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Liu LM, Sun CY, Xi YC, Lu XH, Yong CW, Li SQ, Sun QW, Wang XW, Mao YZ, Chen W, Jiang HB. A global transcriptional activator involved in the iron homeostasis in cyanobacteria. SCIENCE ADVANCES 2024; 10:eadl6428. [PMID: 38959319 PMCID: PMC11221513 DOI: 10.1126/sciadv.adl6428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 05/30/2024] [Indexed: 07/05/2024]
Abstract
Cyanobacteria use a series of adaptation strategies and a complicated regulatory network to maintain intracellular iron (Fe) homeostasis. Here, a global activator named IutR has been identified through three-dimensional chromosome organization and transcriptome analysis in a model cyanobacterium Synechocystis sp. PCC 6803. Inactivation of all three homologous IutR-encoding genes resulted in an impaired tolerance of Synechocystis to Fe deficiency and loss of the responses of Fe uptake-related genes to Fe-deplete conditions. Protein-promoter interaction assays confirmed the direct binding of IutR with the promoters of genes related to Fe uptake, and chromatin immunoprecipitation sequencing analysis further revealed that in addition to Fe uptake, IutR could regulate many other physiological processes involved in intracellular Fe homeostasis. These results proved that IutR is an important transcriptional activator, which is essential for cyanobacteria to induce Fe-deficiency response genes. This study provides in-depth insights into the complicated Fe-deficient signaling network and the molecular mechanism of cyanobacteria adaptation to Fe-deficient environments.
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Affiliation(s)
- Ling-Mei Liu
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
| | - Chuan-Yu Sun
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
| | - Yi-Cao Xi
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Xiao-Hui Lu
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
| | - Cheng-Wen Yong
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Shuang-Qing Li
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Qiao-Wei Sun
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Xin-Wei Wang
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - You-Zhi Mao
- Wuhan Frasergen Bioinformatics Co. Ltd., Wuhan, Hubei, China
| | - Weizhong Chen
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Hai-Bo Jiang
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong, China
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2
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Qiu GW, Zheng WC, Yang HM, Wang YY, Qi X, Huang D, Dai GZ, Shi H, Price NM, Qiu BS. Phosphorus deficiency alleviates iron limitation in Synechocystis cyanobacteria through direct PhoB-mediated gene regulation. Nat Commun 2024; 15:4426. [PMID: 38789507 PMCID: PMC11126600 DOI: 10.1038/s41467-024-48847-4] [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: 09/14/2023] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
Iron and phosphorus are essential nutrients that exist at low concentrations in surface waters and may be co-limiting resources for phytoplankton growth. Here, we show that phosphorus deficiency increases the growth of iron-limited cyanobacteria (Synechocystis sp. PCC 6803) through a PhoB-mediated regulatory network. We find that PhoB, in addition to its well-recognized role in controlling phosphate homeostasis, also regulates key metabolic processes crucial for iron-limited cyanobacteria, including ROS detoxification and iron uptake. Transcript abundances of PhoB-targeted genes are enriched in samples from phosphorus-depleted seawater, and a conserved PhoB-binding site is widely present in the promoters of the target genes, suggesting that the PhoB-mediated regulation may be highly conserved. Our findings provide molecular insights into the responses of cyanobacteria to simultaneous iron/phosphorus nutrient limitation.
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Affiliation(s)
- Guo-Wei Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Wen-Can Zheng
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Hao-Ming Yang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Yu-Ying Wang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Xing Qi
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Da Huang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Guo-Zheng Dai
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Huazhong Shi
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79409, USA
| | - Neil M Price
- Department of Biology, McGill University, 1205 Docteur Penfield, Montreal, Québec, H3A 1B1, Canada
| | - Bao-Sheng Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China.
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3
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Dai GZ, Song WY, Xu HF, Tu M, Yu C, Li ZK, Shang JL, Jin CL, Ding CS, Zuo LZ, Liu YR, Yan WW, Zang SS, Liu K, Zhang Z, Bock R, Qiu BS. Hypothetical chloroplast reading frame 51 encodes a photosystem I assembly factor in cyanobacteria. THE PLANT CELL 2024; 36:1844-1867. [PMID: 38146915 PMCID: PMC11062458 DOI: 10.1093/plcell/koad330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 09/29/2023] [Accepted: 12/20/2023] [Indexed: 12/27/2023]
Abstract
Hypothetical chloroplast open reading frames (ycfs) are putative genes in the plastid genomes of photosynthetic eukaryotes. Many ycfs are also conserved in the genomes of cyanobacteria, the presumptive ancestors of present-day chloroplasts. The functions of many ycfs are still unknown. Here, we generated knock-out mutants for ycf51 (sll1702) in the cyanobacterium Synechocystis sp. PCC 6803. The mutants showed reduced photoautotrophic growth due to impaired electron transport between photosystem II (PSII) and PSI. This phenotype results from greatly reduced PSI content in the ycf51 mutant. The ycf51 disruption had little effect on the transcription of genes encoding photosynthetic complex components and the stabilization of the PSI complex. In vitro and in vivo analyses demonstrated that Ycf51 cooperates with PSI assembly factor Ycf3 to mediate PSI assembly. Furthermore, Ycf51 interacts with the PSI subunit PsaC. Together with its specific localization in the thylakoid membrane and the stromal exposure of its hydrophilic region, our data suggest that Ycf51 is involved in PSI complex assembly. Ycf51 is conserved in all sequenced cyanobacteria, including the earliest branching cyanobacteria of the Gloeobacter genus, and is also present in the plastid genomes of glaucophytes. However, Ycf51 has been lost from other photosynthetic eukaryotic lineages. Thus, Ycf51 is a PSI assembly factor that has been functionally replaced during the evolution of oxygenic photosynthetic eukaryotes.
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Affiliation(s)
- Guo-Zheng Dai
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Wei-Yu Song
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Hai-Feng Xu
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Miao Tu
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Chen Yu
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Zheng-Ke Li
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Jin-Long Shang
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Chun-Lei Jin
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Chao-Shun Ding
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Ling-Zi Zuo
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Yan-Ru Liu
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Wei-Wei Yan
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Sha-Sha Zang
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Ke Liu
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Zheng Zhang
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
| | - Ralph Bock
- Department III, Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
| | - Bao-Sheng Qiu
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, PR China
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4
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Müller B. Iron transport mechanisms and their evolution focusing on chloroplasts. JOURNAL OF PLANT PHYSIOLOGY 2023; 288:154059. [PMID: 37586271 DOI: 10.1016/j.jplph.2023.154059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 07/26/2023] [Accepted: 07/28/2023] [Indexed: 08/18/2023]
Abstract
Iron (Fe) is an essential element for photosynthetic organisms, required for several vital biological functions. Photosynthesis, which takes place in the chloroplasts of higher plants, is the major Fe consumer. Although the components of the root Fe uptake system in dicotyledonous and monocotyledonous plants have been extensively studied, the Fe transport mechanisms of chloroplasts in these two groups of plants have received little attention. This review focuses on the comparative analysis of Fe transport processes in the evolutionary ancestors of chloroplasts (cyanobacteria) with the processes in embryophytes and green algae (Viridiplantae). The aim is to summarize how chloroplasts are integrated into cellular Fe homeostasis and how Fe transporters and Fe transport mechanisms have been modified by evolution.
