cyanobacteria and intricate cyanobacteria-bacteria interactions.
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Abstract
Oxygenic photosynthetic organisms have evolved a multitude of mechanisms for protection against high-light stress. IsiA, a chlorophyll a-binding cyanobacterial protein, serves as an accessory antenna complex for photosystem I. Intriguingly, IsiA can also function as an independent pigment protein complex in the thylakoid membrane and facilitate the dissipation of excess energy, providing photoprotection. The molecular basis of the IsiA-mediated excitation quenching mechanism remains poorly understood. In this study, we demonstrate that IsiA uses a novel cysteine-mediated process to quench excitation energy. The single cysteine in IsiA in the cyanobacterium Synechocystis sp. strain PCC 6803 was converted to a valine. Ultrafast fluorescence spectroscopic analysis showed that this single change abolishes the excitation energy quenching ability of IsiA, thus providing direct evidence of the crucial role of this cysteine residue in energy dissipation from excited chlorophylls. Under stress conditions, the mutant cells exhibited enhanced light sensitivity, indicating that the cysteine-mediated quenching process is critically important for photoprotection.
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12
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Schoffman H, Brown WM, Paltiel Y, Keren N, Gauger EM. Structure-based Hamiltonian model for IsiA uncovers a highly robust pigment-protein complex. J R Soc Interface 2020; 17:20200399. [PMID: 32842892 PMCID: PMC7482578 DOI: 10.1098/rsif.2020.0399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/04/2020] [Indexed: 11/12/2022] Open
Abstract
The iron stress-induced protein A (IsiA) is a source of interest and debate in biological research. The IsiA supercomplex, binding over 200 chlorophylls, assembles in multimeric rings around photosystem I (PSI). Recently, the IsiA-PSI structure from Synechocystis sp. PCC 6803 was resolved to 3.48 Å. Based on this structure, we created a model simulating a single excitation event in an IsiA monomer. This model enabled us to calculate the fluorescence and the localization of the excitation in the IsiA structure. To further examine this system, noise was introduced to the model in two forms-thermal and positional. Introducing noise highlights the functional differences in the system between cryogenic temperatures and biologically relevant temperatures. Our results show that the energetics of the IsiA pigment-protein complex are very robust at room temperature. Nevertheless, shifts in the position of specific chlorophylls lead to large changes in their optical and fluorescence properties. Based on these results, we discuss the implication of highly robust structures, with potential for serving different roles in a context-dependent manner, on our understanding of the function and evolution of photosynthetic processes.
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Affiliation(s)
- Hanan Schoffman
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - William M. Brown
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Yossi Paltiel
- Applied Physics Department, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Nir Keren
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Erik M. Gauger
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
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13
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Zhao LS, Huokko T, Wilson S, Simpson DM, Wang Q, Ruban AV, Mullineaux CW, Zhang YZ, Liu LN. Structural variability, coordination and adaptation of a native photosynthetic machinery. NATURE PLANTS 2020; 6:869-882. [PMID: 32665651 DOI: 10.1038/s41477-020-0694-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 05/14/2020] [Indexed: 05/12/2023]
Abstract
Cyanobacterial thylakoid membranes represent the active sites for both photosynthetic and respiratory electron transport. We used high-resolution atomic force microscopy to visualize the native organization and interactions of photosynthetic complexes within the thylakoid membranes from the model cyanobacterium Synechococcus elongatus PCC 7942. The thylakoid membranes are heterogeneous and assemble photosynthetic complexes into functional domains to enhance their coordination and regulation. Under high light, the chlorophyll-binding proteins IsiA are strongly expressed and associate with Photosystem I (PSI), forming highly variable IsiA-PSI supercomplexes to increase the absorption cross-section of PSI. There are also tight interactions of PSI with Photosystem II (PSII), cytochrome b6f, ATP synthase and NAD(P)H dehydrogenase complexes. The organizational variability of these photosynthetic supercomplexes permits efficient linear and cyclic electron transport as well as bioenergetic regulation. Understanding the organizational landscape and environmental adaptation of cyanobacterial thylakoid membranes may help inform strategies for engineering efficient photosynthetic systems and photo-biofactories.
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Affiliation(s)
- Long-Sheng Zhao
- State Key Laboratory of Microbial Technology, and Marine Biotechnology Research Center, Shandong University, Qingdao, China
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
- College of Marine Life Sciences and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Tuomas Huokko
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Sam Wilson
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Deborah M Simpson
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Qiang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Alexander V Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Conrad W Mullineaux
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Yu-Zhong Zhang
- State Key Laboratory of Microbial Technology, and Marine Biotechnology Research Center, Shandong University, Qingdao, China.
- College of Marine Life Sciences and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China.
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China.
| | - Lu-Ning Liu
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK.
- College of Marine Life Sciences and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China.
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14
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Johansson S, Stephenson P, Edwards R, Yoshida K, Moore C, Terauchi R, Zubkov M, Terry M, Bibby T. Isolation and molecular characterisation of Dunaliella tertiolecta with truncated light-harvesting antenna for enhanced photosynthetic efficiency. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.101917] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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15
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Gao F. Iron-Sulfur Cluster Biogenesis and Iron Homeostasis in Cyanobacteria. Front Microbiol 2020; 11:165. [PMID: 32184761 PMCID: PMC7058544 DOI: 10.3389/fmicb.2020.00165] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 01/23/2020] [Indexed: 01/23/2023] Open
Abstract
Iron–sulfur (Fe–S) clusters are ancient and ubiquitous cofactors and are involved in many important biological processes. Unlike the non-photosynthetic bacteria, cyanobacteria have developed the sulfur utilization factor (SUF) mechanism as their main assembly pathway for Fe–S clusters, supplemented by the iron–sulfur cluster and nitrogen-fixing mechanisms. The SUF system consists of cysteine desulfurase SufS, SufE that can enhance SufS activity, SufBC2D scaffold complex, carrier protein SufA, and regulatory repressor SufR. The S source for the Fe–S cluster assembly mainly originates from L-cysteine, but the Fe donor remains elusive. This minireview mainly focuses on the biogenesis pathway of the Fe–S clusters in cyanobacteria and its relationship with iron homeostasis. Future challenges of studying Fe–S clusters in cyanobacteria are also discussed.
