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Reis M, Zenker S, Viehöver P, Niehaus K, Bräutigam A, Eisenhut M. Study of excess manganese stress response highlights the central role of manganese exporter Mnx for holding manganese homeostasis in the cyanobacterium Synechocystis sp. PCC 6803. MICROBIOLOGY (READING, ENGLAND) 2024; 170. [PMID: 39508727 DOI: 10.1099/mic.0.001515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2024]
Abstract
Cellular levels of the essential micronutrient manganese (Mn) need to be carefully balanced within narrow borders. In cyanobacteria, a sufficient Mn supply is critical for ensuring the function of the oxygen-evolving complex as the central part of the photosynthetic machinery. However, Mn accumulation is fatal for the cells. The reason for the observed cytotoxicity is unclear. To understand the causality behind Mn toxicity in cyanobacteria, we investigated the impact of excess Mn on physiology and global gene expression in the model organism Synechocystis sp. PCC 6803. We compared the response of the WT and the knock-out mutant in the Mn exporter (Mnx), ∆mnx, which is disabled in the export of surplus Mn and thus functions as a model for toxic Mn overaccumulation. While growth and pigment accumulation in ∆mnx were severely impaired 24 h after the addition of tenfold Mn, the WT was not affected and thus mounted an adequate transcriptional response. RNA-seq data analysis revealed that the Mn stress transcriptomes partly resembled an iron limitation transcriptome. However, the expression of iron limitation signature genes isiABDC was not affected by the Mn treatment, indicating that Mn excess is not accompanied by iron limitation in Synechocystis. We suggest that the ferric uptake regulator, Fur, gets partially mismetallated under Mn excess conditions and thus interferes with an iron-dependent transcriptional response. To encounter mismetallation and other Mn-dependent problems on a protein level, the cells invest in transcripts of ribosomes, proteases and chaperones. In the case of the ∆mnx mutant, the consequences of the disability to export excess Mn from the cytosol manifest in additionally impaired energy metabolism and oxidative stress transcriptomes with a fatal outcome. This study emphasizes the central importance of Mn homeostasis and the transporter Mnx's role in restoring and holding it.
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Affiliation(s)
- Mara Reis
- Computational Biology, Center for Biotechnology (CeBiTec) and Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Sanja Zenker
- Computational Biology, Center for Biotechnology (CeBiTec) and Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Prisca Viehöver
- Genetics and Genomics of Plants, Center for Biotechnology (CeBiTec) and Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Karsten Niehaus
- Proteome and Metabolome Research, Center for Biotechnology (CeBiTec) and Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Andrea Bräutigam
- Computational Biology, Center for Biotechnology (CeBiTec) and Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Marion Eisenhut
- Computational Biology, Center for Biotechnology (CeBiTec) and Faculty of Biology, Bielefeld University, Bielefeld, Germany
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2
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Mallén-Ponce MJ, Florencio FJ, Huertas MJ. Thioredoxin A regulates protein synthesis to maintain carbon and nitrogen partitioning in cyanobacteria. PLANT PHYSIOLOGY 2024; 195:2921-2936. [PMID: 38386687 PMCID: PMC11288746 DOI: 10.1093/plphys/kiae101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 01/18/2024] [Accepted: 01/19/2024] [Indexed: 02/24/2024]
Abstract
Thioredoxins play an essential role in regulating enzyme activity in response to environmental changes, especially in photosynthetic organisms. They are crucial for metabolic regulation in cyanobacteria, but the key redox-regulated central processes remain to be determined. Physiological, metabolic, and transcriptomic characterization of a conditional mutant of the essential Synechocystis sp. PCC 6803 thioredoxin trxA gene (STXA2) revealed that decreased TrxA levels alter cell morphology and induce a dormant-like state. Furthermore, TrxA depletion in the STXA2 strain inhibited protein synthesis and led to changes in amino acid pools and nitrogen/carbon reserve polymers, accompanied by oxidation of the elongation factor-Tu. Transcriptomic analysis of TrxA depletion in STXA2 revealed a robust transcriptional response. Downregulated genes formed a large cluster directly related to photosynthesis, ATP synthesis, and CO2 fixation. In contrast, upregulated genes were grouped into different clusters related to respiratory electron transport, carotenoid biosynthesis, amino acid metabolism, and protein degradation, among others. These findings highlight the complex regulatory mechanisms that govern cyanobacterial metabolism, where TrxA acts as a critical regulator that orchestrates the transition from anabolic to maintenance metabolism and regulates carbon and nitrogen balance.
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Affiliation(s)
- Manuel J Mallén-Ponce
- Departamento de Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, 41012 Sevilla, Spain
- Instituto de Bioquímica Vegetal y Fotosíntesis (Universidad de Sevilla, Consejo Superior de Investigaciones Científicas), 41092 Sevilla, Spain
| | - Francisco Javier Florencio
- Departamento de Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, 41012 Sevilla, Spain
- Instituto de Bioquímica Vegetal y Fotosíntesis (Universidad de Sevilla, Consejo Superior de Investigaciones Científicas), 41092 Sevilla, Spain
| | - María José Huertas
- Departamento de Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, 41012 Sevilla, Spain
- Instituto de Bioquímica Vegetal y Fotosíntesis (Universidad de Sevilla, Consejo Superior de Investigaciones Científicas), 41092 Sevilla, Spain
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3
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Schiksnis C, Xu M, Saito MA, McIlvin M, Moran D, Bian X, John SG, Zheng Q, Yang N, Fu F, Hutchins DA. Proteomics analysis reveals differential acclimation of coastal and oceanic Synechococcus to climate warming and iron limitation. Front Microbiol 2024; 15:1323499. [PMID: 38444803 PMCID: PMC10912551 DOI: 10.3389/fmicb.2024.1323499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 01/30/2024] [Indexed: 03/07/2024] Open
Abstract
In many oceanic regions, anthropogenic warming will coincide with iron (Fe) limitation. Interactive effects between warming and Fe limitation on phytoplankton physiology and biochemical function are likely, as temperature and Fe availability affect many of the same essential cellular pathways. However, we lack a clear understanding of how globally significant phytoplankton such as the picocyanobacteria Synechococcus will respond to these co-occurring stressors, and what underlying molecular mechanisms will drive this response. Moreover, ecotype-specific adaptations can lead to nuanced differences in responses between strains. In this study, Synechococcus isolates YX04-1 (oceanic) and XM-24 (coastal) from the South China Sea were acclimated to Fe limitation at two temperatures, and their physiological and proteomic responses were compared. Both strains exhibited reduced growth due to warming and Fe limitation. However, coastal XM-24 maintained relatively higher growth rates in response to warming under replete Fe, while its growth was notably more compromised under Fe limitation at both temperatures compared with YX04-1. In response to concurrent heat and Fe stress, oceanic YX04-1 was better able to adjust its photosynthetic proteins and minimize the generation of reactive oxygen species while reducing proteome Fe demand. Its intricate proteomic response likely enabled oceanic YX04-1 to mitigate some of the negative impact of warming on its growth during Fe limitation. Our study highlights how ecologically-shaped adaptations in Synechococcus strains even from proximate oceanic regions can lead to differing physiological and proteomic responses to these climate stressors.
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Affiliation(s)
- Cara Schiksnis
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
| | - Min Xu
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, China
| | - Mak A. Saito
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Matthew McIlvin
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Dawn Moran
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Xiaopeng Bian
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
| | - Seth G. John
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
| | - Qiang Zheng
- State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen, China
| | - Nina Yang
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
- Marine Policy Center, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Feixue Fu
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
| | - David A. Hutchins
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
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4
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Truong A, Myerscough D, Campbell I, Atkinson J, Silberg JJ. A cellular selection identifies elongated flavodoxins that support electron transfer to sulfite reductase. Protein Sci 2023; 32:e4746. [PMID: 37551563 PMCID: PMC10503412 DOI: 10.1002/pro.4746] [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: 03/25/2023] [Revised: 07/17/2023] [Accepted: 08/04/2023] [Indexed: 08/09/2023]
Abstract
Flavodoxins (Flds) mediate the flux of electrons between oxidoreductases in diverse metabolic pathways. To investigate whether Flds can support electron transfer to a sulfite reductase (SIR) that evolved to couple with a ferredoxin, we evaluated the ability of Flds to transfer electrons from a ferredoxin-NADP reductase (FNR) to a ferredoxin-dependent SIR using growth complementation of an Escherichia coli strain with a sulfur metabolism defect. We show that Flds from cyanobacteria complement this growth defect when coexpressed with an FNR and an SIR that evolved to couple with a plant ferredoxin. When we evaluated the effect of peptide insertion on Fld-mediated electron transfer, we observed a sensitivity to insertions within regions predicted to be proximal to the cofactor and partner binding sites, while a high insertion tolerance was detected within loops distal from the cofactor and within regions of helices and sheets that are proximal to those loops. Bioinformatic analysis showed that natural Fld sequence variability predicts a large fraction of the motifs that tolerate insertion of the octapeptide SGRPGSLS. These results represent the first evidence that Flds can support electron transfer to assimilatory SIRs, and they suggest that the pattern of insertion tolerance is influenced by interactions with oxidoreductase partners.
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Affiliation(s)
- Albert Truong
- Biochemistry and Cell Biology Graduate ProgramRice UniversityHoustonTexasUSA
- Department of BiosciencesRice UniversityHoustonTexasUSA
| | | | - Ian Campbell
- Department of BiosciencesRice UniversityHoustonTexasUSA
| | | | - Jonathan J. Silberg
- Department of BiosciencesRice UniversityHoustonTexasUSA
- Department of BioengineeringRice UniversityHoustonTexasUSA
- Department of Chemical and Biomolecular EngineeringRice UniversityHoustonTexasUSA
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5
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Li J, Nie K, Wang L, Zhao Y, Qu M, Yang D, Guan X. The Molecular Mechanism of GhbHLH121 in Response to Iron Deficiency in Cotton Seedlings. PLANTS (BASEL, SWITZERLAND) 2023; 12:1955. [PMID: 37653872 PMCID: PMC10224022 DOI: 10.3390/plants12101955] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/04/2023] [Accepted: 05/08/2023] [Indexed: 09/02/2023]
Abstract
Iron deficiency caused by high pH of saline-alkali soil is a major source of abiotic stress affecting plant growth. However, the molecular mechanism underlying the iron deficiency response in cotton (Gossypium hirsutum) is poorly understood. In this study, we investigated the impacts of iron deficiency at the cotton seedling stage and elucidated the corresponding molecular regulation network, which centered on a hub gene GhbHLH121. Iron deficiency induced the expression of genes with roles in the response to iron deficiency, especially GhbHLH121. The suppression of GhbHLH121 with virus-induced gene silence technology reduced seedlings' tolerance to iron deficiency, with low photosynthetic efficiency and severe damage to the structure of the chloroplast. Contrarily, ectopic expression of GhbHLH121 in Arabidopsis enhanced tolerance to iron deficiency. Further analysis of protein/protein interactions revealed that GhbHLH121 can interact with GhbHLH IVc and GhPYE. In addition, GhbHLH121 can directly activate the expression of GhbHLH38, GhFIT, and GhPYE independent of GhbHLH IVc. All told, GhbHLH121 is a positive regulator of the response to iron deficiency in cotton, directly regulating iron uptake as the upstream gene of GhFIT. Our results provide insight into the complex network of the iron deficiency response in cotton.