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Affiliation(s)
- Brigitta Müller
- Department of Plant Physiology and Molecular Biology, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, H-1117, Hungary.
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Diversity and Evolution of Iron Uptake Pathways in Marine Cyanobacteria from the Perspective of the Coastal Strain Synechococcus sp. Strain PCC 7002. Appl Environ Microbiol 2023; 89:e0173222. [PMID: 36533965 PMCID: PMC9888192 DOI: 10.1128/aem.01732-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Marine cyanobacteria contribute to approximately half of the ocean primary production, and their biomass is limited by low iron (Fe) bioavailability in many regions of the open seas. The mechanisms by which marine cyanobacteria overcome Fe limitation remain unclear. In this study, multiple Fe uptake pathways have been identified in a coastal strain of Synechococcus sp. strain PCC 7002. A total of 49 mutants were obtained by gene knockout methods, and 10 mutants were found to have significantly decreased growth rates compared to the wild type (WT). The genes related to active Fe transport pathways such as TonB-dependent transporters and the synthesis and secretion of siderophores are found to be essential for the adaptation of Fe limitation in Synechococcus sp. PCC 7002. By comparing the Fe uptake pathways of this coastal strain with other open-ocean cyanobacterial strains, it can be concluded that the Fe uptake strategies from different cyanobacteria have a strong relationship with the Fe bioavailability in their habitats. The evolution and adaptation of cyanobacterial iron acquisition strategies with the change of iron environments from ancient oceans to modern oceans are discussed. This study provides new insights into the diversified strategies of marine cyanobacteria in different habitats from temporal and spatial scales. IMPORTANCE Iron (Fe) is an important limiting factor of marine primary productivity. Cyanobacteria, the oldest photosynthetic oxygen-evolving organisms on the earth, play crucial roles in marine primary productivity, especially in the oligotrophic ocean. How they overcome Fe limitation during the long-term evolution process has not been fully revealed. Fe uptake mechanisms of cyanobacteria have been partially studied in freshwater cyanobacteria but are largely unknown in marine cyanobacterial species. In this paper, the characteristics of Fe uptake mechanisms in a coastal model cyanobacterium, Synechococcus sp. PCC 7002, were studied. Furthermore, the relationship between Fe uptake strategies and Fe environments of cyanobacterial habitats has been revealed from temporal and spatial scales, which provides a good case for marine microorganisms adapting to changes in the marine environment.
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6
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Iron transport in cyanobacteria - from molecules to communities. Trends Microbiol 2021; 30:229-240. [PMID: 34175176 DOI: 10.1016/j.tim.2021.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 06/01/2021] [Accepted: 06/01/2021] [Indexed: 11/22/2022]
Abstract
Iron is an essential micronutrient for the ecologically important photoautotrophic cyanobacteria which are found across diverse aquatic environments. Low concentrations and poor bioavailability of certain iron species exert a strong control on cyanobacterial growth, affecting ecosystem structure and biogeochemical cycling. Here, we review the iron-acquisition pathways cyanobacteria utilize for overcoming these challenges. As the molecular details of cyanobacterial iron transport are being uncovered, an overall scheme of how cyanobacteria handle and exploit this scarce and redox-active micronutrient is emerging. Importantly, the range of biological solutions used by cyanobacteria to increase iron fluxes goes beyond transport and includes behavioral traits of colonial cyanobacteria and intricate cyanobacteria-bacteria interactions.
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7
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Liu LM, Li DL, Deng B, Wang XW, Jiang HB. Special roles for efflux systems in iron homeostasis of non-siderophore-producing cyanobacteria. Environ Microbiol 2021; 24:551-565. [PMID: 33817959 DOI: 10.1111/1462-2920.15506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 04/03/2021] [Indexed: 11/28/2022]
Abstract
In oligotrophic oceans, low bioavailability of Fe is a key factor limiting primary productivity. However, excessive Fe in cells leads to the Fenton reaction, which is toxic to cells. Cyanobacteria must strictly maintain intracellular Fe homeostasis. Here, we knocked out a series of genes encoding efflux systems in Synechocystis sp. PCC 6803, and found eight genes that are required for high Fe detoxification. Unexpectedly, the HlyBD-TolC efflux system plays an important role in the adaptation of Synechocystis under Fe-deficient conditions. Mutants of HlyD and TolC grew worse than the wild-type strain under low-Fe conditions and showed significantly lower intracellular Fe contents than the wild-type strain. We excluded the possibility that the low Fe sensitivity of the HlyBD-TolC mutants was caused by a loss of the S-layer, the main extracellular protein secreted via this efflux system. Inactivation of the HlyD protein influenced type IV pili formation and direct inactivation of type IV pili related genes affected the adaptation to low-Fe conditions. HlyBD-TolC system is likely involved in the formation of type IV pili and indirectly influenced Fe acquisition. Our findings suggest that efflux system in non-siderophore-producing cyanobacteria can facilitate Fe uptake and help cells adapt to Fe-deficient conditions via novel pathways.
