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Li B, Zhang X, Wu G, Qin B, Tefsen B, Wells M. Toxins from harmful algal blooms: How copper and iron render chalkophore a predictor of microcystin production. WATER RESEARCH 2023; 244:120490. [PMID: 37659180 DOI: 10.1016/j.watres.2023.120490] [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: 05/24/2023] [Revised: 07/17/2023] [Accepted: 08/13/2023] [Indexed: 09/04/2023]
Abstract
Research on harmful algal blooms has focused on macronutrients, yet recent research increasingly indicates that understanding micronutrient roles is also important in the development of effective environmental management interventions. Here, we report results on metallophore production from mesocosms amended with copper and iron (enzymatic co-factors in photosynthetic electron transport) to probe questions of how cyanobacteria navigate the divide between copper nutrition, copper toxicity, and issues with iron bioavailability. These experiments utilized Microcystis, Chlorella and Desmodesmus spp., in mono- and mixed-cultures in lake water from a large, hypereutrophic lake (Taihu, China). To initiate experiments, copper and iron amendments were added to mesocosms containing algae that had been acclimated to achieve a state of copper and iron limitation. Mesocosms were analyzed over time for a range of analytes including algal growth parameters, algal assemblage progression, copper/iron concentrations and biomolecule production of chalkophore, siderophore and total microcystins. Community Trajectory Analysis and other multivariate methods were used for analysis resulting in our findings: 1) Microcystis spp. manage copper/iron requirements though a dynamically phased behavior of chalkophore/siderophore production according to their copper and iron limitation status (chalkophore correlates with Cu concentration, R2 = 0.99, and siderophore correlates with the sum of Cu and Fe concentrations, R2 = 0.98). 2) A strong correlation was observed between the production of chalkophore and the cyanobacterial toxin microcystin (R2 = 0.76)-Chalkophore is a predictor of microcystin production. 3) Based on our results and literature, we posit that Microcystis spp. produces microcystin in response to copper/iron availability to manage photosystem productivity and effect an energy-saving status. Results from this work underscore the importance of micronutrients in influencing harmful algal bloom progression and represents a major advance in understanding the ecological function for the cyanobacterial toxin microcystin as a hallmark of micronutrient limitation stress.
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Affiliation(s)
- Boling Li
- School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, Jiangsu, 215123, China
| | - Xiaokai Zhang
- Institute of Environmental Processes and Pollution Control, and School of Environmental and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Gongjie Wu
- Department of Biochemistry and Systems Biology, University of Liverpool, Brownlow Hill, Liverpool, L69 7ZX, UK; Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu, 215123, China
| | - Boqiang Qin
- Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Boris Tefsen
- Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands; Ronin Institute, 127 Haddon Place, Montclair, NJ, 07043, USA.
| | - Mona Wells
- Ronin Institute, 127 Haddon Place, Montclair, NJ, 07043, USA; Meadows Center for Water and the Environment, Texas State University, San Marcos, Texas, 78666, USA.
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In Silico and In Vitro Analysis of MAP3773c Protein from Mycobacterium avium subsp. Paratuberculosis. BIOLOGY 2022; 11:biology11081183. [PMID: 36009811 PMCID: PMC9405291 DOI: 10.3390/biology11081183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/29/2022] [Accepted: 08/03/2022] [Indexed: 12/02/2022]
Abstract
Simple Summary Paratuberculosis is a disease that is caused by Mycobacterium avium subsp. paratuberculosis, a bacterium that survives inside a cell to cause disease. This bacterium therefore needs the nutrients of the cell to survive. Zinc and iron are very important elements in its nutrition and are necessary to carry out many of its survival functions, so the cell develops mechanisms to eliminate these pathogenic bacteria to continue living. One of these mechanisms is the elimination of iron as a strategy to kill the bacteria. In this research, we took on the task of studying one of the proteins of the bacterium called MAP3773c, along with its structure, some of its properties and its particular characteristics. In relation to the affinity for zinc and iron to bind to it, we are interested in discovering and making it known to the scientific community whether MAP3773c is related to the pathology of the disease. Abstract Paratuberculosis is a disease caused by Mycobacterium avium subsp. paratuberculosis (MAP). It is of great interest to better understand the proteins involved in the pathogenicity of this organism in order to be able to identify potential therapeutic targets and design new vaccines. The protein of interest–MAP3773c–was investigated, and molecular modeling in silico, docking, cloning, expression, purification, and partial characterization of the recombinant protein were achieved. In the in silico study, it was shown that MAP3773c of MAP has 34% sequence similarity with Mycobacterium tuberculosis (MTB) FurB, which is a zinc uptake regulator (Zur) protein. The docking data showed that MAP3773c exhibits two metal-binding sites. The presence of structural Zn2+ in the purified protein was confirmed by SDS-PAGE PAR staining. The purification showed one band that corresponded to a monomer, which was confirmed by liquid chromatography–mass spectrometry (LC-MS). The presence of a monomer was verified by analyzing the native protein structure through BN-SDS-PAGE (Native Blue (BN) Two-Dimensional Electrophoresis) and BN–Western blotting. The MAP3773c protein contains structural zinc. In conclusion, our results show that MAP3773c displays the features of a Fur-type protein with two metal-binding sites, one of them coordinating structural Zn2+.