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Affiliation(s)
- Fudan Gao
- College of Life Sciences, Shanghai Normal University, Shanghai, China
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16
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Cao P, Cao D, Si L, Su X, Tian L, Chang W, Liu Z, Zhang X, Li M. Structural basis for energy and electron transfer of the photosystem I-IsiA-flavodoxin supercomplex. NATURE PLANTS 2020; 6:167-176. [PMID: 32042157 DOI: 10.1038/s41477-020-0593-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 01/06/2020] [Indexed: 05/10/2023]
Abstract
Under iron-deficiency stress, which occurs frequently in natural aquatic environments, cyanobacteria reduce the amount of iron-enriched proteins, including photosystem I (PSI) and ferredoxin (Fd), and upregulate the expression of iron-stress-induced proteins A and B (IsiA and flavodoxin (Fld)). Multiple IsiAs function as the peripheral antennae that encircle the PSI core, whereas Fld replaces Fd as the electron receptor of PSI. Here, we report the structures of the PSI3-IsiA18-Fld3 and PSI3-IsiA18 supercomplexes from Synechococcus sp. PCC 7942, revealing features that are different from the previously reported PSI structures, and a sophisticated pigment network that involves previously unobserved pigment molecules. Spectroscopic results demonstrated that IsiAs are efficient light harvesters for PSI. Three Flds bind symmetrically to the trimeric PSI core-we reveal the detailed interaction and the electron transport path between PSI and Fld. Our results provide a structural basis for understanding the mechanisms of light harvesting, energy transfer and electron transport of cyanobacterial PSI under stressed conditions.
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Affiliation(s)
- Peng Cao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Duanfang Cao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Long Si
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
- University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Xiaodong Su
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Lijin Tian
- Institute of Botany, Chinese Academy of Sciences, Beijing, P. R. China
| | - Wenrui Chang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
- University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Zhenfeng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
- University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China.
- University of Chinese Academy of Sciences, Beijing, P. R. China.
- Center for Biological Imaging, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China.
| | - Mei Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China.
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17
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Schoffman H, Keren N. Function of the IsiA pigment-protein complex in vivo. PHOTOSYNTHESIS RESEARCH 2019; 141:343-353. [PMID: 30929163 DOI: 10.1007/s11120-019-00638-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 03/18/2019] [Indexed: 06/09/2023]
Abstract
The acclimation of cyanobacterial photosynthetic apparatus to iron deficiency is crucial for their performance under limiting conditions. In many cyanobacterial species, one of the major responses to iron deficiency is the induction of isiA. The function of the IsiA pigment-protein complex has been the subject of intensive research. In this study of the model Synechocystis sp. PCC 6803 strain, we probe the accumulation of the pigment-protein complex and its effects on in vivo photosynthetic performance. We provide evidence that in this organism the dominant factor controlling IsiA accumulation is the intracellular iron concentration and not photo-oxidative stress or redox poise. These findings support the use of IsiA as a tool for assessing iron bioavailability in environmental studies. We also present evidence demonstrating that the IsiA pigment-protein complex exerts only small effects on the performance of the reaction centers. We propose that its major function is as a storage depot able to hold up to 50% of the cellular chlorophyll content during transition into iron limitation. During recovery from iron limitation, chlorophyll is released from the complex and used for the reconstruction of photosystems. Therefore, the IsiA pigment-protein complex can play a critical role not only when cells transition into iron limitation, but also in supporting efficient recovery of the photosynthetic apparatus in the transition back out of the iron-limited state.
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Affiliation(s)
- Hanan Schoffman
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, Israel
| | - Nir Keren
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, Israel.
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18
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Hamilton TL. The trouble with oxygen: The ecophysiology of extant phototrophs and implications for the evolution of oxygenic photosynthesis. Free Radic Biol Med 2019; 140:233-249. [PMID: 31078729 DOI: 10.1016/j.freeradbiomed.2019.05.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 04/03/2019] [Accepted: 05/02/2019] [Indexed: 12/11/2022]
Abstract
The ability to harvest light to drive chemical reactions and gain energy provided microbes access to high energy electron donors which fueled primary productivity, biogeochemical cycles, and microbial evolution. Oxygenic photosynthesis is often cited as the most important microbial innovation-the emergence of oxygen-evolving photosynthesis, aided by geologic events, is credited with tipping the scale from a reducing early Earth to an oxygenated world that eventually lead to complex life. Anoxygenic photosynthesis predates oxygen-evolving photosynthesis and played a key role in developing and fine-tuning the photosystem architecture of modern oxygenic phototrophs. The release of oxygen as a by-product of metabolic activity would have caused oxidative damage to anaerobic microbiota that evolved under the anoxic, reducing conditions of early Earth. Photosynthetic machinery is particularly susceptible to the adverse effects of oxygen and reactive oxygen species and these effects are compounded by light. As a result, phototrophs employ additional detoxification mechanisms to mitigate oxidative stress and have evolved alternative oxygen-dependent enzymes for chlorophyll biosynthesis. Phylogenetic reconstruction studies and biochemical characterization suggest photosynthetic reactions centers, particularly in Cyanobacteria, evolved to both increase efficiency of electron transfer and avoid photodamage caused by chlorophyll radicals that is acute in the presence of oxygen. Here we review the oxygen and reactive oxygen species detoxification mechanisms observed in extant anoxygenic and oxygenic photosynthetic bacteria as well as the emergence of these mechanisms over evolutionary time. We examine the distribution of phototrophs in modern systems and phylogenetic reconstructions to evaluate the emergence of mechanisms to mediate oxidative damage and highlight changes in photosystems and reaction centers, chlorophyll biosynthesis, and niche space in response to oxygen production. This synthesis supports an emergence of H2S-driven anoxygenic photosynthesis in Cyanobacteria prior to the evolution of oxygenic photosynthesis and underscores a role for the former metabolism in fueling fine-tuning of the oxygen evolving complex and mechanisms to repair oxidative damage. In contrast, we note the lack of elaborate mechanisms to deal with oxygen in non-cyanobacterial anoxygenic phototrophs suggesting these microbes have occupied similar niche space throughout Earth's history.