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Affiliation(s)
- Ling-Mei Liu
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.,Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong, 519080, China
| | - Ding-Lan Li
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Bin Deng
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Xin-Wei Wang
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong, 519080, China.,School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, China
| | - Hai-Bo Jiang
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.,Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong, 519080, China.,School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, China
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8
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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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9
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Qiu GW, Jiang HB, Lis H, Li ZK, Deng B, Shang JL, Sun CY, Keren N, Qiu BS. A unique porin meditates iron-selective transport through cyanobacterial outer membranes. Environ Microbiol 2020; 23:376-390. [PMID: 33196124 DOI: 10.1111/1462-2920.15324] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Revised: 11/02/2020] [Accepted: 11/12/2020] [Indexed: 10/23/2022]
Abstract
Cyanobacteria are globally important primary producers and nitrogen fixers with high iron demands. Low ambient dissolved iron concentrations in many aquatic environments mean that these organisms must maintain sufficient and selective transport of iron into the cell. However, the nature of iron transport pathways through the cyanobacterial outer membrane remains obscure. Here we present multiple lines of experimental evidence that collectively support the existence of a novel class of substrate-selective iron porin, Slr1908, in the outer membrane of the cyanobacterium Synechocystis sp. PCC 6803. Elemental composition analysis and short-term iron uptake assays with mutants in Slr1908 reveal that this protein is primarily involved in inorganic iron uptake and contributes less to the accumulation of other metals. Homologues of Slr1908 are widely distributed in both freshwater and marine cyanobacteria, most notably in unicellular marine diazotrophs. Complementary experiments with a homologue of Slr1908 in Synechococcus sp. PCC 7002 restored the phenotype of Synechocystis knockdown mutants, showing that this siderophore producing species also possesses a porin with a similar function in Fe transport. The involvement of a substrate-selective porins in iron uptake may allow cyanobacteria to tightly control iron flux into the cell, particularly in environments where iron concentrations fluctuate.
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Affiliation(s)
- Guo-Wei Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
| | - Hai-Bo Jiang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
| | - Hagar Lis
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, Israel
| | - Zheng-Ke Li
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
| | - Bin Deng
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
| | - Jin-Long Shang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
| | - Chuan-Yu Sun
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
| | - Nir Keren
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, Israel
| | - Bao-Sheng Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
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10
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Liu W, Wang J, Liu T. Low pH rather than high CO 2 concentration itself inhibits growth of Arthrospira. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 666:572-580. [PMID: 30807947 DOI: 10.1016/j.scitotenv.2019.02.312] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 02/18/2019] [Accepted: 02/20/2019] [Indexed: 05/21/2023]
Abstract
Microalga is a promising candidate for bio-mitigation of CO2. It has been longtime recognized that high CO2 concentration would impose stresses on microalga to suppress the growth. However, this concept was challenged in this research by investigating the growth, photosynthesis and anti-oxidant characteristics of Arthrospira platensis under independent effects of CO2 concentrations and pH. Results showed the growth of A. platensis was only inhibited when broth was in acidic pH. Microalgal cells could deal with high CO2 concentration readily if medium pH was maintained in favorite level. Photosynthesis was inhibited swiftly and significantly under acidified condition. The singlet oxygen was produced in low level for alkalic pH treatment, however it burst quickly after low pH stress was imposed. Accordingly, it was proposed that the phenomena of high CO2 intolerance was caused by CO2 induced pH decline rather than high CO2 concentration itself. This finding has significance on large scale application of microalga based CO2 mitigation and flue gas treatment since it proved concentrated CO2 could be directly assimilated without dilution.
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Affiliation(s)
- Wen Liu
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Junfeng Wang
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, 266101, PR China.
| | - Tianzhong Liu
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, 266101, PR China.
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11
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Outer Membrane Iron Uptake Pathways in the Model Cyanobacterium Synechocystis sp. Strain PCC 6803. Appl Environ Microbiol 2018; 84:AEM.01512-18. [PMID: 30076192 DOI: 10.1128/aem.01512-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 07/21/2018] [Indexed: 02/01/2023] Open
Abstract
Cyanobacteria are foundational drivers of global nutrient cycling, with high intracellular iron (Fe) requirements. Fe is found at extremely low concentrations in aquatic systems, however, and the ways in which cyanobacteria take up Fe are largely unknown, especially the initial step in Fe transport across the outer membrane. Here, we identified one TonB protein and four TonB-dependent transporters (TBDTs) of the energy-requiring Fe acquisition system and six porins of the passive diffusion Fe uptake system in the model cyanobacterium Synechocystis sp. strain PCC 6803. The results experimentally demonstrated that TBDTs not only participated in organic ferri-siderophore uptake but also in inorganic free Fe (Fe') acquisition. 55Fe uptake rate measurements showed that a TBDT quadruple mutant acquired Fe at a lower rate than the wild type and lost nearly all ability to take up ferri-siderophores, indicating that TBDTs are critical for siderophore uptake. However, the mutant retained the ability to take up Fe' at 42% of the wild-type Fe' uptake rate, suggesting additional pathways of Fe' acquisition besides TBDTs, likely by porins. Mutations in four of the six porin-encoding genes produced a low-Fe-sensitive phenotype, while a mutation in all six genes was lethal to cell survival. These diverse outer membrane Fe uptake pathways reflect cyanobacterial evolution and adaptation under a range of Fe regimes across aquatic systems.IMPORTANCE Cyanobacteria are globally important primary producers and contribute about 25% of global CO2 fixation. Low Fe bioavailability in surface waters is thought to limit the primary productivity in as much as 40% of the global ocean. The Fe acquisition strategies that cyanobacteria have evolved to overcome Fe deficiency remain poorly characterized. We experimentally characterized the key players and the cooperative work mode of two Fe uptake pathways, including an active uptake pathway and a passive diffusion pathway in the model cyanobacterium Synechocystis sp. PCC 6803. Our finding proved that cyanobacteria use ferri-siderophore transporters to take up Fe', and they shed light on the adaptive mechanisms of cyanobacteria to cope with widespread Fe deficiency across aquatic environments.
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12
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A Specific Single Nucleotide Polymorphism in the ATP Synthase Gene Significantly Improves Environmental Stress Tolerance of Synechococcus elongatus PCC 7942. Appl Environ Microbiol 2018; 84:AEM.01222-18. [PMID: 30006407 DOI: 10.1128/aem.01222-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/11/2018] [Indexed: 01/08/2023] Open
Abstract
In response to a broad range of habitats and environmental stresses, cyanobacteria have evolved various effective acclimation strategies, which will be helpful for improving the stress tolerances of photosynthetic organisms, including higher plants. Synechococcus elongatus UTEX 2973 and PCC 7942 possess genomes that are 99.8% identical but exhibit significant differences in cell growth and stress tolerance. In this study, we found that a single amino acid substitution at FoF1 ATP synthase subunit α (AtpA), C252Y, is the primary contributor to the improved stress tolerance of S. elongatus UTEX 2973. Site-saturation mutagenesis experiments showed that point mutations of cysteine 252 to any of the four conjugated amino acids could significantly improve the stress tolerance of S. elongatus PCC 7942. We further confirmed that the C252Y mutation increases AtpA protein levels, intracellular ATP synthase activity, intracellular ATP abundance, transcription of psbA genes (especially psbA2), photosystem II activity, and glycogen accumulation in S. elongatus PCC 7942. This work highlights the importance of AtpA in improving the stress tolerance of cyanobacteria and provides insight into how cyanobacteria evolve via point mutations in the face of environmental selection pressures.IMPORTANCE Two closely related Synechococcus strains showed significantly different tolerances to high light and high temperature but limited genomic differences, providing us opportunities to identify key genes responsible for stress acclimation by a gene complementation approach. In this study, we confirmed that a single point mutation in the α subunit of FoF1 ATP synthase (AtpA) contributes mainly to the improved stress tolerance of Synechococcus elongatus UTEX 2973. The point mutation of AtpA, the important ATP-generating complex of photosynthesis, increases AtpA protein levels, intracellular ATP synthase activity, and ATP concentrations under heat stress, as well as photosystem II activity. This work proves the importance of ATP synthase in cyanobacterial stress acclimation and provides a good target for future improvement of cyanobacterial stress tolerance by metabolic engineering.