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Affiliation(s)
- Jie Li
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Hybrid Cotton R & D Engineering Research Center (the Ministry of Education), College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China;
- Zhejiang Provincial Key Laboratory of Crop Genetic Resources, Institute of Crop Science, Plant Precision Breeding Academy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 300058, China; (K.N.); (L.W.); (Y.Z.)
| | - Ke Nie
- Zhejiang Provincial Key Laboratory of Crop Genetic Resources, Institute of Crop Science, Plant Precision Breeding Academy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 300058, China; (K.N.); (L.W.); (Y.Z.)
- Hainan Institute, Zhejiang University, Yongyou Industry Park, Yazhou Bay Sci-Tech City, Sanya 572000, China
| | - Luyao Wang
- Zhejiang Provincial Key Laboratory of Crop Genetic Resources, Institute of Crop Science, Plant Precision Breeding Academy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 300058, China; (K.N.); (L.W.); (Y.Z.)
- Hainan Institute, Zhejiang University, Yongyou Industry Park, Yazhou Bay Sci-Tech City, Sanya 572000, China
| | - Yongyan Zhao
- Zhejiang Provincial Key Laboratory of Crop Genetic Resources, Institute of Crop Science, Plant Precision Breeding Academy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 300058, China; (K.N.); (L.W.); (Y.Z.)
| | - Mingnan Qu
- Hainan Yazhou Bay Seed Lab, Yazhou Bay Science and Technology City, Yazhou District, Sanya 572025, China;
| | - Donglei Yang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Hybrid Cotton R & D Engineering Research Center (the Ministry of Education), College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China;
| | - Xueying Guan
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Hybrid Cotton R & D Engineering Research Center (the Ministry of Education), College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China;
- Zhejiang Provincial Key Laboratory of Crop Genetic Resources, Institute of Crop Science, Plant Precision Breeding Academy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 300058, China; (K.N.); (L.W.); (Y.Z.)
- Hainan Institute, Zhejiang University, Yongyou Industry Park, Yazhou Bay Sci-Tech City, Sanya 572000, China
- Hainan Yazhou Bay Seed Lab, Yazhou Bay Science and Technology City, Yazhou District, Sanya 572025, China;
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6
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Wang Y, Ge H, Xiao Z, Huang C, Wang G, Duan X, Zheng L, Dong J, Huang X, Zhang Y, An H, Xu W, Wang Y. Spatial Proteome Reorganization of a Photosynthetic Model Cyanobacterium in Response to Abiotic Stresses. J Proteome Res 2023; 22:1255-1269. [PMID: 36930737 DOI: 10.1021/acs.jproteome.2c00759] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
Abstract
Spatial proteome reorganization in response to a changing environment represents a different layer of adaptation mechanism in addition to differential expression of a subset of stress responsive genes in photosynthetic organisms. Profiling such reorganization events is critically important to extend our understanding how photosynthetic organisms adapt to adverse environments. Thus, we treated a unicellular photosynthetic model cyanobacterium, Synechocystis sp. PCC 6803 (hereafter referred to as Synechocystis), with five different types of abiotic stresses including nitrogen starvation, iron deficiency, cold, heat, and darkness, and systematically identified proteins showing stress-induced differential expression and/or redistribution between the membrane and the soluble fractions using a quantitative proteomics approach. A number of proteins showing such a redistribution in response to a single or multiple types of abiotic stresses were identified. These include 12 ribosomal proteins displaying unanimous cold-induced redistribution to the membrane and the protein FurA, a master regulator of iron acquisition, displaying iron deficiency- and nitrogen starvation-induced redistribution to the membrane. Such findings shed light on a novel regulatory mechanism underlying the corresponding stress responses, and establish the results in the present study as an important resource for future studies intended to understand how photosynthetic organisms cope with adverse environments.
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Affiliation(s)
- Yan Wang
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Huairou District, Beijing 101408, China
| | - Haitao Ge
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China
| | - Zhen Xiao
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Huairou District, Beijing 101408, China
| | - Chengcheng Huang
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Huairou District, Beijing 101408, China
| | - Gaojie Wang
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Huairou District, Beijing 101408, China
| | - Xiaoxiao Duan
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Huairou District, Beijing 101408, China
| | - Limin Zheng
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Huairou District, Beijing 101408, China
| | - Jinghui Dong
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Huairou District, Beijing 101408, China
| | - Xiahe Huang
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China
| | - Yuanya Zhang
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China
| | - Hongyu An
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Huairou District, Beijing 101408, China
| | - Wu Xu
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Innovation Academy for Seed Design, CAS, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Huairou District, Beijing 101408, China
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7
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Zhao LS, Li CY, Chen XL, Wang Q, Zhang YZ, Liu LN. Native architecture and acclimation of photosynthetic membranes in a fast-growing cyanobacterium. PLANT PHYSIOLOGY 2022; 190:1883-1895. [PMID: 35947692 PMCID: PMC9614513 DOI: 10.1093/plphys/kiac372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
Efficient solar energy conversion is ensured by the organization, physical association, and physiological coordination of various protein complexes in photosynthetic membranes. Here, we visualize the native architecture and interactions of photosynthetic complexes within the thylakoid membranes from a fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 (Syn2973) using high-resolution atomic force microscopy. In the Syn2973 thylakoid membranes, both photosystem I (PSI)-enriched domains and crystalline photosystem II (PSII) dimer arrays were observed, providing favorable membrane environments for photosynthetic electron transport. The high light (HL)-adapted thylakoid membranes accommodated a large amount of PSI complexes, without the incorporation of iron-stress-induced protein A (IsiA) assemblies and formation of IsiA-PSI supercomplexes. In the iron deficiency (Fe-)-treated thylakoid membranes, in contrast, IsiA proteins densely associated with PSI, forming the IsiA-PSI supercomplexes with varying assembly structures. Moreover, type-I NADH dehydrogenase-like complexes (NDH-1) were upregulated under the HL and Fe- conditions and established close association with PSI complexes to facilitate cyclic electron transport. Our study provides insight into the structural heterogeneity and plasticity of the photosynthetic apparatus in the context of their native membranes in Syn2973 under environmental stress. Advanced understanding of the photosynthetic membrane organization and adaptation will provide a framework for uncovering the molecular mechanisms of efficient light harvesting and energy conversion.
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Affiliation(s)
| | - Chun-Yang Li
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao 266237, China
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Xiu-Lan Chen
- State Key Laboratory of Microbial Technology, and Marine Biotechnology Research Center, Shandong University, Qingdao 266237, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Qiang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China
- Academy for Advanced Interdisciplinary Studies, Henan University, 475004 Kaifeng, China
| | - Yu-Zhong Zhang
- State Key Laboratory of Microbial Technology, and Marine Biotechnology Research Center, Shandong University, Qingdao 266237, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao 266237, China
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Lu-Ning Liu
- Author of correspondence: (L.-N.L.), (L.-S.Z.)
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8
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Gilbert NE, LeCleir GR, Strzepek RF, Ellwood MJ, Twining BS, Roux S, Pennacchio C, Boyd PW, Wilhelm SW. Bioavailable iron titrations reveal oceanic Synechococcus ecotypes optimized for different iron availabilities. ISME COMMUNICATIONS 2022; 2:54. [PMID: 37938659 PMCID: PMC9723758 DOI: 10.1038/s43705-022-00132-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/24/2022] [Accepted: 06/09/2022] [Indexed: 04/18/2023]
Abstract
The trace metal iron (Fe) controls the diversity and activity of phytoplankton across the surface oceans, a paradigm established through decades of in situ and mesocosm experimental studies. Despite widespread Fe-limitation within high-nutrient, low chlorophyll (HNLC) waters, significant contributions of the cyanobacterium Synechococcus to the phytoplankton stock can be found. Correlations among differing strains of Synechococcus across different Fe-regimes have suggested the existence of Fe-adapted ecotypes. However, experimental evidence of high- versus low-Fe adapted strains of Synechococcus is lacking, and so we investigated the transcriptional responses of microbial communities inhabiting the HNLC, sub-Antarctic region of the Southern Ocean during the Spring of 2018. Analysis of metatranscriptomes generated from on-deck incubation experiments reflecting a gradient of Fe-availabilities reveal transcriptomic signatures indicative of co-occurring Synechococcus ecotypes adapted to differing Fe-regimes. Functional analyses comparing low-Fe and high-Fe conditions point to various Fe-acquisition mechanisms that may allow persistence of low-Fe adapted Synechococcus under Fe-limitation. Comparison of in situ surface conditions to the Fe-titrations indicate ecological relevance of these mechanisms as well as persistence of both putative ecotypes within this region. This Fe-titration approach, combined with transcriptomics, highlights the short-term responses of the in situ phytoplankton community to Fe-availability that are often overlooked by examining genomic content or bulk physiological responses alone. These findings expand our knowledge about how phytoplankton in HNLC Southern Ocean waters adapt and respond to changing Fe supply.
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Affiliation(s)
- Naomi E Gilbert
- Department of Microbiology, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Gary R LeCleir
- Department of Microbiology, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Robert F Strzepek
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, 7004, Australia
- Australian Antarctic Program Partnership (AAPP), Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, 7004, Australia
| | - Michael J Ellwood
- Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia
| | | | - S Roux
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - C Pennacchio
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Philip W Boyd
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, 7004, Australia
| | - Steven W Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, TN, 37996, USA.
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9
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Homologs of Phycobilisome Abundance Regulator PsoR Are Widespread across Cyanobacteria. MICROBIOLOGY RESEARCH 2022. [DOI: 10.3390/microbiolres13020014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
During chromatic acclimation (CA), cyanobacteria undergo shifts in their physiology and metabolism in response to changes in their light environment. Various forms of CA, which involves the tuning of light-harvesting accessory complexes known as phycobilisomes (PBS) in response to distinct wavelengths of light, have been recognized. Recently, a negative regulator of PBS abundance, PsoR, about which little was known, was identified. We used sequence analyses and bioinformatics to predict the role of PsoR in cyanobacteria and PBS regulation and to examine its presence in a diverse range of cyanobacteria. PsoR has sequence similarities to the β-CASP family of proteins involved in DNA and RNA processing. PsoR is a putative nuclease widespread across Cyanobacteria, of which over 700 homologs have been observed. Promoter analysis suggested that psoR is co-transcribed with upstream gene tcpA. Multiple transcription factors involved in global gene regulation and stress responses were predicted to bind to the psoR-tcpA promoter. The predicted protein–protein interactions with PsoR homologs included proteins involved in DNA and RNA metabolism, as well as a phycocyanin-associated protein predicted to interact with PsoR from Fremyella diplosiphon (FdPsoR). The widespread presence of PsoR homologs in Cyanobacteria and their ties to DNA- and RNA-metabolizing proteins indicated a potentially unique role for PsoR in CA and PBS abundance regulation.