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Affiliation(s)
- Trinity L Hamilton
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, 55108, USA; Biotechnology Institute, University of Minnesota, St. Paul, MN, 55108, USA.
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19
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Li Q, Huisman J, Bibby TS, Jiao N. Biogeography of Cyanobacterial isiA Genes and Their Link to Iron Availability in the Ocean. Front Microbiol 2019; 10:650. [PMID: 31024472 PMCID: PMC6460047 DOI: 10.3389/fmicb.2019.00650] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 03/14/2019] [Indexed: 11/15/2022] Open
Abstract
The cyanobacterial iron-stress-inducible isiA gene encodes a chlorophyll-binding protein that provides flexibility in photosynthetic strategy enabling cells to acclimate to low iron availability. Here, we report on the diversity and abundance of isiA genes from 14 oceanic stations encompassing large natural gradients in iron availability. Synechococcus CRD1 and CRD2-like isiA genes were ubiquitously identified from tropical and subtropical waters of the Pacific, Atlantic, and Indian Oceans. The relative abundance of isiA-containing Synechococcus cells ranged from less than 10% of the total Synechococcus population in regions where iron is replete such as the North Atlantic subtropical gyre, to over 80% in low-iron but high-nitrate regions of the eastern equatorial Pacific. Interestingly, Synechococcus populations in regions with both low iron and low nitrate concentrations such as the subtropical gyres in the North Pacific and South Atlantic had a low relative abundance of the isiA gene. Indeed, fitting our data into a multiple regression model showed that ∼80% of the variation in isiA relative abundances can be explained by nitrate and iron concentrations, whereas no other environmental variables (temperature, salinity, Chl a) had a significant effect. Hence, isiA has a predictable biogeographical distribution, consistent with the perceived biological role of IsiA as an adaptation to low-iron conditions. Understanding such photosynthetic strategies is critical to our ability to accurately estimate primary production and map nutrient limitation on global scales.
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Affiliation(s)
- Qian Li
- State Key Laboratory of Marine Environmental Sciences, Institute of Marine Microbes and Ecosphere, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
- Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, Netherlands
- Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawai’i at Mānoa, Honolulu, HI, United States
| | - Jef Huisman
- Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, Netherlands
| | - Thomas S. Bibby
- School of Ocean and Earth Science, National Oceanography Centre Southampton, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom
| | - Nianzhi Jiao
- State Key Laboratory of Marine Environmental Sciences, Institute of Marine Microbes and Ecosphere, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
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20
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Blanco-Ameijeiras S, Moisset SAM, Trimborn S, Campbell DA, Heiden JP, Hassler CS. Elemental Stoichiometry and Photophysiology Regulation of Synechococcus sp. PCC7002 Under Increasing Severity of Chronic Iron Limitation. PLANT & CELL PHYSIOLOGY 2018; 59:1803-1816. [PMID: 29860486 DOI: 10.1093/pcp/pcy097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
Iron (Fe) is an essential cofactor for many metabolic enzymes of photoautotrophs. Although Fe limits phytoplankton productivity in broad areas of the ocean, phytoplankton have adapted their metabolism and growth to survive in these conditions. Using the euryhaline cyanobacterium Synechococcus sp. PCC7002, we investigated the physiological responses to long-term acclimation to four levels of Fe availability representative of the contemporary ocean (36.7, 3.83, 0.47 and 0.047 pM Fe'). With increasing severity of Fe limitation, Synechococcus sp. cells gradually decreased their volume and growth while increasing their energy allocation into organic carbon and nitrogen cellular pools. Furthermore, the total cellular content of pigments decreased. Additionally, with increasing severity of Fe limitation, intertwined responses of PSII functional cross-section (σPSII), re-oxidation time of the plastoquinone primary acceptor QA (τ) and non-photochemical quenching revealed a shift in the photophysiological response between mild to strong Fe limitation compared with severe limitation. Under mild and strong Fe limitation, there was a decrease in linear electron transport accompanied by progressive loss of state transitions. Under severe Fe limitation, state transitions seemed to be largely supplanted by alternative electron pathways. In addition, mechanisms to dissipate energy excess and minimize oxidative stress associated with high irradiances increased with increasing severity of Fe limitation. Overall, our results establish the sequence of physiological strategies adopted by the cells under increasing severity of chronic Fe limitation, within a range of Fe concentrations relevant to modern ocean biogeochemistry.