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13
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Zhao J, Gao F, Fan DY, Chow WS, Ma W. NDH-1 Is Important for Photosystem I Function of Synechocystis sp. Strain PCC 6803 under Environmental Stress Conditions. FRONTIERS IN PLANT SCIENCE 2018; 8:2183. [PMID: 29387069 PMCID: PMC5776120 DOI: 10.3389/fpls.2017.02183] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 12/12/2017] [Indexed: 05/24/2023]
Abstract
Cyanobacterial NDH-1 interacts with photosystem I (PSI) to form an NDH-1-PSI supercomplex. Here, we observed that absence of NDH-1 had little, if any, effect on the functional fractions of PSI under growth conditions, but significantly reduced the functional fractions of PSI when cells of Synechocystis sp. strain PCC 6803 were moved to conditions of multiple stresses. The significant reduction in NDH-1-dependent functional fraction of PSI was initiated after PSII activity was impaired. This finding is consistent with our observation that the functional fraction of PSI under growth conditions was rapidly and significantly decreased with increasing concentrations of DCMU, which rapidly and significantly suppressed PSII activity by blocking the transfer of electrons from QA to QB in the PSII reaction center. Furthermore, absence of NDH-1 resulted in the PSI limitation at the functionality of PSI itself but not its donor-side and acceptor-side under conditions of multiple stresses. This was supported by the result of a significant destabilization of the PSI complex in the absence of NDH-1 but the presence of multiple stresses. Based on the above results, we propose that NDH-1 is important for PSI function of Synechocystis sp. strain PCC 6803 mainly via maintaining stabilization of PSI under conditions of environmental stresses.
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Affiliation(s)
- Jiaohong Zhao
- Department of Biology, College of Life and Environment Sciences, Shanghai Normal University, Shanghai, China
| | - Fudan Gao
- Department of Biology, College of Life and Environment Sciences, Shanghai Normal University, Shanghai, China
| | - Da-Yong Fan
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Wah Soon Chow
- Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Weimin Ma
- Department of Biology, College of Life and Environment Sciences, Shanghai Normal University, Shanghai, China
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14
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Babykin MM, Obando TSA, Zinchenko VV. TonB-Dependent Utilization of Dihydroxamate Xenosiderophores in Synechocystis sp. PCC 6803. Curr Microbiol 2017; 75:117-123. [PMID: 28900692 DOI: 10.1007/s00284-017-1355-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 09/06/2017] [Indexed: 01/04/2023]
Abstract
In Gram-negative bacteria, transport of ferric siderophores through outer membrane is a complex process that requires specific outer membrane transporters and energy-transducing TonB-ExbB-ExbD system in the cytoplasmic membrane. The genome of the non-siderophore-producing cyanobacterium Synechocystis sp. PCC 6803 encodes all putative components of the siderophore-mediated iron uptake system. So far, there has been no experimental evidence for the existence of such a pathway in this organism. On the contrary, its reductive iron uptake pathway has been studied in detail. We demonstrate that Synechocystis sp. PCC 6803 is capable of using dihydroxamate xenosiderophores, either ferric schizokinen (FeSK) or a siderophore of the filamentous cyanobacterium Anabaena variabilis ATCC 29413 (SAV), as the sole source of iron. Inactivation of the tonB gene or the exbB1-exbD1 gene cluster resulted in an inability to utilize these siderophores. At the same time, the inactivation of the feoB gene encoding FeoB plasma membrane ferrous iron transporter, or one of the futB or futC genes encoding permease and ATPase subunit of FutABC ferric iron transporter, did not impair the ability of cells to utilize FeSK or SAV as the sole source of iron for growth. Our data suggest that cyanobacterium Synechocystis sp. PCC 6803 is capable of acquiring iron-siderophore complexes in a TonB-dependent manner without iron reduction in the periplasm.
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Affiliation(s)
- Michael M Babykin
- International Biotechnological Centre, Moscow State University, Moscow, Russian Federation, 119991
| | - Tobias S A Obando
- Department of Genetics, Moscow State University, Moscow, Russian Federation, 119991
| | - Vladislav V Zinchenko
- Department of Genetics, Moscow State University, Moscow, Russian Federation, 119991.
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15
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Zhang H, Liu Y, Yao C, Cao X, Tian J, Xue S. FabG can function as PhaB for poly-3-hydroxybutyrate biosynthesis in photosynthetic cyanobacteria Synechocystis sp. PCC 6803. Bioengineered 2017; 8:707-715. [PMID: 28494182 DOI: 10.1080/21655979.2017.1317574] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The production of poly-3-hydroxybutyrate (PHB) by photosynthetic cyanobacteria is a potentially sustainable production method for the biodegradable plastics industry. β-Ketoacyl-ACP reductase (FabG), from the photosynthetic cyanobacterium Synechocystis sp. PCC 6803 (SpFabG), is the first NADPH-dependent reductase in the fatty acid biosynthesis pathway. Its structure is similar to that of acetoacetyl-CoA reductase (SpPhaB), which is critical for PHB synthesis and can replace SpPhaB for acetoacetyl-CoA reduction in vitro. However, the specific function of SpFabG in fatty acid synthesis and whether SpFabG could participate in PHB synthesis in vivo were not yet clear. In this study, the role of SpFabG in fatty acid synthesis was first verified in vivo by knocking down and overexpressing of fabG. It was shown that SpFabG was essential yet not rate-limiting for fatty acid biosynthesis. The biochemical characterization of SpFabG using acetoacetyl-CoA as the substrate showed that the optimum temperature, optimum pH, Km and kcat were 30°C, 7, 2.30 mM, and 19.85 s-1, respectively, which exemplified the ability of SpFabG to reduce acetoacetyl-CoA with a relatively low affinity and weak catalytic efficiency. Functional analysis of SpFabG in vivo indicated that SpFabG was able to partially complement SpPhaB under nitrogen-deprived conditions, and overexpression of fabG led to the diversion of partial carbon flux from fatty acid toward PHB synthesis.