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10
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Riediger M, Hernández-Prieto MA, Song K, Hess WR, Futschik ME. Genome-wide identification and characterization of Fur-binding sites in the cyanobacteria Synechocystis sp. PCC 6803 and PCC 6714. DNA Res 2021; 28:6407143. [PMID: 34672328 PMCID: PMC8634477 DOI: 10.1093/dnares/dsab023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 10/16/2021] [Indexed: 11/16/2022] Open
Abstract
The Ferric uptake regulator (Fur) is crucial to both pathogenic and non-pathogenic bacteria for the maintenance of iron homeostasis as well as the defence against reactive oxygen species. Based on datasets from the genome-wide mapping of transcriptional start sites and transcriptome data, we identified a high confidence regulon controlled by Fur for the model cyanobacterium Synechocystis sp. PCC 6803 and its close relative, strain 6714, based on the conserved strong iron starvation response and Fur-binding site occurrence. This regulon comprises 33 protein-coding genes and the sRNA IsaR1 that are under the control of 16 or 14 individual promoters in strains 6803 and 6714, respectively. The associated gene functions are mostly restricted to transporters and enzymes involved in the uptake and storage of iron ions, with few exceptions or unknown functional relevance. Within the isiABC operon, we identified a previously neglected gene encoding a small cysteine-rich protein, which we suggest calling, IsiE. The regulation of iron uptake, storage, and utilization ultimately results from the interplay between the Fur regulon, several other transcription factors, the FtsH3 protease, and the sRNA IsaR1.
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Affiliation(s)
- Matthias Riediger
- Institute of Biology III, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Miguel A Hernández-Prieto
- ARC Centre of Excellence for Translational Photosynthesis & School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
| | - Kuo Song
- Institute of Biology III, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Wolfgang R Hess
- Institute of Biology III, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Matthias E Futschik
- SysBioLab, Centre of Marine Sciences (CCMAR), University of Algarve, 8005-139 Faro, Portugal.,MRC London Institute of Medical Sciences (LMS), Faculty of Medicine, Imperial College London, London W12 0NN, UK
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11
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Zhen ZH, Qin S, Ren QM, Wang Y, Ma YY, Wang YC. Reciprocal Effect of Copper and Iron Regulation on the Proteome of Synechocystis sp. PCC 6803. Front Bioeng Biotechnol 2021; 9:673402. [PMID: 34041232 PMCID: PMC8141849 DOI: 10.3389/fbioe.2021.673402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 04/14/2021] [Indexed: 11/13/2022] Open
Abstract
Cyanobacteria can acclimate to changing copper and iron concentrations in the environment via metal homeostasis, but a general mechanism for interpreting their dynamic relationships is sparse. In this study, we assessed growth and chlorophyll fluorescence of Synechocystis sp. PCC 6803 and investigated proteomic responses to copper and iron deductions. Results showed that copper and iron exerted reciprocal effect on the growth and photosynthesis of Synechocystis sp. PCC 6803 at combinations of different concentrations. And some proteins involved in the uptake of copper and iron and the photosynthetic electron transport system exhibit Cu-Fe proteomic association. The protein abundance under copper and iron deduction affected the photosynthetic electronic activity of Synechocystis sp. PCC 6803 and eventually affected the growth and photosynthesis. Based on these results, we hypothesize that the Cu-Fe proteomic association of Synechocystis sp. PCC 6803 can be elucidated via the uptake system of outer membrane-periplasmic space-inner plasma membrane-thylakoid membrane, and this association is mainly required to maintain electron transfer. This study provides a broader view regarding the proteomic association between Cu and Fe in cyanobacteria, which will shed light on the role of these two metal elements in cyanobacterial energy metabolism and biomass accumulation.
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Affiliation(s)
- Zhang-He Zhen
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Song Qin
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Qing-Min Ren
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yu Wang
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Yu-Ying Ma
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Yin-Chu Wang
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
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12
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Sangphukieo A, Laomettachit T, Ruengjitchatchawalya M. PhotoModPlus: A web server for photosynthetic protein prediction from genome neighborhood features. PLoS One 2021; 16:e0248682. [PMID: 33730083 PMCID: PMC7968678 DOI: 10.1371/journal.pone.0248682] [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: 06/15/2020] [Accepted: 03/03/2021] [Indexed: 11/20/2022] Open
Abstract
A new web server called PhotoModPlus is presented as a platform for predicting photosynthetic proteins via genome neighborhood networks (GNN) and genome neighborhood-based machine learning. GNN enables users to visualize the overview of the conserved neighboring genes from multiple photosynthetic prokaryotic genomes and provides functional guidance on the query input. In the platform, we also present a new machine learning model utilizing genome neighborhood features for predicting photosynthesis-specific functions based on 24 prokaryotic photosynthesis-related GO terms, namely PhotoModGO. The new model performed better than the sequence-based approaches with an F1 measure of 0.872, based on nested five-fold cross-validation. Finally, we demonstrated the applications of the webserver and the new model in the identification of novel photosynthetic proteins. The server is user-friendly, compatible with all devices, and available at bicep.kmutt.ac.th/photomod.
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Affiliation(s)
- Apiwat Sangphukieo
- Bioinformatics and Systems Biology Program, School of Bioresources and Technology, King Mongkut’s University of Technology Thonburi (KMUTT), Bang Khun Thian, Bangkok, Thailand
- School of Information Technology, KMUTT, Thung Khru, Bangkok, Thailand
| | - Teeraphan Laomettachit
- Bioinformatics and Systems Biology Program, School of Bioresources and Technology, King Mongkut’s University of Technology Thonburi (KMUTT), Bang Khun Thian, Bangkok, Thailand
| | - Marasri Ruengjitchatchawalya
- Bioinformatics and Systems Biology Program, School of Bioresources and Technology, King Mongkut’s University of Technology Thonburi (KMUTT), Bang Khun Thian, Bangkok, Thailand
- Biotechnology Program, School of Bioresources and Technology, KMUTT, Bang Khun Thian, Bangkok, Thailand
- Algal Biotechnology Research Group, Pilot Plant Development and Training Institute, KMUTT, Bang Khun Thian, Bangkok, Thailand
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13
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Chu F, Cheng J, Hou W, Yang W, Zhang P, Park JY, Kim H, Xu L. Fecitrate converted from Fe 2O 3 particles in coal-fired flue gas promoted microalgal biomass and lipid productivities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 760:143405. [PMID: 33199017 DOI: 10.1016/j.scitotenv.2020.143405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/27/2020] [Accepted: 10/27/2020] [Indexed: 06/11/2023]
Abstract
In order to reutilize Fe2O3 particles in flue gas from coal-fired power plant as a ferrum nutrient for improving microalgae growth, Na-Citrate was proposed to chelate FeCl3 derived from Fe2O3 and HCl reactions to promote biomass and lipid productivities of Chlorella PY-ZU1. Fe-Citrate gave much higher biomass and lipid productivities than FeCl3, Fe-EDTA, Fe-DTPA and Fe-HEDTA, because organic chelator prevented Fe3+ from depositing, lower stability constant resulted in easier dissociation of ferric chelate, smaller chelate facilitated Fe2+ (reduced from Fe3+) transportation through cell membranes. The biomass growth and photosynthetic capacity of Chlorella PY-ZU1 cultivated with Fe-Citrate (converted from Fe2O3 particles) medium were similar to those with commercial ferric ammonium citrate medium. The biomass and lipid productivities of Chlorella PY-ZU1 cultivated with 5 mg L-1 Fe-Citrate medium were 1.30 and 1.72 times, respectively, higher than those with FeCl3 growth medium.
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Affiliation(s)
- Feifei Chu
- College of Standardization, China Jiliang University, Hangzhou 310018, China
| | - Jun Cheng
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China.
| | - Wen Hou
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Weijuan Yang
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Pengyue Zhang
- College of Standardization, China Jiliang University, Hangzhou 310018, China
| | - Ji-Yeon Park
- Biomass and Wastes to Energy Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Daejeon 34129, Republic of Korea
| | - Hyungtaek Kim
- Division of Energy Systems Research, Ajou University, Suwon, Republic of Korea
| | - Lihua Xu
- Division of Energy Systems Research, Ajou University, Suwon, Republic of Korea
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14
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Qiu GW, Lis H, Qiu BS, Keren N. Long-term iron deprivation and subsequent recovery uncover heterogeneity in the response of cyanobacterial populations. Environ Microbiol 2021; 23:1793-1804. [PMID: 33615658 DOI: 10.1111/1462-2920.15443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/15/2021] [Accepted: 02/20/2021] [Indexed: 11/29/2022]
Abstract
Cyanobacteria are globally important primary producers and nitrogen fixers. They are frequently limited by iron bioavailability in natural environments that often fluctuate due to rapid consumption and irregular influx of external Fe. Here we identify a succession of physiological changes in Synechocystis sp. PCC 6803 occurring over 14-16 days of iron deprivation and subsequent recovery. We observe several adaptive strategies that allow cells to push their metabolic limits under the restriction of declining intracellular Fe quotas. Interestingly, cyanobacterial populations exposed to prolonged iron deprivation showed discernible heterogeneity in cellular auto-fluorescence during the recovery process. Using FACS and microscopy techniques we revealed that only cells with high auto-fluorescence were able to grow and reconstitute thylakoid membranes. We propose that ROS-mediated damage is likely to be associated with the emergence of the two subpopulations, and, indeed, a rapid increase in intracellular ROS content was observed during the first hours following iron addition to Fe-starved cultures. These results suggest that an increasing iron supply is a double-edged sword - posing both an opportunity and a risk. Therefore, phenotypic heterogeneity within populations is crucial for the survival and proliferation of organisms facing iron fluctuations within natural environments.
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Affiliation(s)
- Guo-Wei Qiu
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, 9190402, Israel.,School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Hagar Lis
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, 9190402, Israel
| | - Bao-Sheng Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - 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, 9190402, Israel
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15
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Hunnestad AV, Vogel AIM, Armstrong E, Digernes MG, Ardelan MV, Hohmann-Marriott MF. From the Ocean to the Lab-Assessing Iron Limitation in Cyanobacteria: An Interface Paper. Microorganisms 2020; 8:E1889. [PMID: 33260337 PMCID: PMC7760322 DOI: 10.3390/microorganisms8121889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/25/2020] [Accepted: 11/26/2020] [Indexed: 12/22/2022] Open
Abstract
Iron is an essential, yet scarce, nutrient in marine environments. Phytoplankton, and especially cyanobacteria, have developed a wide range of mechanisms to acquire iron and maintain their iron-rich photosynthetic machinery. Iron limitation studies often utilize either oceanographic methods to understand large scale processes, or laboratory-based, molecular experiments to identify underlying molecular mechanisms on a cellular level. Here, we aim to highlight the benefits of both approaches to encourage interdisciplinary understanding of the effects of iron limitation on cyanobacteria with a focus on avoiding pitfalls in the initial phases of collaboration. In particular, we discuss the use of trace metal clean methods in combination with sterile techniques, and the challenges faced when a new collaboration is set up to combine interdisciplinary techniques. Methods necessary for producing reliable data, such as High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS), Flow Injection Analysis Chemiluminescence (FIA-CL), and 77K fluorescence emission spectroscopy are discussed and evaluated and a technical manual, including the preparation of the artificial seawater medium Aquil, cleaning procedures, and a sampling scheme for an iron limitation experiment is included. This paper provides a reference point for researchers to implement different techniques into interdisciplinary iron studies that span cyanobacteria physiology, molecular biology, and biogeochemistry.