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Affiliation(s)
- Sonia Blanco-Ameijeiras
- Department F.-A. Forel for Environmental and Aquatic Sciences, Faculty of Science, University of Geneva, Boulevard Carl-Vogt 66, Geneva 4, Switzerland
| | - Sophie A M Moisset
- Department F.-A. Forel for Environmental and Aquatic Sciences, Faculty of Science, University of Geneva, Boulevard Carl-Vogt 66, Geneva 4, Switzerland
| | - Scarlett Trimborn
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, Germany
- Marine Botany, University of Bremen, Leobener Strasse NW2-A, Bremen, Germany
| | - Douglas A Campbell
- Biology, Faculty of Science, Mount Allison University, Sackville, NB, Canada
| | - Jasmin P Heiden
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, Germany
- Marine Botany, University of Bremen, Leobener Strasse NW2-A, Bremen, Germany
| | - Christel S Hassler
- Department F.-A. Forel for Environmental and Aquatic Sciences, Faculty of Science, University of Geneva, Boulevard Carl-Vogt 66, Geneva 4, Switzerland
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21
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Boatman TG, Oxborough K, Gledhill M, Lawson T, Geider RJ. An Integrated Response of Trichodesmium erythraeum IMS101 Growth and Photo-Physiology to Iron, CO 2, and Light Intensity. Front Microbiol 2018; 9:624. [PMID: 29755417 PMCID: PMC5932364 DOI: 10.3389/fmicb.2018.00624] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/19/2018] [Indexed: 11/13/2022] Open
Abstract
We have assessed how varying CO2 (180, 380, and 720 μatm) and growth light intensity (40 and 400 μmol photons m-2 s-1) affected Trichodesmium erythraeum IMS101 growth and photophysiology over free iron (Fe') concentrations between 20 and 9,600 pM. We found significant iron dependencies of growth rate and the initial slope and maximal relative PSII electron transport rates (rPm). Under iron-limiting concentrations, high-light increased growth rates and rPm; possibly indicating a lower allocation of resources to iron-containing photosynthetic proteins. Higher CO2 increased growth rates across all iron concentrations, enabled growth to occur at lower Fe' concentrations, increased rPm and lowered the iron half saturation constants for growth (Km). We attribute these CO2 responses to the operation of the CCM and the ATP spent/saved for CO2 uptake and transport at low and high CO2, respectively. It seems reasonable to conclude that T. erythraeum IMS101 can exhibit a high degree of phenotypic plasticity in response to CO2, light intensity and iron-limitation. These results are important given predictions of increased dissolved CO2 and water column stratification (i.e., higher light exposures) over the coming decades.
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Affiliation(s)
- Tobias G Boatman
- School of Biological Sciences, University of Essex, Colchester, United Kingdom
| | - Kevin Oxborough
- Chelsea Technologies Group Ltd, West Molesey, United Kingdom
| | - Martha Gledhill
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, United Kingdom.,GEOMAR, Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Tracy Lawson
- School of Biological Sciences, University of Essex, Colchester, United Kingdom
| | - Richard J Geider
- School of Biological Sciences, University of Essex, Colchester, United Kingdom
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22
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Zer H, Margulis K, Georg J, Shotland Y, Kostova G, Sultan LD, Hess WR, Keren N. Resequencing of a mutant bearing an iron starvation recovery phenotype defines Slr1658 as a new player in the regulatory network of a model cyanobacterium. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:235-245. [PMID: 29161470 DOI: 10.1111/tpj.13770] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 10/26/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
Photosynthetic microorganisms encounter an erratic nutrient environment characterized by periods of iron limitation and sufficiency. Surviving in such an environment requires mechanisms for handling these transitions. Our study identified a regulatory system involved in the process of recovery from iron limitation in cyanobacteria. We set out to study the role of bacterioferritin co-migratory proteins during transitions in iron bioavailability in the cyanobacterium Synechocystis sp. PCC 6803 using knockout strains coupled with physiological and biochemical measurements. One of the mutants displayed slow recovery from iron limitation. However, we discovered that the cause of the phenotype was not the intended knockout but rather the serendipitous selection of a mutation in an unrelated locus, slr1658. Bioinformatics analysis suggested similarities to two-component systems and a possible regulatory role. Transcriptomic analysis of the recovery from iron limitation showed that the slr1658 mutation had an extensive effect on the expression of genes encoding regulatory proteins, proteins involved in the remodeling and degradation of the photosynthetic apparatus and proteins modulating electron transport. Most significantly, expression of the cyanobacterial homologue of the cyclic electron transport protein PGR5 was upregulated 1000-fold in slr1658 disruption mutants. pgr5 transcripts in the Δslr1658 mutant retained these high levels under a range of stress and recovery conditions. The results suggest that slr1658 is part of a regulatory operon that, among other aspects, affects the regulation of alternative electron flow. Disruption of its function has deleterious results under oxidative stress promoting conditions.
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Affiliation(s)
- Hagit Zer
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Ketty Margulis
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Jens Georg
- Faculty of Biology, Genetics and Experimental Bioinformatics, University of Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany
| | - Yoram Shotland
- Department of Chemical Engineering, Shamoon College of Engineering, Beer Sheva, 84100, Israel
| | - Gergana Kostova
- Faculty of Biology, Genetics and Experimental Bioinformatics, University of Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany
| | - Laure D Sultan
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Wolfgang R Hess
- Faculty of Biology, Genetics and Experimental Bioinformatics, University of Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany
- Freiburg Institute for Advanced Studies, University of Freiburg, Albertstr. 19, D-79104, Freiburg, Germany
| | - Nir Keren
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
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23
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Chen HYS, Liberton M, Pakrasi HB, Niedzwiedzki DM. Reevaluating the mechanism of excitation energy regulation in iron-starved cyanobacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:249-258. [DOI: 10.1016/j.bbabio.2017.01.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/20/2016] [Accepted: 01/06/2017] [Indexed: 12/18/2022]
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24
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Ma F, Zhang X, Zhu X, Li T, Zhan J, Chen H, He C, Wang Q. Dynamic Changes of IsiA-Containing Complexes during Long-Term Iron Deficiency in Synechocystis sp. PCC 6803. MOLECULAR PLANT 2017; 10:143-154. [PMID: 27777125 DOI: 10.1016/j.molp.2016.10.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 10/05/2016] [Accepted: 10/13/2016] [Indexed: 05/26/2023]
Abstract
Iron stress-induced protein A (IsiA), a major chlorophyll-binding protein in the thylakoid membrane, is significantly induced under iron deficiency conditions. Using immunoblot analysis and 77 K fluorescence spectroscopy combined with sucrose gradient fractionation, we monitored dynamic changes of IsiA-containing complexes in Synechocystis sp. PCC 6803 during exposure to long-term iron deficiency. Within 3 days of exposure to iron deficiency conditions, the initially induced free IsiA proteins preferentially conjugated to PS I trimer to form IsiA18-PS I trimers, which serve as light energy collectors for efficiently transmitting energy to PS I. With prolonged iron deficiency, IsiA proteins assembled either into IsiA aggregates or into two other types of IsiA-PS I supercomplexes, namely IsiA-PS I high fluorescence supercomplex (IHFS) and IsiA-PS I low fluorescence supercomplex (ILFS). Further analysis revealed a role for IsiA as an energy dissipater in the IHFS and as an energy collector in the ILFS. The trimeric structure of PS I mediated by PsaL was found to be indispensable for the formation of IHFS/ILFS. Dynamic changes in IsiA-containing complexes in cyanobacteria during long-term iron deficiency may represent an adaptation to iron limitation stress for flexible light energy distribution, which balances electron transfer between PS I and PS II, thus minimizing photooxidative damage.