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Affiliation(s)
- Haowei Zhang
- a School of Engineering, Dalian Polytechnic University , Liaoning , Dalian , China
| | - Yinghui Liu
- b Marine Bioengineering Group, Dalian Institute of Chemical Physics , Chinese Academy of Sciences , Dalian , China
| | - Changhong Yao
- c Department of Pharmaceutical & Biological Engineering , School of Chemical Engineering, Sichuan University , Chengdu , Sichuan , China
| | - Xupeng Cao
- b Marine Bioengineering Group, Dalian Institute of Chemical Physics , Chinese Academy of Sciences , Dalian , China
| | - Jing Tian
- a School of Engineering, Dalian Polytechnic University , Liaoning , Dalian , China
| | - Song Xue
- b Marine Bioengineering Group, Dalian Institute of Chemical Physics , Chinese Academy of Sciences , Dalian , China
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16
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Kranzler C, Kessler N, Keren N, Shaked Y. Enhanced ferrihydrite dissolution by a unicellular, planktonic cyanobacterium: a biological contribution to particulate iron bioavailability. Environ Microbiol 2016; 18:5101-5111. [DOI: 10.1111/1462-2920.13496] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 07/31/2016] [Accepted: 08/11/2016] [Indexed: 11/27/2022]
Affiliation(s)
- Chana Kranzler
- Department of Plant and Environmental Sciences; The Alexander Silberman Institute of Life Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem; Jerusalem Israel
- Interuniversity Institute for Marine Sciences in Eilat; POB 469 Eilat 88103 Israel
| | - Nivi Kessler
- Interuniversity Institute for Marine Sciences in Eilat; POB 469 Eilat 88103 Israel
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem; Jerusalem Israel
| | - Nir Keren
- Department of Plant and Environmental Sciences; The Alexander Silberman Institute of Life Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem; Jerusalem Israel
| | - Yeala Shaked
- Interuniversity Institute for Marine Sciences in Eilat; POB 469 Eilat 88103 Israel
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem; Jerusalem Israel
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17
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Xu N, Qiu GW, Lou WJ, Li ZK, Jiang HB, Price NM, Qiu BS. Identification of an iron permease, cFTR1, in cyanobacteria involved in the iron reduction/re-oxidation uptake pathway. Environ Microbiol 2016; 18:5005-5017. [DOI: 10.1111/1462-2920.13464] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 07/19/2016] [Accepted: 07/23/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Ning Xu
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology; Central China Normal University; Wuhan Hubei 430079 People's Republic of China
| | - Guo-Wei Qiu
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology; Central China Normal University; Wuhan Hubei 430079 People's Republic of China
| | - Wen-Jing Lou
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology; Central China Normal University; Wuhan Hubei 430079 People's Republic of China
| | - Zheng-Ke Li
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology; Central China Normal University; Wuhan Hubei 430079 People's Republic of China
| | - Hai-Bo Jiang
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology; Central China Normal University; Wuhan Hubei 430079 People's Republic of China
| | - Neil M. Price
- Department of Biology; McGill University; 1205 Docteur Penfield Montreal Québec H3A 1B1 Canada
| | - Bao-Sheng Qiu
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology; Central China Normal University; Wuhan Hubei 430079 People's Republic of China
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18
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Sure S, Ackland ML, Gaur A, Gupta P, Adholeya A, Kochar M. Probing Synechocystis-Arsenic Interactions through Extracellular Nanowires. Front Microbiol 2016; 7:1134. [PMID: 27486454 PMCID: PMC4949250 DOI: 10.3389/fmicb.2016.01134] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 07/07/2016] [Indexed: 11/13/2022] Open
Abstract
Microbial nanowires (MNWs) can play an important role in the transformation and mobility of toxic metals/metalloids in environment. The potential role of MNWs in cell-arsenic (As) interactions has not been reported in microorganisms and thus we explored this interaction using Synechocystis PCC 6803 as a model system. The effect of half maximal inhibitory concentration (IC50) [~300 mM As (V) and ~4 mM As (III)] and non-inhibitory [4X lower than IC50, i.e., 75 mM As (V) and 1 mM As (III)] of As was studied on Synechocystis cells in relation to its effect on Chlorophyll (Chl) a, type IV pili (TFP)-As interaction and intracellular/extracellular presence of As. In silico analysis showed that subunit PilA1 of electrically conductive TFP, i.e., microbial nanowires of Synechocystis have putative binding sites for As. In agreement with in silico analysis, transmission electron microscopy analysis showed that As was deposited on Synechocystis nanowires at all tested concentrations. The potential of Synechocystis nanowires to immobilize As can be further enhanced and evaluated on a large scale and thus can be applied for bioremediation studies.
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Affiliation(s)
- Sandeep Sure
- TERI-Deakin Nano biotechnology Centre, The Energy and Resources Institute Gurgaon, India
| | - M L Ackland
- Centre for Cellular & Molecular Biology, Deakin University, Melbourne VIC, Australia
| | - Aditya Gaur
- TERI-Deakin Nano biotechnology Centre, The Energy and Resources Institute Gurgaon, India
| | - Priyanka Gupta
- TERI-Deakin Nano biotechnology Centre, The Energy and Resources Institute Gurgaon, India
| | - Alok Adholeya
- TERI-Deakin Nano biotechnology Centre, The Energy and Resources Institute Gurgaon, India
| | - Mandira Kochar
- TERI-Deakin Nano biotechnology Centre, The Energy and Resources Institute Gurgaon, India
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19
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Li ZK, Dai GZ, Juneau P, Qiu BS. Capsular polysaccharides facilitate enhanced iron acquisition by the colonial cyanobacterium Microcystis sp. isolated from a freshwater lake. JOURNAL OF PHYCOLOGY 2016; 52:105-115. [PMID: 26987092 DOI: 10.1111/jpy.12372] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 10/29/2015] [Indexed: 06/05/2023]
Abstract
Microcystis sp., especially in its colonial form, is a common dominant species during cyanobacterial blooms in many iron-deficient water bodies. It is still not entirely clear, however, how the colonial forms of Microcystis acclimate to iron-deficient habitats, and the responses of unicellular and colonial forms to iron-replete and iron-deficient conditions were examined here. Growth rates and levels of photosynthetic pigments declined to a greater extent in cultures of unicellular Microcystis than in cultures of the colonial form in response to decreasing iron concentrations, resulting in the impaired photosynthetic performance of unicellular Microcystis as compared to colonial forms as measured by variable fluorescence and photosynthetic oxygen evolution. These results indicate that the light-harvesting ability and photosynthetic capacity of colonial Microcystis was less affected by iron deficiency than the unicellular form. The carotenoid contents and nonphotochemical quenching of colonial Microcystis were less reduced than those of the unicellular form under decreasing iron concentrations, indicating that the colonial morphology enhanced photoprotection and acclimation to iron-deficient conditions. Furthermore, large amounts of iron were detected in the capsular polysaccharides (CPS) of the colonies, and more iron was found to be attached to the colonial Microcystis CPS under decreasing iron conditions as compared to unicellular cultures. These results demonstrated that colonial Microcystis can acclimate to iron deficiencies better than the unicellular form, and that CPS plays an important role in their acclimation advantage in iron-deficient waters.