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Affiliation(s)
- Annie Vera Hunnestad
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.V.H.); (M.G.D.)
| | - Anne Ilse Maria Vogel
- PhotoSynLab, Department of Biotechnology and Food Science, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.I.M.V.); (M.F.H.-M.)
| | - Evelyn Armstrong
- NIWA/University of Otago Research Centre for Oceanography, Department of Chemistry, University of Otago, 9054 Dunedin, New Zealand;
| | - Maria Guadalupe Digernes
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.V.H.); (M.G.D.)
| | - Murat Van Ardelan
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.V.H.); (M.G.D.)
| | - Martin Frank Hohmann-Marriott
- PhotoSynLab, Department of Biotechnology and Food Science, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.I.M.V.); (M.F.H.-M.)
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16
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Guyet U, Nguyen NA, Doré H, Haguait J, Pittera J, Conan M, Ratin M, Corre E, Le Corguillé G, Brillet-Guéguen L, Hoebeke M, Six C, Steglich C, Siegel A, Eveillard D, Partensky F, Garczarek L. Synergic Effects of Temperature and Irradiance on the Physiology of the Marine Synechococcus Strain WH7803. Front Microbiol 2020; 11:1707. [PMID: 32793165 PMCID: PMC7393227 DOI: 10.3389/fmicb.2020.01707] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/29/2020] [Indexed: 11/18/2022] Open
Abstract
Understanding how microorganisms adjust their metabolism to maintain their ability to cope with short-term environmental variations constitutes one of the major current challenges in microbial ecology. Here, the best physiologically characterized marine Synechococcus strain, WH7803, was exposed to modulated light/dark cycles or acclimated to continuous high-light (HL) or low-light (LL), then shifted to various stress conditions, including low (LT) or high temperature (HT), HL and ultraviolet (UV) radiations. Physiological responses were analyzed by measuring time courses of photosystem (PS) II quantum yield, PSII repair rate, pigment ratios and global changes in gene expression. Previously published membrane lipid composition were also used for correlation analyses. These data revealed that cells previously acclimated to HL are better prepared than LL-acclimated cells to sustain an additional light or UV stress, but not a LT stress. Indeed, LT seems to induce a synergic effect with the HL treatment, as previously observed with oxidative stress. While all tested shift conditions induced the downregulation of many photosynthetic genes, notably those encoding PSI, cytochrome b6/f and phycobilisomes, UV stress proved to be more deleterious for PSII than the other treatments, and full recovery of damaged PSII from UV stress seemed to involve the neo-synthesis of a fairly large number of PSII subunits and not just the reassembly of pre-existing subunits after D1 replacement. In contrast, genes involved in glycogen degradation and carotenoid biosynthesis pathways were more particularly upregulated in response to LT. Altogether, these experiments allowed us to identify responses common to all stresses and those more specific to a given stress, thus highlighting genes potentially involved in niche acclimation of a key member of marine ecosystems. Our data also revealed important specific features of the stress responses compared to model freshwater cyanobacteria.
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Affiliation(s)
- Ulysse Guyet
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Ngoc A Nguyen
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Hugo Doré
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Julie Haguait
- LS2N, UMR CNRS 6004, IMT Atlantique, ECN, Université de Nantes, Nantes, France
| | - Justine Pittera
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Maël Conan
- DYLISS (INRIA-IRISA)-INRIA, CNRS UMR 6074, Université de Rennes 1, Rennes, France
| | - Morgane Ratin
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Erwan Corre
- CNRS, FR2424, ABiMS, Station Biologique, Sorbonne Université, Roscoff, France
| | - Gildas Le Corguillé
- CNRS, FR2424, ABiMS, Station Biologique, Sorbonne Université, Roscoff, France
| | - Loraine Brillet-Guéguen
- CNRS, FR2424, ABiMS, Station Biologique, Sorbonne Université, Roscoff, France.,CNRS, UMR 8227 Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Mark Hoebeke
- CNRS, FR2424, ABiMS, Station Biologique, Sorbonne Université, Roscoff, France
| | - Christophe Six
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | | | - Anne Siegel
- DYLISS (INRIA-IRISA)-INRIA, CNRS UMR 6074, Université de Rennes 1, Rennes, France
| | - Damien Eveillard
- LS2N, UMR CNRS 6004, IMT Atlantique, ECN, Université de Nantes, Nantes, France
| | - Frédéric Partensky
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Laurence Garczarek
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
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17
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FurA-Dependent Microcystin Synthesis under Copper Stress in Microcystis aeruginosa. Microorganisms 2020; 8:microorganisms8060832. [PMID: 32492911 PMCID: PMC7356878 DOI: 10.3390/microorganisms8060832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/19/2020] [Accepted: 05/19/2020] [Indexed: 11/17/2022] Open
Abstract
Massive blooms of cyanobacteria frequently occur with microcystin (MC) production. Cyanobacteria are exposed to copper stresses such as copper algaecides which are often used to remove cyanobacterial blooms. However, copper increased the MC production of cyanobacteria, and the underlying mechanism remains unclear. The present study investigated the relationship between copper exposure (0.5 and 3 µM) and MC synthesis in Microcystis aeruginosa PCC 7806. The study concluded that the content of intracellular MCs increased by nearly two times both in 0.5 and 3 µM copper. High-throughput RNA sequencing (RNA-seq) provided evidence that copper mainly attacked Fe-S clusters, with evidence of changes in iron, sulfur, iron uptake regulators (fur), glutaredoxins and dehydratase genes. The transcription of numbers of genes implicated in iron uptake, MC synthesis and furA was also evaluated with quantitative real-time PCR (qRT-PCR). In these three Cu treatment groups, the amount of MCs increased as copper elevated. As the expression of mcyD gene was directly regulated by FurA and copper ions affected the expression of the FurA-related genes, we believed that MC synthesis genes were controlled by copper. This study has made a further understanding of the mechanism of the increase in MC synthesis of M. aeruginosa PCC 7806 treated with copper-based algaecides. We aimed to understand the mechanism of copper ion influencing the synthesis of MCs.
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18
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Kroh GE, Pilon M. Regulation of Iron Homeostasis and Use in Chloroplasts. Int J Mol Sci 2020; 21:E3395. [PMID: 32403383 PMCID: PMC7247011 DOI: 10.3390/ijms21093395] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/08/2020] [Accepted: 05/09/2020] [Indexed: 01/20/2023] Open
Abstract
Iron (Fe) is essential for life because of its role in protein cofactors. Photosynthesis, in particular photosynthetic electron transport, has a very high demand for Fe cofactors. Fe is commonly limiting in the environment, and therefore photosynthetic organisms must acclimate to Fe availability and avoid stress associated with Fe deficiency. In plants, adjustment of metabolism, of Fe utilization, and gene expression, is especially important in the chloroplasts during Fe limitation. In this review, we discuss Fe use, Fe transport, and mechanisms of acclimation to Fe limitation in photosynthetic lineages with a focus on the photosynthetic electron transport chain. We compare Fe homeostasis in Cyanobacteria, the evolutionary ancestors of chloroplasts, with Fe homeostasis in green algae and in land plants in order to provide a deeper understanding of how chloroplasts and photosynthesis may cope with Fe limitation.
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Affiliation(s)
| | - Marinus Pilon
- Department of Biology, Colorado State University Department of Biology, Fort Collins, CO 80523, USA;
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19
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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: 49] [Impact Index Per Article: 12.3] [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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20
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Polyviou D, Machelett MM, Hitchcock A, Baylay AJ, MacMillan F, Moore CM, Bibby TS, Tews I. Structural and functional characterization of IdiA/FutA (Tery_3377), an iron-binding protein from the ocean diazotroph Trichodesmium erythraeum. J Biol Chem 2018; 293:18099-18109. [PMID: 30217820 PMCID: PMC6254336 DOI: 10.1074/jbc.ra118.001929] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 08/31/2018] [Indexed: 11/17/2022] Open
Abstract
Atmospheric nitrogen fixation by photosynthetic cyanobacteria (diazotrophs) strongly influences oceanic primary production and in turn affects global biogeochemical cycles. Species of the genus Trichodesmium are major contributors to marine diazotrophy, accounting for a significant proportion of the fixed nitrogen in tropical and subtropical oceans. However, Trichodesmium spp. are metabolically constrained by the availability of iron, an essential element for both the photosynthetic apparatus and the nitrogenase enzyme. Survival strategies in low-iron environments are typically poorly characterized at the molecular level, because these bacteria are recalcitrant to genetic manipulation. Here, we studied a homolog of the iron deficiency-induced A (IdiA)/ferric uptake transporter A (FutA) protein, Tery_3377, which has been used as an in situ iron-stress biomarker. IdiA/FutA has an ambiguous function in cyanobacteria, with its homologs hypothesized to be involved in distinct processes depending on their cellular localization. Using signal sequence fusions to GFP and heterologous expression in the model cyanobacterium Synechocystis sp. PCC 6803, we show that Tery_3377 is targeted to the periplasm by the twin-arginine translocase and can complement the deletion of the native Synechocystis ferric-iron ABC transporter periplasmic binding protein (FutA2). EPR spectroscopy revealed that purified recombinant Tery_3377 has specificity for iron in the Fe3+ state, and an X-ray crystallography–determined structure uncovered a functional iron substrate–binding domain, with Fe3+ pentacoordinated by protein and buffer ligands. Our results support assignment of Tery_3377 as a functional FutA subunit of an Fe3+ ABC transporter but do not rule out dual IdiA function.
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Affiliation(s)
- Despo Polyviou
- From the Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, United Kingdom
| | - Moritz M Machelett
- From the Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, United Kingdom,; the Department of Biological Sciences, Faculty of Natural and Environmental Sciences, Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom, and
| | - Andrew Hitchcock
- From the Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, United Kingdom
| | - Alison J Baylay
- From the Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, United Kingdom
| | - Fraser MacMillan
- the School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - C Mark Moore
- From the Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, United Kingdom
| | - Thomas S Bibby
- From the Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, United Kingdom
| | - Ivo Tews
- the Department of Biological Sciences, Faculty of Natural and Environmental Sciences, Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom, and.