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Affiliation(s)
- Fei Ma
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, China; College of Life Sciences, University of the Chinese Academy of Sciences, Beijing 100039, China
| | - Xin Zhang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, China; College of Life Sciences, University of the Chinese Academy of Sciences, Beijing 100039, China
| | - Xi Zhu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, China; College of Life Sciences, University of the Chinese Academy of Sciences, Beijing 100039, China
| | - Tianpei Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, China; College of Life Sciences, University of the Chinese Academy of Sciences, Beijing 100039, China
| | - Jiao Zhan
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Hui Chen
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Chenliu He
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Qiang Wang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, China.
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Shen G, Gan F, Bryant DA. The siderophilic cyanobacterium Leptolyngbya sp. strain JSC-1 acclimates to iron starvation by expressing multiple isiA-family genes. PHOTOSYNTHESIS RESEARCH 2016; 128:325-340. [PMID: 27071628 DOI: 10.1007/s11120-016-0257-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 03/24/2016] [Indexed: 06/05/2023]
Abstract
In the evolution of different cyanobacteria performing oxygenic photosynthesis, the core complexes of the two photosystems were highly conserved. However, cyanobacteria exhibit significant diversification in their light-harvesting complexes and have flexible regulatory mechanisms to acclimate to changes in their growth environments. In the siderophilic, filamentous cyanobacterium, Leptolyngbya sp. strain JSC-1, five different isiA-family genes occur in two gene clusters. During acclimation to Fe limitation, relative transcript levels for more than 600 genes increased more than twofold. Relative transcript levels were ~250 to 300 times higher for the isiA1 gene cluster (isiA1-isiB-isiC), and ~440- to 540-fold for the isiA2-isiA3-isiA4-cpcG2-isiA5 gene cluster after 48 h of iron starvation. Chl-protein complexes were isolated and further purified from cells grown under Fe-replete and Fe-depleted conditions. A single class of particles, trimeric PSI, was identified by image analysis of electron micrographs of negatively stained PSI complexes from Fe-replete cells. However, three major classes of particles were observed for the Chl-protein supercomplexes from cells grown under iron starvation conditions. Based on LC-MS-MS analyses, the five IsiA-family proteins were found in the largest supercomplexes together with core components of the two photosystems; however, IsiA5 was not present in complexes in which only the core subunits of PSI were detected. IsiA5 belongs to the same clade as PcbC proteins in a phylogenetic classification, and it is proposed that IsiA5 is most likely involved in supercomplexes containing PSII dimers. IsiA4, which is a fusion of an IsiA domain and a C-terminal PsaL domain, was found together with IsiA1, IsiA2, and IsiA3 in complexes with monomeric PSI. The data indicate that horizontal gene transfer, gene duplication, and divergence have played important roles in the adaptive evolution of this cyanobacterium to iron starvation conditions.
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Affiliation(s)
- Gaozhong Shen
- Department of Biochemistry and Molecular Biology, 4406 Althouse Laboratory, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Fei Gan
- Department of Biochemistry and Molecular Biology, 4406 Althouse Laboratory, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, 4406 Althouse Laboratory, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA.
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Schoffman H, Lis H, Shaked Y, Keren N. Iron-Nutrient Interactions within Phytoplankton. FRONTIERS IN PLANT SCIENCE 2016; 7:1223. [PMID: 27588022 PMCID: PMC4989028 DOI: 10.3389/fpls.2016.01223] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/02/2016] [Indexed: 05/04/2023]
Abstract
Iron limits photosynthetic activity in up to one third of the world's oceans and in many fresh water environments. When studying the effects of Fe limitation on phytoplankton or their adaptation to low Fe environments, we must take into account the numerous cellular processes within which this micronutrient plays a central role. Due to its flexible redox chemistry, Fe is indispensable in enzymatic catalysis and electron transfer reactions and is therefore closely linked to the acquisition, assimilation and utilization of essential resources. Iron limitation will therefore influence a wide range of metabolic pathways within phytoplankton, most prominently photosynthesis. In this review, we map out four well-studied interactions between Fe and essential resources: nitrogen, manganese, copper and light. Data was compiled from both field and laboratory studies to shed light on larger scale questions such as the connection between metabolic pathways and ambient iron levels and the biogeographical distribution of phytoplankton species.