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Affiliation(s)
- Zheng-Ke Li
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Guo-Zheng Dai
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Philippe Juneau
- Department of Biological Sciences-TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Université du Québec à Montréal, CP8888 Succursale Centre-ville, Montréal, Québec, Canada, H3C 3P8
| | - Bao-Sheng Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
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20
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Hudek L, Pearson L, Michalczyk AA, Bräu L, Neilan BA, Ackland ML. Characterization of two cation diffusion facilitators NpunF0707 and NpunF1794 in Nostoc punctiforme. J Appl Microbiol 2015; 119:1357-70. [PMID: 26299407 DOI: 10.1111/jam.12942] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 07/15/2015] [Accepted: 08/11/2015] [Indexed: 11/28/2022]
Abstract
AIMS To characterize genes involved in maintaining homeostatic levels of zinc in the cyanobacterium Nostoc punctiforme. METHODS AND RESULTS Metal efflux transporters play a central role in maintaining homeostatic levels of trace elements such as zinc. Sequence analyses of the N. punctiforme genome identified two potential cation diffusion facilitator (CDF) metal efflux transporters, Npun_F0707 (Cdf31) and Npun_F1794 (Cdf33). Deletion of either Cdf31or Cdf33 resulted in increased zinc retention over 3 h. Interestingly, Cdf31(-) and Cdf33(-) mutants showed no change in sensitivity to zinc exposure in comparison with the wild type, suggesting some compensatory capacity for the loss of each other. Using qRT-PCR, a possible interaction was observed between the two cdf's, where the Cdf31(-) mutant had a more profound effect on cdf33 expression than Cdf33(-) did on cdf31. Over-expression of Cdf31 and Cdf33 in ZntA(-) - and ZitB(-) -deficient Escherichia coli revealed function similarities between the ZntA and ZitB of E. coli and the cyanobacterial transporters. CONCLUSIONS The data presented shed light on the function of two important transporters that regulate zinc homeostasis in N. punctiforme. SIGNIFICANCE AND IMPACT OF THE STUDY This study shows for the first time the functional characterization of two cyanobacterial zinc efflux proteins belonging to the CDF family.
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Affiliation(s)
- L Hudek
- Centre for Regional and Rural Futures, Deakin University, Burwood, Melbourne, Vic., Australia.,Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Vic., Australia
| | - L Pearson
- Australian Centre for Astrobiology and School of Biotechnology and Biological Sciences, University of New South Wales, Sydney, NSW, Australia
| | - A A Michalczyk
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Vic., Australia
| | - L Bräu
- Centre for Regional and Rural Futures, Deakin University, Burwood, Melbourne, Vic., Australia.,Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Vic., Australia
| | - B A Neilan
- Australian Centre for Astrobiology and School of Biotechnology and Biological Sciences, University of New South Wales, Sydney, NSW, Australia
| | - M L Ackland
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Vic., Australia
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21
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Hudek L, Bräu L, Michalczyk AA, Neilan BA, Meeks JC, Ackland ML. The ZntA-like NpunR4017 plays a key role in maintaining homeostatic levels of zinc in Nostoc punctiforme. Appl Microbiol Biotechnol 2015; 99:10559-74. [PMID: 26290176 DOI: 10.1007/s00253-015-6922-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/02/2015] [Accepted: 08/05/2015] [Indexed: 11/28/2022]
Abstract
Analysis of cellular response to zinc exposure provides insights into how organisms maintain homeostatic levels of zinc that are essential, while avoiding potentially toxic cytosolic levels. Using the cyanobacterium Nostoc punctiforme as a model, qRT-PCR analyses established a profile of the changes in relative mRNA levels of the ZntA-like zinc efflux transporter NpunR4017 in response to extracellular zinc. In cells treated with 18 μM of zinc for 1 h, NpunR4017 mRNA levels increased by up to 1300 % above basal levels. The accumulation and retention of radiolabelled (65)Zn by NpunR4107-deficient and overexpressing strains were compared to wild-type levels. Disruption of NpunR4017 resulted in a significant increase in zinc accumulation up to 24 % greater than the wild type, while cells overexpressing NpunR4107 accumulated 22 % less than the wild type. Accumulation of (65)Zn in ZntA(-) Escherichia coli overexpressing NpunR4017 was reduced by up to 21 %, indicating the capacity for NpunR4017 to compensate for the loss of ZntA. These findings establish the newly identified NpunR4017 as a zinc efflux transporter and a key transporter for maintaining zinc homeostasis in N. punctiforme.
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Affiliation(s)
- L Hudek
- Centre for Regional and Rural Futures, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia. .,Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.
| | - L Bräu
- Centre for Regional and Rural Futures, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.,School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia
| | - A A Michalczyk
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.,School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia
| | - B A Neilan
- Australian Centre for Astrobiology and School of Biotechnology and Biological Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - J C Meeks
- Department of Microbiology, University of California, Davis, CA, 95616, USA
| | - M L Ackland
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.,School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia
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22
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Cation Diffusion Facilitator family: Structure and function. FEBS Lett 2015; 589:1283-95. [PMID: 25896018 DOI: 10.1016/j.febslet.2015.04.007] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/01/2015] [Accepted: 04/08/2015] [Indexed: 01/13/2023]
Abstract
The Cation Diffusion Facilitators (CDFs) form a family of membrane-bound proteins capable of transporting zinc and other heavy metal ions. Involved in metal tolerance/resistance by efflux of ions, CDF proteins share a two-modular architecture consisting of a transmembrane domain (TMD) and C-terminal domain (CTD) that protrudes into the cytoplasm. Discovery of a Zn²⁺ and Cd²⁺ CDF transporter from a marine bacterium Maricaulis maris that does not possess the CTD questions current perceptions regarding this family of proteins. This article describes a new, CTD-lacking subfamily of CDFs and our current knowledge about this family of proteins in the view of these findings.