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Wang YX, Hu Y, Zhu YF, Baloch AW, Jia XM, Guo AX. Transcriptional and physiological analyses of short-term Iron deficiency response in apple seedlings provide insight into the regulation involved in photosynthesis. BMC Genomics 2018; 19:461. [PMID: 29902966 PMCID: PMC6003109 DOI: 10.1186/s12864-018-4846-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 05/31/2018] [Indexed: 12/29/2022] Open
Abstract
Background Iron (Fe) is an essential micronutrient for plants. Utilization of Fe deficiency-tolerant rootstock is an effective strategy to prevent Fe deficiency problems in fruit trees production. Malus halliana is an apple rootstock that is resistant to Fe deficiency; however, few molecular studies have been conducted on M. halliana. Results To evaluate short-term molecular response of M. halliana leaves under Fe deficiency condition, RNA sequencing (RNA-Seq) analyses were conducted at 0 (T1), 0.5 (T2) and 3 d (T3) after Fe-deficiency stress, and the timepoints were determined with a preliminary physiological experiment. In all, 6907, 5328, and 3593 differentially expressed genes (DEGs) were identified in pairs of T2 vs. T1, T3 vs. T1, and T3 vs. T2. Several of the enriched DEGs were related to heme binding, Fe ion binding, thylakoid membranes, photosystem II, photosynthesis-antenna protein, porphyrin and chlorophyll metabolism and carotenoid biosynthesis under Fe deficiency, which suggests that Fe deficiency mainly affects the photosynthesis of M. halliana. Additionally, we found that Fe deficiency induced significant down-regulation in genes involved in photosynthesis at T2 when seedlings were treated with Fe-deficient solution for 0.5 d, indicating that there was a rapid response of M. halliana to Fe deficiency. A strong up-regulation of photosynthesis genes was detected at T3, which suggested that M. halliana was able to recover photosynthesis after prolonged Fe starvation. A similar expression pattern was found in pigment regulation, including genes for coding chlorophyllide a oxygenase (CAO), β-carotene hydroxylase (β-OHase), zeaxanthin epoxidase (ZEP) and 9-cis-epoxycarotenoid dioxygenase (NCED). Our results suggest that pigment regulation plays an important role in the Fe deficiency response. In addition, we verified sixteen genes related to photosynthesis-antenna protein, porphyrin and chlorophyll metabolism and carotenoid biosynthesis pathways using quantitative real-time PCR (qRT-PCR) to ensure the accuracy of transcriptome data. Photosynthetic parameters, Chl fluorescence parameters and the activity of Chlase were also determined. Conclusions This study broadly characterizes a molecular mechanism in which pigment and photosynthesis-related regulations play indispensable roles in the response of M. halliana to short-term Fe deficiency and provides a basis for future analyses of the key genes involved in the tolerance of Fe deficiency. Electronic supplementary material The online version of this article (10.1186/s12864-018-4846-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yan-Xiu Wang
- College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu, China.
| | - Ya Hu
- College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Yan-Fang Zhu
- College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Abdul Wahid Baloch
- Department of Plant Breeding & Genetics, Faculty of Crop Production, Sindh Agriculture University, Tandojam, Pakistan
| | - Xu-Mei Jia
- College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Ai-Xia Guo
- College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu, China
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Obando S. TA, Babykin MM, Zinchenko VV. A Cluster of Five Genes Essential for the Utilization of Dihydroxamate Xenosiderophores in Synechocystis sp. PCC 6803. Curr Microbiol 2018; 75:1165-1173. [DOI: 10.1007/s00284-018-1505-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/03/2018] [Indexed: 10/16/2022]
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23
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Pierella Karlusich JJ, Carrillo N. Evolution of the acceptor side of photosystem I: ferredoxin, flavodoxin, and ferredoxin-NADP + oxidoreductase. PHOTOSYNTHESIS RESEARCH 2017; 134:235-250. [PMID: 28150152 DOI: 10.1007/s11120-017-0338-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/12/2017] [Indexed: 05/21/2023]
Abstract
The development of oxygenic photosynthesis by primordial cyanobacteria ~2.7 billion years ago led to major changes in the components and organization of photosynthetic electron transport to cope with the challenges of an oxygen-enriched atmosphere. We review herein, following the seminal contributions as reported by Jaganathan et al. (Functional genomics and evolution of photosynthetic systems, vol 33, advances in photosynthesis and respiration, Springer, Dordrecht, 2012), how these changes affected carriers and enzymes at the acceptor side of photosystem I (PSI): the electron shuttle ferredoxin (Fd), its isofunctional counterpart flavodoxin (Fld), their redox partner ferredoxin-NADP+ reductase (FNR), and the primary PSI acceptors F x and F A/F B. Protection of the [4Fe-4S] centers of these proteins from oxidative damage was achieved by strengthening binding between the F A/F B polypeptide and the reaction center core containing F x, therefore impairing O2 access to the clusters. Immobilization of F A/F B in the PSI complex led in turn to the recruitment of new soluble electron shuttles. This function was fulfilled by oxygen-insensitive [2Fe-2S] Fd, in which the reactive sulfide atoms of the cluster are shielded from solvent by the polypeptide backbone, and in some algae and cyanobacteria by Fld, which employs a flavin as prosthetic group and is tolerant to oxidants and iron limitation. Tight membrane binding of FNR allowed solid-state electron transfer from PSI bridged by Fd/Fld. Fine tuning of FNR catalytic mechanism led to formidable increases in turnover rates compared with FNRs acting in heterotrophic pathways, favoring Fd/Fld reduction instead of oxygen reduction.
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Affiliation(s)
- Juan José Pierella Karlusich
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Ocampo y Esmeralda, 2000, Rosario, Argentina
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Ocampo y Esmeralda, 2000, Rosario, Argentina.
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Dailey HA, Dailey TA, Gerdes S, Jahn D, Jahn M, O'Brian MR, Warren MJ. Prokaryotic Heme Biosynthesis: Multiple Pathways to a Common Essential Product. Microbiol Mol Biol Rev 2017; 81:e00048-16. [PMID: 28123057 PMCID: PMC5312243 DOI: 10.1128/mmbr.00048-16] [Citation(s) in RCA: 207] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The advent of heme during evolution allowed organisms possessing this compound to safely and efficiently carry out a variety of chemical reactions that otherwise were difficult or impossible. While it was long assumed that a single heme biosynthetic pathway existed in nature, over the past decade, it has become clear that there are three distinct pathways among prokaryotes, although all three pathways utilize a common initial core of three enzymes to produce the intermediate uroporphyrinogen III. The most ancient pathway and the only one found in the Archaea converts siroheme to protoheme via an oxygen-independent four-enzyme-step process. Bacteria utilize the initial core pathway but then add one additional common step to produce coproporphyrinogen III. Following this step, Gram-positive organisms oxidize coproporphyrinogen III to coproporphyrin III, insert iron to make coproheme, and finally decarboxylate coproheme to protoheme, whereas Gram-negative bacteria first decarboxylate coproporphyrinogen III to protoporphyrinogen IX and then oxidize this to protoporphyrin IX prior to metal insertion to make protoheme. In order to adapt to oxygen-deficient conditions, two steps in the bacterial pathways have multiple forms to accommodate oxidative reactions in an anaerobic environment. The regulation of these pathways reflects the diversity of bacterial metabolism. This diversity, along with the late recognition that three pathways exist, has significantly slowed advances in this field such that no single organism's heme synthesis pathway regulation is currently completely characterized.
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Affiliation(s)
- Harry A Dailey
- Department of Microbiology, Department of Biochemistry and Molecular Biology, and Biomedical and Health Sciences Institute, University of Georgia, Athens, Georgia, USA
| | - Tamara A Dailey
- Department of Microbiology, Department of Biochemistry and Molecular Biology, and Biomedical and Health Sciences Institute, University of Georgia, Athens, Georgia, USA
| | - Svetlana Gerdes
- Fellowship for Interpretation of Genomes, Burr Ridge, Illinois, USA
| | - Dieter Jahn
- Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universitaet Braunschweig, Braunschweig, Germany
| | - Martina Jahn
- Institute of Microbiology, Technische Universitaet Braunschweig, Braunschweig, Germany
| | - Mark R O'Brian
- Department of Biochemistry, University at Buffalo, The State University of New York, Buffalo, New York, USA
| | - Martin J Warren
- Department of Biosciences, University of Kent, Canterbury, Kent, United Kingdom
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25
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Pereira N, Shilova IN, Zehr JP. Molecular markers define progressing stages of phosphorus limitation in the nitrogen-fixing cyanobacterium, Crocosphaera. JOURNAL OF PHYCOLOGY 2016; 52:274-282. [PMID: 27037592 DOI: 10.1111/jpy.12396] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/19/2016] [Indexed: 06/05/2023]
Abstract
Crocosphaera watsonii is a marine cyanobacterium that frequently inhabits low phosphate environments in oligotrophic oceans. While C. watsonii has the ability to fix atmospheric nitrogen, its growth may be limited by availability of phosphorus. Biomarkers that indicate cellular phosphorus status give insight into how P-limitation can affect the distribution of nitrogen-fixing cyanobacterial populations. However, adaptation to phosphorus stress is complex and one marker may not be sufficient to determine when an organism is P-limited. In this study, we characterized the transcription of key genes, activated during phosphorus stress in C. watsonii WH8501, to determine how transcription changed during the phosphorus stress response. Transcription of pstS, which encodes a high-affinity phosphate binding protein, was discovered to be quickly up-regulated in phosphorus-depleted cells as an immediate stress response; however, its transcription declined after a period of phosphorus starvation. In addition, diel regulation of pstS in C. watsonii WH8501 complicates the interpretation of this marker in field applications. Transcription of the gene coding for the arsenite efflux protein, arsB, was upregulated after pstS in phosphorus limited cells, but it remained upregulated at later stages of phosphorus limitation. These results demonstrate that a single molecular marker does not adequately represent the entire phosphorus stress response in C. watsonii WH8501. Using both markers, the variations in transcriptional response over a range of degrees of phosphorus limitation may be a better approach for defining cellular phosphorus status.
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Affiliation(s)
- Nicole Pereira
- Ocean Science Department, University of California, Santa Cruz, California, 95064, USA
| | - Irina N Shilova
- Ocean Science Department, University of California, Santa Cruz, California, 95064, USA
| | - Jonathan P Zehr
- Ocean Science Department, University of California, Santa Cruz, California, 95064, USA
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26
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González A, Sevilla E, Bes MT, Peleato ML, Fillat MF. Pivotal Role of Iron in the Regulation of Cyanobacterial Electron Transport. Adv Microb Physiol 2016; 68:169-217. [PMID: 27134024 DOI: 10.1016/bs.ampbs.2016.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iron-containing metalloproteins are the main cornerstones for efficient electron transport in biological systems. The abundance and diversity of iron-dependent proteins in cyanobacteria makes those organisms highly dependent of this micronutrient. To cope with iron imbalance, cyanobacteria have developed a survey of adaptation strategies that are strongly related to the regulation of photosynthesis, nitrogen metabolism and other central electron transfer pathways. Furthermore, either in its ferrous form or as a component of the haem group, iron plays a crucial role as regulatory signalling molecule that directly or indirectly modulates the composition and efficiency of cyanobacterial redox reactions. We present here the major mechanism used by cyanobacteria to couple iron homeostasis to the regulation of electron transport, making special emphasis in processes specific in those organisms.
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Affiliation(s)
| | - E Sevilla
- University of Zaragoza, Zaragoza, Spain
| | - M T Bes
- University of Zaragoza, Zaragoza, Spain
| | | | - M F Fillat
- University of Zaragoza, Zaragoza, Spain.