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Affiliation(s)
- Hanan Schoffman
- Department of Plant and Environmental Sciences, Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Hagar Lis
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of JerusalemJerusalem, Israel
| | - Yeala Shaked
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of JerusalemJerusalem, Israel
- Interuniversity Institute for Marine Sciences in EilatEilat, Israel
| | - Nir Keren
- Department of Plant and Environmental Sciences, Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
- *Correspondence: Nir Keren,
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Snow JT, Polyviou D, Skipp P, Chrismas NAM, Hitchcock A, Geider R, Moore CM, Bibby TS. Quantifying Integrated Proteomic Responses to Iron Stress in the Globally Important Marine Diazotroph Trichodesmium. PLoS One 2015; 10:e0142626. [PMID: 26562022 PMCID: PMC4642986 DOI: 10.1371/journal.pone.0142626] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 10/23/2015] [Indexed: 02/03/2023] Open
Abstract
Trichodesmium is a biogeochemically important marine cyanobacterium, responsible for a significant proportion of the annual 'new' nitrogen introduced into the global ocean. These non-heterocystous filamentous diazotrophs employ a potentially unique strategy of near-concurrent nitrogen fixation and oxygenic photosynthesis, potentially burdening Trichodesmium with a particularly high iron requirement due to the iron-binding proteins involved in these processes. Iron availability may therefore have a significant influence on the biogeography of Trichodesmium. Previous investigations of molecular responses to iron stress in this keystone marine microbe have largely been targeted. Here a holistic approach was taken using a label-free quantitative proteomics technique (MSE) to reveal a sophisticated multi-faceted proteomic response of Trichodesmium erythraeum IMS101 to iron stress. Increased abundances of proteins known to be involved in acclimation to iron stress and proteins known or predicted to be involved in iron uptake were observed, alongside decreases in the abundances of iron-binding proteins involved in photosynthesis and nitrogen fixation. Preferential loss of proteins with a high iron content contributed to overall reductions of 55-60% in estimated proteomic iron requirements. Changes in the abundances of iron-binding proteins also suggested the potential importance of alternate photosynthetic pathways as Trichodesmium reallocates the limiting resource under iron stress. Trichodesmium therefore displays a significant and integrated proteomic response to iron availability that likely contributes to the ecological success of this species in the ocean.
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Affiliation(s)
- Joseph T. Snow
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, United Kingdom
- Stem Cell and Leukaemia Proteomics Laboratory, Manchester Academic Health Science Centre, The University of Manchester, Wolfson Molecular Imaging Centre, Manchester, United Kingdom
- * E-mail:
| | - Despo Polyviou
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, United Kingdom
| | - Paul Skipp
- Centre for Proteomic Research, University of Southampton, Southampton, United Kingdom
| | - Nathan A. M. Chrismas
- School of Geographical Sciences, University of Bristol, University Road, Clifton, Bristol, United Kingdom
| | - Andrew Hitchcock
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Richard Geider
- School of Biological Sciences, University of Essex, Colchester, United Kingdom
| | - C. Mark Moore
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, United Kingdom
| | - Thomas S. Bibby
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, United Kingdom
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Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton. PLoS One 2015; 10:e0133235. [PMID: 26171963 PMCID: PMC4501554 DOI: 10.1371/journal.pone.0133235] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 06/25/2015] [Indexed: 12/30/2022] Open
Abstract
Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETRRCII, mol e- mol RCII-1 s-1) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal – oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETRRCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements.
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29
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Salomon E, Keren N. Acclimation to environmentally relevant Mn concentrations rescues a cyanobacterium from the detrimental effects of iron limitation. Environ Microbiol 2015; 17:2090-8. [DOI: 10.1111/1462-2920.12826] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/13/2015] [Accepted: 02/22/2015] [Indexed: 11/26/2022]
Affiliation(s)
- Eitan Salomon
- Department of Plant and Environmental Sciences; The Alexander Silberman Institute of Life Sciences; The Hebrew University of Jerusalem; Jerusalem Israel
| | - Nir Keren
- Department of Plant and Environmental Sciences; The Alexander Silberman Institute of Life Sciences; The Hebrew University of Jerusalem; Jerusalem Israel
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30
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Pierella Karlusich JJ, Ceccoli RD, Graña M, Romero H, Carrillo N. Environmental selection pressures related to iron utilization are involved in the loss of the flavodoxin gene from the plant genome. Genome Biol Evol 2015; 7:750-67. [PMID: 25688107 PMCID: PMC5322553 DOI: 10.1093/gbe/evv031] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Oxidative stress and iron limitation represent the grim side of life in an oxygen-rich atmosphere. The versatile electron transfer shuttle ferredoxin, an iron-sulfur protein, is particularly sensitive to these hardships, and its downregulation under adverse conditions severely compromises survival of phototrophs. Replacement of ferredoxin by a stress-resistant isofunctional carrier, flavin-containing flavodoxin, is a widespread strategy employed by photosynthetic microorganisms to overcome environmental adversities. The flavodoxin gene was lost in the course of plant evolution, but its reintroduction in transgenic plants confers increased tolerance to environmental stress and iron starvation, raising the question as to why a genetic asset with obvious adaptive value was not kept by natural selection. Phylogenetic analyses reveal that the evolutionary history of flavodoxin is intricate, with several horizontal gene transfer events between distant organisms, including Eukarya, Bacteria, and Archaea. The flavodoxin gene is unevenly distributed in most algal lineages, with flavodoxin-containing species being overrepresented in iron-limited regions and scarce or absent in iron-rich environments. Evaluation of cyanobacterial genomic and metagenomic data yielded essentially the same results, indicating that there was little selection pressure to retain flavodoxin in iron-rich coastal/freshwater phototrophs. Our results show a highly dynamic evolution pattern of flavodoxin tightly connected to the bioavailability of iron. Evidence presented here also indicates that the high concentration of iron in coastal and freshwater habitats may have facilitated the loss of flavodoxin in the freshwater ancestor of modern plants during the transition of photosynthetic organisms from the open oceans to the firm land.