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23
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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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24
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Raimunda D, Elso-Berberián G. Functional characterization of the CDF transporter SMc02724 (SmYiiP) in Sinorhizobium meliloti: Roles in manganese homeostasis and nodulation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:3203-11. [PMID: 25242380 DOI: 10.1016/j.bbamem.2014.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 09/11/2014] [Accepted: 09/12/2014] [Indexed: 01/29/2023]
Abstract
In bacteria, membrane transporters of the cation diffusion facilitator (CDF) family participate in Zn(2+), Fe(2+), Mn(2+), Co(2+) and Ni(2+) homeostasis. The functional role during infection processes for several members has been shown to be linked to the specificity of transport. Sinorhizobium meliloti has two homologous CDF genes with unknown transport specificity. Here we evaluate the role played by the CDF SMc02724 (SmYiiP). The deletion mutant strain of SmYiiP (ΔsmyiiP) showed reduced in vitro growth fitness only in the presence of Mn(2+). Incubation of ΔsmyiiP and WT cells with sub-lethal Mn(2+) concentrations resulted in a 2-fold increase of the metal only in the mutant strain. Normal levels of resistance to Mn(2+) were attained by complementation with the gene SMc02724 under regulation of its endogenous promoter. In vitro, liposomes with incorporated heterologously expressed pure protein accumulated several transition metals. However, only the transport rate of Mn(2+) was increased by imposing a transmembrane H(+) gradient. Nodulation assays in alfalfa plants showed that the strain ΔsmyiiP induced a lower number of nodules than in plants infected with the WT strain. Our results indicate that Mn(2+) homeostasis in S. meliloti is required for full infection capacity, or nodule function, and that the specificity of transport in vivo of SmYiiP is narrowed down to Mn(2+) by a mechanism involving the proton motive force.
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Affiliation(s)
- Daniel Raimunda
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina.
| | - Graciela Elso-Berberián
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
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Cubillas C, Vinuesa P, Tabche ML, Dávalos A, Vázquez A, Hernández-Lucas I, Romero D, García-de los Santos A. The cation diffusion facilitator protein EmfA of Rhizobium etli belongs to a novel subfamily of Mn(2+)/Fe(2+) transporters conserved in α-proteobacteria. Metallomics 2014; 6:1808-15. [PMID: 25054342 DOI: 10.1039/c4mt00135d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Manganese (Mn(2+)) plays a key role in important cellular functions such as oxidative stress response and bacterial virulence. The mechanisms of Mn(2+) homeostasis are not fully understood, there are few data regarding the functional and taxonomic diversity of Mn(2+) exporters. Our recent phylogeny of the cation diffusion facilitator (CDF) family of transporters classified the bacterial Mn(2+)-CDF transporters characterized to date, Streptococcus pneumoniae MntE and Deinococcus radiodurans DR1236, into two monophyletic groups. DR1236 was shown to belong to the highly-diverse metal specificity clade VI, together with TtCzrB, a Zn(2+)/Cd(2+) transporter from Thermus thermophilus, the Fe(2+) transporter Sll1263 from Synechocystis sp and eight uncharacterized homologs whose potential Mn(2+)/Zn(2+)/Cd(2+)/Fe(2+) specificities could not be accurately inferred because only eleven proteins were grouped in this clade. A new phylogeny inferred from the alignment of 197 clade VI homologs revealed three novel subfamilies of uncharacterized proteins. Remarkably, one of them contained 91 uncharacterized α-proteobacteria transporters (46% of the protein data set) grouped into a single subfamily. The Mn(2+)/Fe(2+) specificity of this subfamily was proposed through the functional characterization of the Rhizobium etli RHE_CH03072 gene. This gene was upregulated by Mn(2+), Zn(2+), Cd(2+) and Fe(2+) but conferred only Mn(2+) resistance to R. etli. The expression of the RHE_CH03072 gene in an E. coli mntP/zitB/zntA mutant did not relieve either Zn(2+) or Mn(2+) stress but slightly increased its Fe(2+) resistance. These results indicate that the RHE_CH03072 gene, now designated as emfA, encodes for a bacterial Mn(2+)/Fe(2+) resistance CDF protein, having orthologs in more than 60 α-proteobacterial species.
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Affiliation(s)
- Ciro Cubillas
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, México.
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26
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Jiang HB, Lou WJ, Ke WT, Song WY, Price NM, Qiu BS. New insights into iron acquisition by cyanobacteria: an essential role for ExbB-ExbD complex in inorganic iron uptake. ISME JOURNAL 2014; 9:297-309. [PMID: 25012898 DOI: 10.1038/ismej.2014.123] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 06/09/2014] [Accepted: 06/12/2014] [Indexed: 01/12/2023]
Abstract
Cyanobacteria are globally important primary producers that have an exceptionally large iron requirement for photosynthesis. In many aquatic ecosystems, the levels of dissolved iron are so low and some of the chemical species so unreactive that growth of cyanobacteria is impaired. Pathways of iron uptake through cyanobacterial membranes are now being elucidated, but the molecular details are still largely unknown. Here we report that the non-siderophore-producing cyanobacterium Synechocystis sp. PCC 6803 contains three exbB-exbD gene clusters that are obligatorily required for growth and are involved in iron acquisition. The three exbB-exbDs are redundant, but single and double mutants have reduced rates of iron uptake compared with wild-type cells, and the triple mutant appeared to be lethal. Short-term measurements in chemically well-defined medium show that iron uptake by Synechocystis depends on inorganic iron (Fe') concentration and ExbB-ExbD complexes are essentially required for the Fe' transport process. Although transport of iron bound to a model siderophore, ferrioxamine B, is also reduced in the exbB-exbD mutants, the rate of uptake at similar total [Fe] is about 800-fold slower than Fe', suggesting that hydroxamate siderophore iron uptake may be less ecologically relevant than free iron. These results provide the first evidence that ExbB-ExbD is involved in inorganic iron uptake and is an essential part of the iron acquisition pathway in cyanobacteria. The involvement of an ExbB-ExbD system for inorganic iron uptake may allow cyanobacteria to more tightly maintain iron homeostasis, particularly in variable environments where iron concentrations range from limiting to sufficient.