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27
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Vuorijoki L, Isojärvi J, Kallio P, Kouvonen P, Aro EM, Corthals GL, Jones PR, Muth-Pawlak D. Development of a Quantitative SRM-Based Proteomics Method to Study Iron Metabolism of Synechocystis sp. PCC 6803. J Proteome Res 2015; 15:266-79. [DOI: 10.1021/acs.jproteome.5b00800] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Linda Vuorijoki
- Molecular
Plant Biology, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland
| | - Janne Isojärvi
- Molecular
Plant Biology, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland
| | - Pauli Kallio
- Molecular
Plant Biology, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland
| | - Petri Kouvonen
- Turku
Proteomics Facility, Centre for Biotechnology, University of Turku and Åbo Akademi University, FI-20014 Turku, Finland
| | - Eva-Mari Aro
- Molecular
Plant Biology, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland
| | - Garry L. Corthals
- Turku
Proteomics Facility, Centre for Biotechnology, University of Turku and Åbo Akademi University, FI-20014 Turku, Finland
- Van’t
Hoff Institute for Molecular Sciences, University of Amsterdam, 1018 WV Amsterdam, The Netherlands
| | - Patrik R. Jones
- Department
of Life Sciences, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, United Kingdom
| | - Dorota Muth-Pawlak
- Molecular
Plant Biology, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland
- Turku
Proteomics Facility, Centre for Biotechnology, University of Turku and Åbo Akademi University, FI-20014 Turku, Finland
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28
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Deciphering Mineral Homeostasis in Barley Seed Transfer Cells at Transcriptional Level. PLoS One 2015; 10:e0141398. [PMID: 26536247 PMCID: PMC4633283 DOI: 10.1371/journal.pone.0141398] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/06/2015] [Indexed: 12/13/2022] Open
Abstract
In addition to the micronutrient inadequacy of staple crops for optimal human nutrition, a global downtrend in crop-quality has emerged from intensive breeding for yield. This trend will be aggravated by elevated levels of the greenhouse gas carbon dioxide. Therefore, crop biofortification is inevitable to ensure a sustainable supply of minerals to the large part of human population who is dietary dependent on staple crops. This requires a thorough understanding of plant-mineral interactions due to the complexity of mineral homeostasis. Employing RNA sequencing, we here communicate transfer cell specific effects of excess iron and zinc during grain filling in our model crop plant barley. Responding to alterations in mineral contents, we found a long range of different genes and transcripts. Among them, it is worth to highlight the auxin and ethylene signaling factors Arfs, Abcbs, Cand1, Hps4, Hac1, Ecr1, and Ctr1, diurnal fluctuation components Sdg2, Imb1, Lip1, and PhyC, retroelements, sulfur homeostasis components Amp1, Hmt3, Eil3, and Vip1, mineral trafficking components Med16, Cnnm4, Aha2, Clpc1, and Pcbps, and vacuole organization factors Ymr155W, RabG3F, Vps4, and Cbl3. Our analysis introduces new interactors and signifies a broad spectrum of regulatory levels from chromatin remodeling to intracellular protein sorting mechanisms active in the plant mineral homeostasis. The results highlight the importance of storage proteins in metal ion toxicity-resistance and chelation. Interestingly, the protein sorting and recycling factors Exoc7, Cdc1, Sec23A, and Rab11A contributed to the response as well as the polar distributors of metal-transporters ensuring the directional flow of minerals. Alternative isoform switching was found important for plant adaptation and occurred among transcripts coding for identical proteins as well as transcripts coding for protein isoforms. We also identified differences in the alternative-isoform preference between the treatments, indicating metal-affinity shifts among isoforms of metal transporters. Most important, we found the zinc treatment to impair both photosynthesis and respiration. A wide range of transcriptional changes including stress-related genes and negative feedback loops emphasize the importance to withhold mineral contents below certain cellular levels which otherwise might lead to agronomical impeding side-effects. By illustrating new mechanisms, genes, and transcripts, this report provides a solid platform towards understanding the complex network of plant mineral homeostasis.
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29
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Kaushik MS, Singh P, Tiwari B, Mishra AK. Ferric Uptake Regulator (FUR) protein: properties and implications in cyanobacteria. ANN MICROBIOL 2015. [DOI: 10.1007/s13213-015-1134-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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30
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Sun J, Golbeck JH. The Presence of the IsiA-PSI Supercomplex Leads to Enhanced Photosystem I Electron Throughput in Iron-Starved Cells of Synechococcus sp. PCC 7002. J Phys Chem B 2015; 119:13549-59. [DOI: 10.1021/acs.jpcb.5b02176] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Junlei Sun
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 United States
| | - John H. Golbeck
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 United States
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31
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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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32
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Shen C, Yue R, Sun T, Zhang L, Yang Y, Wang H. OsARF16, a transcription factor regulating auxin redistribution, is required for iron deficiency response in rice (Oryza sativa L.). PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2015; 231:148-58. [PMID: 25576000 DOI: 10.1016/j.plantsci.2014.12.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 11/24/2014] [Accepted: 12/01/2014] [Indexed: 05/18/2023]
Abstract
Plant response to iron deficiency is the most important feature for survival in Fe-limited soils. Several phytohormones, including auxin, are involved in iron uptake and homeostasis. However, the mechanisms behind how auxin participates in the iron deficiency response in rice are largely unknown. We found that OsARF16 was involved in the iron deficiency response and the induction of iron deficiency response genes. Most Fe-deficient symptoms could be partially restored in the osarf16 mutant, including dwarfism, photosynthesis decline, a reduction in iron content and root system architecture (RSA) regulation. OsARF16 expression was induced in the roots and shoots by Fe deprivation. Restoration of the phenotype could also be mimicked by 1-NOA, an auxin influx inhibitor. Furthermore, the qRT-PCR data indicated that the induction of Fe-deficiency response genes by iron deficiency was more compromised in the osarf16 mutant than in Nipponbare. In conclusion, osarf16, an auxin insensitive mutant, was involved in iron deficiency response in rice. Our results reveal a new biological function for OsARF16 and provide important information on how ARF-medicated auxin signaling affects iron signaling and the iron deficiency response. This work may help us to improve production or increased Fe nutrition of rice to iron deficiency by regulating auxin signaling.
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Affiliation(s)
- Chenjia Shen
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
| | - Runqing Yue
- Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | - Tao Sun
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Lei Zhang
- Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, USA
| | - Yanjun Yang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Huizhong Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
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Jiang HB, Song WY, Cheng HM, Qiu BS. The hypothetical protein Ycf46 is involved in regulation of CO2 utilization in the cyanobacterium Synechocystis sp. PCC 6803. PLANTA 2015; 241:145-155. [PMID: 25230699 DOI: 10.1007/s00425-014-2169-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 09/08/2014] [Indexed: 06/03/2023]
Abstract
The Ycf46 mutant of Synechocystis showed growth inhibition under low dissolved CO 2 conditions, suggesting a role for the Ycf46 protein in the process of photosynthetic CO 2 uptake and utilization. Hypothetical chloroplast open reading frame Ycf46 proteins are highly conserved in all cyanobacterial lineages and most algal chloroplast genomes, but their exact function is still unknown. In the cyanobacterium Synechocystis sp. PCC 6803, the Ycf46 encoding gene slr0374 is part of an operon (with slr0373 and slr0376) and responds to many environmental stresses. Transcript levels of the slr0373, slr0374 and slr0376 genes were increased under a low concentration of dissolved inorganic carbon (Ci). Compared with the wild type, the mutant lacking slr0374 showed growth arrest under Ci-deficient conditions but not under iron-deficient or low-light conditions. In addition, the mutant grew more slowly than the wild type under pH 6.0 conditions in which CO2 was the dominant Ci source, indicating the mutant cells had weak CO2 uptake and/or utilization ability. Supplying a high concentration of CO2 (5 %, v/v) to the mutant restored its phenotype to the wild type level. The photosynthetic activity of the mutant was inhibited to a lesser extent by a carbonic anhydrase inhibitor than that of the wild type, which specifically blocked CO2 uptake. Inactivation of slr0374 decreased expression of the ecaB gene and reduced carbonic anhydrase activity. A subcellular localization assay indicated that the Ycf46 protein was soluble. By co-immunoprecipitation assay using Slr0374 as a bait-protein, potential interacting proteins in the size range of 30 kDa were identified. These results suggest that the Ycf46 protein plays a role in the regulation of photosynthesis in cyanobacteria, especially in CO2 uptake and utilization.
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Affiliation(s)
- Hai-Bo Jiang
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Luoyu Road 152, 430079, Wuhan, Hubei, People's Republic of China
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Kłodawska K, Kovács L, Várkonyi Z, Kis M, Sozer Ö, Laczkó-Dobos H, Kóbori O, Domonkos I, Strzałka K, Gombos Z, Malec P. Elevated Growth Temperature Can Enhance Photosystem I Trimer Formation and Affects Xanthophyll Biosynthesis in Cyanobacterium Synechocystis sp. PCC6803 Cells. ACTA ACUST UNITED AC 2014; 56:558-71. [DOI: 10.1093/pcp/pcu199] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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35
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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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Pierella Karlusich JJ, Lodeyro AF, Carrillo N. The long goodbye: the rise and fall of flavodoxin during plant evolution. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:5161-78. [PMID: 25009172 PMCID: PMC4400536 DOI: 10.1093/jxb/eru273] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 05/27/2014] [Accepted: 05/28/2014] [Indexed: 05/18/2023]
Abstract
Ferredoxins are electron shuttles harbouring iron-sulfur clusters that connect multiple oxido-reductive pathways in organisms displaying different lifestyles. Some prokaryotes and algae express an isofunctional electron carrier, flavodoxin, which contains flavin mononucleotide as cofactor. Both proteins evolved in the anaerobic environment preceding the appearance of oxygenic photosynthesis. The advent of an oxygen-rich atmosphere proved detrimental to ferredoxin owing to iron limitation and oxidative damage to the iron-sulfur cluster, and many microorganisms induced flavodoxin expression to replace ferredoxin under stress conditions. Paradoxically, ferredoxin was maintained throughout the tree of life, whereas flavodoxin is absent from plants and animals. Of note is that flavodoxin expression in transgenic plants results in increased tolerance to multiple stresses and iron deficit, through mechanisms similar to those operating in microorganisms. Then, the question remains open as to why a trait that still confers plants such obvious adaptive benefits was not retained. We compare herein the properties of ferredoxin and flavodoxin, and their contrasting modes of expression in response to different environmental stimuli. Phylogenetic analyses suggest that the flavodoxin gene was already absent in the algal lineages immediately preceding land plants. Geographical distribution of phototrophs shows a bias against flavodoxin-containing organisms in iron-rich coastal/freshwater habitats. Based on these observations, we propose that plants evolved from freshwater macroalgae that already lacked flavodoxin because they thrived in an iron-rich habitat with no need to back up ferredoxin functions and therefore no selective pressure to keep the flavodoxin gene. Conversely, ferredoxin retention in the plant lineage is probably related to its higher efficiency as an electron carrier, compared with flavodoxin. Several lines of evidence supporting these contentions are presented and discussed.