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Affiliation(s)
- Juan J Pierella Karlusich
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-Universidad Nacional de Rosario, Ocampo y Esmeralda, Rosario, Argentina
| | - Romina D Ceccoli
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-Universidad Nacional de Rosario, Ocampo y Esmeralda, Rosario, Argentina Present address: Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario; CONICET, Rosario, Argentina
| | - Martín Graña
- Unidad de Bioinformática, Institut Pasteur Montevideo, Uruguay
| | - Héctor Romero
- Departamento de Ecología y Evolución, Facultad de Ciencias/CURE, Universidad de la República, Montevideo, Uruguay
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-Universidad Nacional de Rosario, Ocampo y Esmeralda, Rosario, Argentina
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31
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Sharon S, Salomon E, Kranzler C, Lis H, Lehmann R, Georg J, Zer H, Hess WR, Keren N. The hierarchy of transition metal homeostasis: Iron controls manganese accumulation in a unicellular cyanobacterium. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1990-1997. [DOI: 10.1016/j.bbabio.2014.09.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 09/17/2014] [Accepted: 09/18/2014] [Indexed: 01/04/2023]
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Cheng D, He Q. PfsR is a key regulator of iron homeostasis in Synechocystis PCC 6803. PLoS One 2014; 9:e101743. [PMID: 25010795 PMCID: PMC4092027 DOI: 10.1371/journal.pone.0101743] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 06/10/2014] [Indexed: 02/04/2023] Open
Abstract
Iron is an essential cofactor in numerous cellular processes. The iron deficiency in the oceans affects the primary productivity of phytoplankton including cyanobacteria. In this study, we examined the function of PfsR, a TetR family transcriptional regulator, in iron homeostasis of the cyanobacterium Synechocystis PCC 6803. Compared with the wild type, the pfsR deletion mutant displayed stronger tolerance to iron limitation and accumulated significantly more chlorophyll a, carotenoid, and phycocyanin under iron-limiting conditions. The mutant also maintained more photosystem I and photosystem II complexes than the wild type after iron deprivation. In addition, the activities of photosystem I and photosystem II were much higher in pfsR deletion mutant than in wild-type cells under iron-limiting conditions. The transcripts of pfsR were enhanced by iron limitation and inactivation of the gene affected pronouncedly expression of fut genes (encoding a ferric iron transporter), feoB (encoding a ferrous iron transporter), bfr genes (encoding bacterioferritins), ho genes (encoding heme oxygenases), isiA (encoding a chlorophyll-binding protein), and furA (encoding a ferric uptake regulator). The iron quota in pfsR deletion mutant cells was higher than in wild-type cells both before and after exposure to iron limitation. Electrophoretic mobility shift assays showed that PfsR bound to its own promoter and thereby auto-regulated its own expression. These data suggest that PfsR is a critical regulator of iron homeostasis.
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Affiliation(s)
- Dan Cheng
- Department of Applied Science, University of Arkansas at Little Rock, Little Rock, Arkansas, United States of America
| | - Qingfang He
- Department of Applied Science, University of Arkansas at Little Rock, Little Rock, Arkansas, United States of America
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33
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Brading P, Warner ME, Smith DJ, Suggett DJ. Contrasting modes of inorganic carbon acquisition amongst Symbiodinium (Dinophyceae) phylotypes. THE NEW PHYTOLOGIST 2013; 200:432-442. [PMID: 23815769 DOI: 10.1111/nph.12379] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Accepted: 05/23/2013] [Indexed: 06/02/2023]
Abstract
Growing concerns over ocean acidification have highlighted the need to critically understand inorganic carbon acquisition and utilization in marine microalgae. Here, we contrast these characteristics for the first time between two genetically distinct dinoflagellate species of the genus Symbiodinium (phylotypes A13 and A20) that live in symbiosis with reef-forming corals. Both phylotypes were grown in continuous cultures under identical environmental conditions. Rubisco was measured using quantitative Western blots, and radioisotopic (14) C uptake was used to characterize light- and total carbon dioxide (TCO2 )-dependent carbon fixation, as well as inorganic carbon species preference and external carbonic anhydrase activity. A13 and A20 exhibited similar rates of carbon fixation despite cellular concentrations of Rubisco being approximately four-fold greater in A13. The uptake of CO2 over HCO3 - was found to support the majority of carbon fixation in both phylotypes. However, A20 was also able to indirectly utilize HCO3 - by first converting it to CO2 via external carbonic anhydrase. These results show that adaptive differences in inorganic carbon acquisition have evolved within the Symbiodinium genus, which thus carries fundamental implications as to how this functionally key genus will respond to ocean acidification, but could also represent a key trait factor that influences their productivity when in hospite of their coral hosts.
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Affiliation(s)
- Patrick Brading
- Coral Reef Research Unit, Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Mark E Warner
- College of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Rd, Lewes, DE 19958, USA
| | - David J Smith
- Coral Reef Research Unit, Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - David J Suggett
- Coral Reef Research Unit, Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
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34
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Fraser JM, Tulk SE, Jeans JA, Campbell DA, Bibby TS, Cockshutt AM. Photophysiological and photosynthetic complex changes during iron starvation in Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942. PLoS One 2013; 8:e59861. [PMID: 23527279 PMCID: PMC3602374 DOI: 10.1371/journal.pone.0059861] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/19/2013] [Indexed: 12/13/2022] Open
Abstract
Iron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abundances and photophysiological parameters in the model cyanobacteria Synechococcus PCC 7942 and Synechocystis PCC 6803 over a 120 hour time course of iron deprivation. The iron stress induced protein (IsiA) accumulated to high levels within 48 h of the onset of iron deprivation, reaching a molar ratio of ∼42 IsiA : Photosystem I in Synechococcus PCC 7942 and ∼12 IsiA : Photosystem I in Synechocystis PCC 6803. Concomitantly the iron-rich complexes Cytochrome b6f and Photosystem I declined in abundance, leading to a decrease in the Photosystem I : Photosystem II ratio. Chlorophyll fluorescence analyses showed a drop in electron transport per Photosystem II in Synechococcus, but not in Synechocystis after iron depletion. We found no evidence that the accumulated IsiA contributes to light capture by Photosystem II complexes.