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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, Hubei, People's Republic of China
| | - Wen-Jing Lou
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Hubei, People's Republic of China
| | - Wen-Ting Ke
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Hubei, People's Republic of China
| | - Wei-Yu Song
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Hubei, People's Republic of China
| | - Neil M Price
- Department of Biology, McGill University, Montreal, Québec, Canada
| | - Bao-Sheng Qiu
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Hubei, People's Republic of China
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Essential roles of iron superoxide dismutase in photoautotrophic growth of Synechocystis sp. PCC 6803 and heterogeneous expression of marine Synechococcus sp. CC9311 copper/zinc superoxide dismutase within its sodB knockdown mutant. Microbiology (Reading) 2014; 160:228-241. [DOI: 10.1099/mic.0.073080-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Synechocystis sp. PCC 6803 possesses only one sod gene, sodB, encoding iron superoxide dismutase (FeSOD). It could not be knocked out completely by direct insertion of the kanamycin resistance cassette. When the promoter of sodB in WT Synechocystis was replaced with the copper-regulated promoter PpetE, a completely segregated PpetE–sodB strain could be obtained. When this strain was cultured in copper-starved BG11 medium, the chlorophyll a content was greatly reduced, growth was seriously inhibited and the strain was nearly dead during the 8 days of growth, whilst the WT strain grew well under the same growth conditions. These results indicated that sodB was essential for photoautotrophic growth of Synechocystis. The reduction of sodB gene copies in the Synechocystis genome rendered the cells more sensitive to oxidative stress produced by methyl viologen and norflurazon. sodB still could not be knocked out completely after active expression of sodC (encoding Cu/ZnSOD) from Synechococcus sp. CC9311 in the neutral site slr0168 under the control of the psbAII promoter, which means the function of FeSOD could not be complemented completely by Cu/ZnSOD. Heterogeneously expressed sodC increased the oxidation and photoinhibition tolerance of the Synechocystis sodB knockdown mutant. Membrane fractionation followed by immunoblotting revealed that FeSOD was localized in the cytoplasm, and Cu/ZnSOD was localized in the soluble and thylakoid membrane fractions of the transformed Synechocystis. Cu/ZnSOD has a predicted N-terminal signal peptide, so it is probably a lumen protein. The different subcellular localization of these two SODs may have resulted in the failure of substitution of sodC for sodB.
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Cubillas C, Vinuesa P, Tabche ML, García-de los Santos A. Phylogenomic analysis of Cation Diffusion Facilitator proteins uncovers Ni2+/Co2+ transporters. Metallomics 2013; 5:1634-43. [PMID: 24077251 DOI: 10.1039/c3mt00204g] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The ubiquitous Cation Diffusion Facilitator proteins (CDF) play a key role in maintaining the cellular homeostasis of essential metal ions. Previous neighbor-joining phylogenetic analysis classified CDF proteins into three substrate-defined groups: Zn(2+), Fe(2+)/Zn(2+) and Mn(2+). These studies were unable to discern substrate-defined clades for Ni(2+), Co(2+), Cd(2+) and Cu(2+) transporters, despite their existence in this family. In this study we improved the accuracy of this previous functional classification using a phylogenomic approach based on a thorough maximum-likelihood phylogeny and the inclusion of recently characterized CDF transporters. The inference of CDF protein function predicted novel clades for Zn(2+), Fe(2+), Cd(2+) and Mn(2+). The Ni(2+)/Co(2+) and Co(2+) substrate specificities of two clades containing uncharacterized proteins were defined through the functional characterization of nepA and cepA metal inducible genes which independently conferred Ni(2+) and Co(2+) resistances to Rhizobium etli CFN42 and increased, respectively, Ni(2+)/Co(2+) and Co(2+) resistances to Escherichia coli. Neither NepA nor CepA confer Zn(2+), Fe(2+) and Mn(2+) resistances. The ability of NepA to confer Ni(2+)/Co(2+) resistance is dependent on clade-specific residues Asn(88) and Arg(197) whose mutations produce a non-functional protein.
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Affiliation(s)
- Ciro Cubillas
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, México.
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Jiang HB, Cheng HM, Gao KS, Qiu BS. Inactivation of Ca(2+)/H(+) exchanger in Synechocystis sp. strain PCC 6803 promotes cyanobacterial calcification by upregulating CO(2)-concentrating mechanisms. Appl Environ Microbiol 2013; 79:4048-55. [PMID: 23624472 PMCID: PMC3697565 DOI: 10.1128/aem.00681-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 04/19/2013] [Indexed: 11/20/2022] Open
Abstract
Cyanobacteria are important players in the global carbon cycle, accounting for approximately 25% of global CO2 fixation. Their CO2-concentrating mechanisms (CCMs) are thought to play a key role in cyanobacterial calcification, but the mechanisms are not completely understood. In Synechocystis sp. strain PCC 6803, a single Ca(2+)/H(+) exchanger (Slr1336) controls the Ca(2+)/H(+) exchange reaction. We knocked out the exchanger and investigated the effects on cyanobacterial calcification and CCMs. Inactivation of slr1336 significantly increased the calcification rate and decreased the zeta potential, indicating a relatively stronger Ca(2+)-binding ability. Some genes encoding CCM-related components showed increased expression levels, including the cmpA gene, which encodes the Ca(2+)-dependent HCO3(-) transporter BCT1. The transcript level of cmpA in the mutant was 30 times that in wild type. A Western blot analysis further confirmed that protein levels of CmpA were higher in the mutant than the wild type. Measurements of inorganic carbon fluxes and O2 evolution proved that both the net HCO3(-) uptake rate and the BCT1 transporter supported photosynthetic rate in the slr1336 mutant were significantly higher than in the wild type. This would cause the mutant cells to liberate more OH(-) ions out of the cell and stimulate CaCO3 precipitation in the microenvironment. We conclude that the mutation of the Ca(2+)/H(+) exchanger in Synechocystis promoted the cyanobacterial calcification process by upregulating CCMs, especially the BCT1 HCO3(-) transporter. These results shed new light on the mechanism by which CCM-facilitated photosynthesis promotes cyanobacterial calcification.
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Affiliation(s)
- Hai-Bo Jiang
- College of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, People's Republic of China
| | - Hui-Min Cheng
- College of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, People's Republic of China
| | - Kun-Shan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Bao-Sheng Qiu
- College of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, People's Republic of China
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Wang XQ, Jiang HB, Zhang R, Qiu BS. Inactivation of thepetEgene encoding plastocyanin causes different photosynthetic responses in cyanobacteriumSynechocystisPCC 6803 under light-dark photoperiod and continuous light conditions. FEMS Microbiol Lett 2013; 341:106-14. [DOI: 10.1111/1574-6968.12101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Revised: 02/01/2013] [Accepted: 02/06/2013] [Indexed: 12/01/2022] Open
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