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Affiliation(s)
- Juan J Pierella Karlusich
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
| | - Anabella F Lodeyro
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
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Yingping F, Lemeille S, Talla E, Janicki A, Denis Y, Zhang CC, Latifi A. Unravelling the cross-talk between iron starvation and oxidative stress responses highlights the key role of PerR (alr0957) in peroxide signalling in the cyanobacterium Nostoc PCC 7120. ENVIRONMENTAL MICROBIOLOGY REPORTS 2014; 6:468-475. [PMID: 25646537 DOI: 10.1111/1758-2229.12157] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The cyanobacterial phylum includes oxygenic photosynthetic prokaryotes of a wide variety of morphologies, metabolisms and ecologies. Their adaptation to their various ecological niches is mainly achieved by sophisticated regulatory mechanisms and depends on a fine cross-talk between them. We assessed the global transcriptomic response of the filamentous cyanobacterium Nostoc PCC 7120 to iron starvation and oxidative stress. More than 20% of the differentially expressed genes in response to iron stress were also responsive to oxidative stress. These transcripts include antioxidant proteins-encoding genes that confirms that iron depletion leads to reactive oxygen accumulation. The activity of the Fe-superoxide dismutase was not significantly decreased under iron starvation, indicating that the oxidative stress generated under iron deficiency is not a consequence of (SOD) deficiency. The transcriptional data indicate that the adaptation of Nostoc to iron-depleted conditions displays important differences with what has been shown in unicellular cyanobacteria. While the FurA protein that regulates the response to iron deprivation has been well characterized in Nostoc, the regulators in charge of the oxidative stress response are unknown. Our study indicates that the alr0957 (perR) gene encodes the master regulator of the peroxide stress. PerR is a peroxide-sensor repressor that senses peroxide by metal-catalysed oxidation.
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Byun YJ, Koo MY, Joo HJ, Ha-Lee YM, Lee DH. Comparative analysis of gene expression under cold acclimation, deacclimation and reacclimation in Arabidopsis. PHYSIOLOGIA PLANTARUM 2014; 152:256-74. [PMID: 24494996 DOI: 10.1111/ppl.12163] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 12/20/2013] [Accepted: 12/27/2013] [Indexed: 05/20/2023]
Abstract
Cold acclimated plants show an elevated tolerance against subsequent cold stress. Such adaptation requires alterations in gene expression as well as physiological changes. We were interested in gene expression changes at the transcriptional level during adaptation processes. The patterns of transcriptional changes associated with cold acclimation, deacclimation and reacclimation in Arabidopsis leaves were characterized using the Coldstresschip. Gene expression profiles were further analyzed by 'coexpressed gene sets' using gene set enrichment analysis (GSEA). Genes involved in signal transduction through calcium, and cascades of kinases and transcription factor genes, were distinctively induced in the early response of cold acclimation. On the other hand, genes involved in antioxidation, cell wall biogenesis and sterol synthesis were upregulated in the late response of cold acclimation. After the removal of cold, the expression patterns of most genes rapidly returned to the original states. However, photosynthetic light-harvesting complex genes and lipid metabolism-related genes stayed upregulated in cold deacclimated plants compared to non-treated plants. It is also notable that many well-known cold-inducible genes are slightly induced in reacclimation and their expression remains at relatively low levels in cold reacclimation compared to the expression during the first cold acclimation. The results in this study show the dynamic nature of gene expression occurring during cold acclimation, deacclimation and reacclimation. Our results suggest that there is a memory of cold stress and that the 'memory of cold stress' is possibly due to elevated photosynthetic efficiency, modified lipid metabolism, increased calcium signaling, pre-existing defense protein made during first cold acclimation and/or modified signal transduction from pre-existing defense protein.
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Affiliation(s)
- Youn-Jung Byun
- Graduate Department of Life and Pharmaceutical Science, Ewha Womans University, Seoul, 120-750, South Korea
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Wan M, Jin X, Xia J, Rosenberg JN, Yu G, Nie Z, Oyler GA, Betenbaugh MJ. The effect of iron on growth, lipid accumulation, and gene expression profile of the freshwater microalga Chlorella sorokiniana. Appl Microbiol Biotechnol 2014; 98:9473-81. [PMID: 25248441 DOI: 10.1007/s00253-014-6088-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 09/02/2014] [Accepted: 09/09/2014] [Indexed: 10/24/2022]
Abstract
The effects of iron on the growth, lipid accumulation, and gene expression profiles of the limnetic Chlorella sorokiniana CCTCC M209220 under photoautotrophy were investigated. The addition of iron up to 10(-5) mol l(-l) increased final cell densities by nearly 2-fold at 2.3 × 10(7) cells/ml, growth rate by 2-fold, and the length of the exponential phase by 5 days as compared to unsupplemented controls while 10(-3) mol l(-1) iron was toxic. The lipid content increased from 12 % for unsupplemented cultures to 33 % at 10(-4) mol l(-1) iron while the highest overall lipid yield reached 179 mg l(-1). A genefishing and qPCR comparison between the C. sorokiniana at low and high iron levels indicated increases in the expression of several genes, including carbonic anhydrase involved in microalgal cell growth, as well as acc1 and choline transporter related to lipid synthesis. This study provides insights into changes in gene expression and metabolism that accompany iron supplementation to Chlorella as well as potential metabolic engineering targets for improving growth and lipid synthesis in microalgae.
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Affiliation(s)
- Minxi Wan
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, People's Republic of China
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Krynická V, Tichý M, Krafl J, Yu J, Kaňa R, Boehm M, Nixon PJ, Komenda J. Two essential FtsH proteases control the level of the Fur repressor during iron deficiency in the cyanobacterium Synechocystis sp. PCC 6803. Mol Microbiol 2014; 94:609-24. [PMID: 25238320 DOI: 10.1111/mmi.12782] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2014] [Indexed: 12/18/2022]
Abstract
The cyanobacterium Synechocystis sp. PCC 6803 expresses four different FtsH protease subunits (FtsH1-4) that assemble into specific homo- and heterocomplexes. The FtsH2/FtsH3 complex is involved in photoprotection but the physiological roles of the other complexes, notably the essential FtsH1/FtsH3 complex, remain unclear. Here we show that the FtsH1 and FtsH3 proteases are involved in the acclimation of cells to iron deficiency. A mutant conditionally depleted in FtsH3 was unable to induce normal expression of the IsiA chlorophyll-protein and FutA1 iron transporter upon iron deficiency due to a block in transcription, which is regulated by the Fur transcriptional repressor. Levels of Fur declined in the WT and the FtsH2 null mutant upon iron depletion but not in the FtsH3 downregulated strain. A similar stabilizing effect on Fur was also observed in a mutant conditionally depleted in the FtsH1 subunit. Moreover, a mutant overexpressing FtsH1 showed reduced levels of Fur and enhanced accumulation of both IsiA and FutA1 even under iron sufficiency. Analysis of GFP-tagged derivatives and biochemical fractionation supported a common location for FtsH1 and FtsH3 in the cytoplasmic membrane. Overall we propose that degradation of the Fur repressor mediated by the FtsH1/FtsH3 heterocomplex is critical for acclimation to iron depletion.
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Affiliation(s)
- Vendula Krynická
- Institute of Microbiology, Academy of Sciences, Opatovický mlýn, 37981, Třeboň, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budějovice, Czech Republic
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Domínguez-Martín MA, López-Lozano A, Diez J, Gómez-Baena G, Rangel-Zúñiga OA, García-Fernández JM. Physiological regulation of isocitrate dehydrogenase and the role of 2-oxoglutarate in Prochlorococcus sp. strain PCC 9511. PLoS One 2014; 9:e103380. [PMID: 25061751 PMCID: PMC4111581 DOI: 10.1371/journal.pone.0103380] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 07/02/2014] [Indexed: 01/05/2023] Open
Abstract
The enzyme isocitrate dehydrogenase (ICDH; EC 1.1.1.42) catalyzes the oxidative decarboxylation of isocitrate, to produce 2-oxoglutarate. The incompleteness of the tricarboxylic acids cycle in marine cyanobacteria confers a special importance to isocitrate dehydrogenase in the C/N balance, since 2-oxoglutarate can only be metabolized through the glutamine synthetase/glutamate synthase pathway. The physiological regulation of isocitrate dehydrogenase was studied in cultures of Prochlorococcus sp. strain PCC 9511, by measuring enzyme activity and concentration using the NADPH production assay and Western blotting, respectively. The enzyme activity showed little changes under nitrogen or phosphorus starvation, or upon addition of the inhibitors DCMU, DBMIB and MSX. Azaserine, an inhibitor of glutamate synthase, induced clear increases in the isocitrate dehydrogenase activity and icd gene expression after 24 h, and also in the 2-oxoglutarate concentration. Iron starvation had the most significant effect, inducing a complete loss of isocitrate dehydrogenase activity, possibly mediated by a process of oxidative inactivation, while its concentration was unaffected. Our results suggest that isocitrate dehydrogenase responds to changes in the intracellular concentration of 2-oxoglutarate and to the redox status of the cells in Prochlorococcus.
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Affiliation(s)
| | - Antonio López-Lozano
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
| | - Jesús Diez
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
| | - Guadalupe Gómez-Baena
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
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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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43
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Mustila H, Allahverdiyeva Y, Isojärvi J, Aro EM, Eisenhut M. The bacterial-type [4Fe-4S] ferredoxin 7 has a regulatory function under photooxidative stress conditions in the cyanobacterium Synechocystis sp. PCC 6803. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1293-304. [PMID: 24780314 DOI: 10.1016/j.bbabio.2014.04.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Revised: 04/10/2014] [Accepted: 04/13/2014] [Indexed: 12/15/2022]
Abstract
Ferredoxins function as electron carrier in a wide range of metabolic and regulatory reactions. It is not clear yet, whether the multiplicity of ferredoxin proteins is also reflected in functional multiplicity in photosynthetic organisms. We addressed the biological function of the bacterial-type ferredoxin, Fed7 in the cyanobacterium Synechocystis sp. PCC 6803. The expression of fed7 is induced under low CO₂ conditions and further enhanced by additional high light treatment. These conditions are considered as promoting photooxidative stress, and prompted us to investigate the biological function of Fed7 under these conditions. Loss of Fed7 did not inhibit growth of the mutant strain Δfed7 but significantly modulated photosynthesis parameters when the mutant was grown under low CO₂ and high light conditions. Characteristics of the Δfed7 mutant included elevated chlorophyll and photosystem I levels as well as reduced abundance and activity of photosystem II. Transcriptional profiling of the mutant under low CO₂ conditions demonstrated changes in gene regulation of the carbon concentrating mechanism and photoprotective mechanisms such as the Flv2/4 electron valve, the PSII dimer stabilizing protein Sll0218, and chlorophyll biosynthesis. We conclude that the function of Fed7 is connected to coping with photooxidative stress, possibly by constituting a redox-responsive regulatory element in photoprotection. In photosynthetic eukaryotes domains homologous to Fed7 are exclusively found in chloroplast DnaJ-like proteins that are likely involved in remodeling of regulator protein complexes. It is conceivable that the regulatory function of Fed7 evolved in cyanobacteria and was recruited by Viridiplantae as the controller for the chloroplast DnaJ-like proteins.
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Affiliation(s)
- H Mustila
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
| | - Y Allahverdiyeva
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
| | - J Isojärvi
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
| | - E M Aro
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
| | - M Eisenhut
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
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44
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Fillat MF. The FUR (ferric uptake regulator) superfamily: diversity and versatility of key transcriptional regulators. Arch Biochem Biophys 2014; 546:41-52. [PMID: 24513162 DOI: 10.1016/j.abb.2014.01.029] [Citation(s) in RCA: 219] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/27/2014] [Accepted: 01/31/2014] [Indexed: 11/17/2022]
Abstract
Control of metal homeostasis is essential for life in all kingdoms. In most prokaryotic organisms the FUR (ferric uptake regulator) family of transcriptional regulators is involved in the regulation of iron and zinc metabolism through control by Fur and Zur proteins. A third member of this family, the peroxide-stress response PerR, is present in most Gram-positives, establishing a tight functional interaction with the global regulator Fur. These proteins play a pivotal role for microbial survival under adverse conditions and in the expression of virulence in most pathogens. In this paper we present the current state of the art in the knowledge of the FUR family, including those members only present in more reduced numbers of bacteria, namely Mur, Nur and Irr. The huge amount of work done in the two last decades shows that FUR proteins present considerable diversity in their regulatory mechanisms and interesting structural differences. However, much work needs to be done to obtain a more complete picture of this family, especially in connection with the roles of some members as gas and redox sensors as well as to fully characterize their participation in bacterial adaptative responses.