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Affiliation(s)
- Jared M Fraser
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
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35
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Lawrenz E, Silsbe G, Capuzzo E, Ylöstalo P, Forster RM, Simis SGH, Prášil O, Kromkamp JC, Hickman AE, Moore CM, Forget MH, Geider RJ, Suggett DJ. Predicting the electron requirement for carbon fixation in seas and oceans. PLoS One 2013; 8:e58137. [PMID: 23516441 PMCID: PMC3596381 DOI: 10.1371/journal.pone.0058137] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Accepted: 01/30/2013] [Indexed: 11/18/2022] Open
Abstract
Marine phytoplankton account for about 50% of all global net primary productivity (NPP). Active fluorometry, mainly Fast Repetition Rate fluorometry (FRRf), has been advocated as means of providing high resolution estimates of NPP. However, not measuring CO2-fixation directly, FRRf instead provides photosynthetic quantum efficiency estimates from which electron transfer rates (ETR) and ultimately CO2-fixation rates can be derived. Consequently, conversions of ETRs to CO2-fixation requires knowledge of the electron requirement for carbon fixation (Φe,C, ETR/CO2 uptake rate) and its dependence on environmental gradients. Such knowledge is critical for large scale implementation of active fluorescence to better characterise CO2-uptake. Here we examine the variability of experimentally determined Φe,C values in relation to key environmental variables with the aim of developing new working algorithms for the calculation of Φe,C from environmental variables. Coincident FRRf and 14C-uptake and environmental data from 14 studies covering 12 marine regions were analysed via a meta-analytical, non-parametric, multivariate approach. Combining all studies, Φe,C varied between 1.15 and 54.2 mol e− (mol C)−1 with a mean of 10.9±6.91 mol e− mol C)−1. Although variability of Φe,C was related to environmental gradients at global scales, region-specific analyses provided far improved predictive capability. However, use of regional Φe,C algorithms requires objective means of defining regions of interest, which remains challenging. Considering individual studies and specific small-scale regions, temperature, nutrient and light availability were correlated with Φe,C albeit to varying degrees and depending on the study/region and the composition of the extant phytoplankton community. At the level of large biogeographic regions and distinct water masses, Φe,C was related to nutrient availability, chlorophyll, as well as temperature and/or salinity in most regions, while light availability was also important in Baltic Sea and shelf waters. The novel Φe,C algorithms provide a major step forward for widespread fluorometry-based NPP estimates and highlight the need for further studying the natural variability of Φe,C to verify and develop algorithms with improved accuracy.
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Affiliation(s)
- Evelyn Lawrenz
- Laboratory of Photosynthesis, Institute of Microbiology, ASCR (Academy of Sciences of the Czech Republic), Opatovický mlýn, Třeboň, Czech Republic.
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36
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Behrenfeld MJ, Milligan AJ. Photophysiological expressions of iron stress in phytoplankton. ANNUAL REVIEW OF MARINE SCIENCE 2013; 5:217-46. [PMID: 22881354 DOI: 10.1146/annurev-marine-121211-172356] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Iron is essential for all life, but it is particularly important to photoautotrophs because of the many iron-dependent electron transport components in photosynthetic membranes. Since the proliferation of oxygenic photosynthesis in the Archean ocean, iron has been a scarce commodity, and it is now recognized as a limiting resource for phytoplankton over broad expanses of the open ocean and even in some coastal/continental shelf waters. Iron stress does not impair photochemical or carbon fixation efficiencies, and in this respect it resembles the highly tuned photosynthetic systems of steady-state macronutrient-limited phytoplankton. However, iron stress does present unique photophysiological challenges, and phytoplankton have responded to these challenges through major architectural changes in photosynthetic membranes. These evolved responses include overexpression of photosynthetic pigments and iron-economic pathways for ATP synthesis, and they result in diagnostic fluorescence properties that allow a broad appraisal of iron stress in the field and even the detection of iron stress from space.
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Affiliation(s)
- Michael J Behrenfeld
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331-2902, USA.
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37
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Abundances of iron-binding photosynthetic and nitrogen-fixing proteins of Trichodesmium both in culture and in situ from the North Atlantic. PLoS One 2012; 7:e35571. [PMID: 22563465 PMCID: PMC3341377 DOI: 10.1371/journal.pone.0035571] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 03/20/2012] [Indexed: 11/19/2022] Open
Abstract
Marine cyanobacteria of the genus Trichodesmium occur throughout the oligotrophic tropical and subtropical oceans, where they can dominate the diazotrophic community in regions with high inputs of the trace metal iron (Fe). Iron is necessary for the functionality of enzymes involved in the processes of both photosynthesis and nitrogen fixation. We combined laboratory and field-based quantifications of the absolute concentrations of key enzymes involved in both photosynthesis and nitrogen fixation to determine how Trichodesmium allocates resources to these processes. We determined that protein level responses of Trichodesmium to iron-starvation involve down-regulation of the nitrogen fixation apparatus. In contrast, the photosynthetic apparatus is largely maintained, although re-arrangements do occur, including accumulation of the iron-stress-induced chlorophyll-binding protein IsiA. Data from natural populations of Trichodesmium spp. collected in the North Atlantic demonstrated a protein profile similar to iron-starved Trichodesmium in culture, suggestive of acclimation towards a minimal iron requirement even within an oceanic region receiving a high iron-flux. Estimates of cellular metabolic iron requirements are consistent with the availability of this trace metal playing a major role in restricting the biomass and activity of Trichodesmium throughout much of the subtropical ocean.
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