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Affiliation(s)
- María F Fillat
- Department of Biochemistry and Molecular and Cell Biology, Institute for Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Pedro Cerbuna, 12, 50009 Zaragoza, Spain.
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Kranzler C, Lis H, Finkel OM, Schmetterer G, Shaked Y, Keren N. Coordinated transporter activity shapes high-affinity iron acquisition in cyanobacteria. THE ISME JOURNAL 2014; 8:409-17. [PMID: 24088625 PMCID: PMC3906821 DOI: 10.1038/ismej.2013.161] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/01/2013] [Accepted: 08/17/2013] [Indexed: 11/08/2022]
Abstract
Iron bioavailability limits biological activity in many aquatic and terrestrial environments. Broad scale genomic meta-analyses indicated that within a single organism, multiple iron transporters may contribute to iron acquisition. Here, we present a functional characterization of a cyanobacterial iron transport pathway that utilizes concerted transporter activities. Cyanobacteria are significant contributors to global primary productivity with high iron demands. Certain cyanobacterial species employ a siderophore-mediated uptake strategy; however, many strains possess neither siderophore biosynthesis nor siderophore transport genes. The unicellular, planktonic, freshwater cyanobacterium, Synechocystis sp. PCC 6803, employs an alternative to siderophore-based uptake-reduction of Fe(III) species before transport through the plasma membrane. In this study, we combine short-term radioactive iron uptake and reduction assays with a range of disruption mutants to generate a working model for iron reduction and uptake in Synechocystis sp. PCC 6803. We found that the Fe(II) transporter, FeoB, is the major iron transporter in this organism. In addition, we uncovered a link between a respiratory terminal oxidase (Alternate Respiratory Terminal Oxidase) and iron reduction - suggesting a coupling between these two electron transfer reactions. Furthermore, quantitative RNA transcript analysis identified a function for subunits of the Fe(III) transporter, FutABC, in modulating reductive iron uptake. Collectively, our results provide a molecular basis for a tightly coordinated, high-affinity iron transport system.
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Affiliation(s)
- Chana Kranzler
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
| | - Hagar Lis
- Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Omri M Finkel
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Georg Schmetterer
- Institute of Physical Chemistry, University of Vienna, Vienna, Austria
| | - Yeala Shaked
- Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nir Keren
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
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A microarray for assessing transcription from pelagic marine microbial taxa. ISME JOURNAL 2014; 8:1476-91. [PMID: 24477198 DOI: 10.1038/ismej.2014.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 12/16/2013] [Accepted: 12/31/2013] [Indexed: 02/08/2023]
Abstract
Metagenomic approaches have revealed unprecedented genetic diversity within microbial communities across vast expanses of the world's oceans. Linking this genetic diversity with key metabolic and cellular activities of microbial assemblages is a fundamental challenge. Here we report on a collaborative effort to design MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories), a high-density oligonucleotide microarray that targets functional genes of diverse taxa in pelagic and coastal marine microbial communities. MicroTOOLs integrates nucleotide sequence information from disparate data types: genomes, PCR-amplicons, metagenomes, and metatranscriptomes. It targets 19 400 unique sequences over 145 different genes that are relevant to stress responses and microbial metabolism across the three domains of life and viruses. MicroTOOLs was used in a proof-of-concept experiment that compared the functional responses of microbial communities following Fe and P enrichments of surface water samples from the North Pacific Subtropical Gyre. We detected transcription of 68% of the gene targets across major taxonomic groups, and the pattern of transcription indicated relief from Fe limitation and transition to N limitation in some taxa. Prochlorococcus (eHLI), Synechococcus (sub-cluster 5.3) and Alphaproteobacteria SAR11 clade (HIMB59) showed the strongest responses to the Fe enrichment. In addition, members of uncharacterized lineages also responded. The MicroTOOLs microarray provides a robust tool for comprehensive characterization of major functional groups of microbes in the open ocean, and the design can be easily amended for specific environments and research questions.
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Anfelt J, Hallström B, Nielsen J, Uhlén M, Hudson EP. Using transcriptomics to improve butanol tolerance of Synechocystis sp. strain PCC 6803. Appl Environ Microbiol 2013; 79:7419-27. [PMID: 24056459 PMCID: PMC3837751 DOI: 10.1128/aem.02694-13] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 09/16/2013] [Indexed: 01/28/2023] Open
Abstract
Cyanobacteria are emerging as promising hosts for production of advanced biofuels such as n-butanol and alkanes. However, cyanobacteria suffer from the same product inhibition problems as those that plague other microbial biofuel hosts. High concentrations of butanol severely reduce growth, and even small amounts can negatively affect metabolic processes. An understanding of how cyanobacteria are affected by their biofuel product can enable identification of engineering strategies for improving their tolerance. Here we used transcriptome sequencing (RNA-Seq) to assess the transcriptome response of Synechocystis sp. strain PCC 6803 to two concentrations of exogenous n-butanol. Approximately 80 transcripts were differentially expressed at 40 mg/liter butanol, and 280 transcripts were different at 1 g/liter butanol. Our results suggest a compromised cell membrane, impaired photosynthetic electron transport, and reduced biosynthesis. Accumulation of intracellular reactive oxygen species (ROS) scaled with butanol concentration. Using the physiology and transcriptomics data, we selected several genes for overexpression in an attempt to improve butanol tolerance. We found that overexpression of several proteins, notably, the small heat shock protein HspA, improved tolerance to butanol. Transcriptomics-guided engineering created more solvent-tolerant cyanobacteria strains that could be the foundation for a more productive biofuel host.
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Affiliation(s)
- Josefine Anfelt
- School of Biotechnology, KTH—Royal Institute of Technology, Stockholm, Sweden
| | - Björn Hallström
- Novo Nordisk Foundation Center for Biosustainability, Science for Life Laboratory, Stockholm, Sweden
| | - Jens Nielsen
- Novo Nordisk Foundation Center for Biosustainability, Science for Life Laboratory, Stockholm, Sweden
- Department of Chemical and Biological Engineering, Chalmers Institute of Technology, Gothenburg, Sweden
| | - Mathias Uhlén
- School of Biotechnology, KTH—Royal Institute of Technology, Stockholm, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Science for Life Laboratory, Stockholm, Sweden
| | - Elton P. Hudson
- School of Biotechnology, KTH—Royal Institute of Technology, Stockholm, Sweden
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The response of the TonB-dependent transport network in Anabaena sp. PCC 7120 to cell density and metal availability. Biometals 2013; 26:549-60. [PMID: 23775668 DOI: 10.1007/s10534-013-9644-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 06/04/2013] [Indexed: 01/20/2023]
Abstract
TonB dependent transporters (TBDT) are an essential protein family in bacteria involved in the uptake of a broad variety of molecules such as siderophore-chelated iron, which was the first described substrate. Meanwhile it is known that TBDTs are involved in the uptake of many metals, sugars and polypeptides. The action of TBDTs is regulated and energized by the plasma membrane anchored TonB, which is charged by a proton pump. The number of the genes coding for TBDTs varies in different species, which might reflect environmental adaptations or evolutionary variations of the system. For example, in the cyanobacterium Anabaena sp. PCC 7120 the large number of 22 genes coding for TBDTs has been identified and the expression of these genes has been explored in the absence of iron or copper as well as under nitrogen starvation. We describe the analysis of the expression of the TBDT genes and the according cytoplasmic-membrane localized components; the latter appear to have a lower degree of complexity in Anabaena sp. PCC 7120. This analysis unravels that the response is not sole dependent on the metal supply, but also on cell culture densities. In addition, we present a large group of FhuA-like genes which is expressed highest under standard conditions suggesting a function distinct from iron or copper transport. The genes are clustered according to the expression profile and the consequences for our understanding of the transport systems in Anabaena sp. PCC 7120 are discussed.
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Summerfield TC, Crawford TS, Young RD, Chua JPS, Macdonald RL, Sherman LA, Eaton-Rye JJ. Environmental pH affects photoautotrophic growth of Synechocystis sp. PCC 6803 strains carrying mutations in the lumenal proteins of PSII. PLANT & CELL PHYSIOLOGY 2013; 54:859-74. [PMID: 23444302 DOI: 10.1093/pcp/pct036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Synechocystis sp. strain PCC 6803 grows photoautotrophically across a broad pH range, but wild-type cultures reach a higher density at elevated pH; however, photoheterotrophic growth is similar at high and neutral pH. A number of PSII mutants each lacking at least one lumenal extrinsic protein, and carrying a second PSII lumenal mutation, are able to grow photoautotrophically in BG-11 medium at pH 10.0, but not pH 7.5. We investigated the basis of this pH effect and observed no pH-specific change in variable fluorescence yield from PSII centers of the wild type or the pH-dependent ΔPsbO:ΔPsbU and ΔPsbV:ΔCyanoQ strains; however, 77 K fluorescence emission spectra indicated increased coupling of the phycobilisome (PBS) antenna at pH 10.0 in all mutants. DNA microarray data showed a cell-wide response to transfer from pH 10.0 to pH 7.5, including decreased mRNA levels of a number of oxidative stress-responsive transcripts. We hypothesize that this transcriptional response led to increased tolerance against reactive oxygen species and in particular singlet oxygen. This response enabled photoautotrophic growth of the PSII mutants at pH 10.0. This hypothesis was supported by increased resistance of all strains to rose bengal at pH 10.0 compared with pH 7.5.
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Affiliation(s)
- Tina C Summerfield
- Department of Botany, University of Otago, PO Box 56, Dunedin, 9054, New Zealand.
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Abstract
Ultraviolet (UV) radiation can cause stresses or act as a photoregulatory signal depending on its wavelengths and fluence rates. Although the most harmful effects of UV on living cells are generally attributed to UV-B radiation, UV-A radiation can also affect many aspects of cellular processes. In cyanobacteria, most studies have concentrated on the damaging effect of UV and defense mechanisms to withstand UV stress. However, little is known about the activation mechanism of signaling components or their pathways which are implicated in the process following UV irradiation. Motile cyanobacteria use a very precise negative phototaxis signaling system to move away from high levels of solar radiation, which is an effective escape mechanism to avoid the detrimental effects of UV radiation. Recently, two different UV-A-induced signaling systems for regulating cyanobacterial phototaxis were characterized at the photophysiological and molecular levels. Here, we review the current understanding of the UV-A mediated signaling pathways in the context of the UV-A perception mechanism, early signaling components, and negative phototactic responses. In addition, increasing evidences supporting a role of pterins in response to UV radiation are discussed. We outline the effect of UV-induced cell damage, associated signaling molecules, and programmed cell death under UV-mediated oxidative stress.
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