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Liu J, Chen L, Zhang X. Current research scenario for biological effect of exogenous factors on microcystin synthesis. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:26190-26201. [PMID: 35089514 DOI: 10.1007/s11356-021-18256-x] [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: 09/08/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
In natural water bodies, numerous cyanobacteria have the potential to intracellularly synthesize cyanotoxins, among which microcystin (MC) is the ubiquitous toxin that has been well known to be carcinogenic for hepatocytes. MC synthesis is a complex process, which involves about 10 non-ribosomal proteins encoded by the mcy gene cluster. In the natural environments containing MC-producing cyanobacteria, a variety of external factors can affect the generation of MC by mediating the expression of synthesizing genes. These factors can be generally divided into biotic factors (e.g., daphnia, virioplankton, MC-degrading bacteria, algicidal bacteria) and abiotic factors (e.g., nutrients, physical factors, chemicals, phytochemicals, essential trace elements), which are of great significance to the effective reduction of MC. Furthermore, comparison of MC-synthesizing genes in different cyanobacterial strains was performed, and the related factors affecting MC synthesis were summarized. Then, the problems and gaps regarding the biological effect of exogenous factors on microcystin synthesis were discussed. This review article may provide new ideas for addressing the challenges and bottlenecks of MC management.
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Affiliation(s)
- Jiahui Liu
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, China
| | - Lv Chen
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, China
| | - Xian Zhang
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, China.
- Hunan Provincial Key Laboratory of Clinical Epidemiology, Central South University, Changsha, China.
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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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Omidi A, Esterhuizen-Londt M, Pflugmacher S. Still challenging: the ecological function of the cyanobacterial toxin microcystin – What we know so far. TOXIN REV 2017. [DOI: 10.1080/15569543.2017.1326059] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Azam Omidi
- Institute of Biotechnology, Chair Ecological Impact Research and Ecotoxicology, Technische Universität Berlin, Berlin, Germany and
| | - Maranda Esterhuizen-Londt
- Institute of Biotechnology, Chair Ecological Impact Research and Ecotoxicology, Technische Universität Berlin, Berlin, Germany and
| | - Stephan Pflugmacher
- Institute of Biotechnology, Chair Ecological Impact Research and Ecotoxicology, Technische Universität Berlin, Berlin, Germany and
- Joint laboratory of Applied Ecotoxicology, Korea Institute of Science and Technology Europe (KIST), Saarbrücken, Germany
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Ceballos-Laita L, Marcuello C, Lostao A, Calvo-Begueria L, Velazquez-Campoy A, Bes MT, Fillat MF, Peleato ML. Microcystin-LR Binds Iron, and Iron Promotes Self-Assembly. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:4841-4850. [PMID: 28368104 DOI: 10.1021/acs.est.6b05939] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The microcystin-producing Microcystis aeruginosa PCC 7806 and its close strain, the nonproducing Microcystis aeruginosa PCC 7005, grow similarly in the presence of 17 μM iron. Under severe iron deficient conditions (0.05 μM), the toxigenic strain grows slightly less than in iron-replete conditions, while the nonproducing microcystin strain is not able to grow. Isothermal titration calorimetry performed at cyanobacterial cytosol or meaningful environmental pHs values shows a microcystin-LR dissociaton constant for Fe2+ and Fe3+ of 2.4 μM. Using atomic force microscopy, 40% of microcystin-LR dimers were observed, and the presence of iron promoted its oligomerization up to six units. Microcystin-LR binds also Mo6+, Cu2+, and Mn2+. Polymeric microcystin binding iron may be related with a toxic cell colony advantage, providing enhanced iron bioavailability and perhaps affecting the structure of the gelatinous sheath. Inside cells, with microcystin implicated in the fitness of the photosynthetic machinery under stress conditions, the toxin would be involved in avoiding metal-dependent Fenton reactions when photooxidation causes disassembly of the iron-rich photosystems. Additionally, it could be hypothesized that polymerization-depolymerization dynamics may be an additional signal that could trigger changes (for example, in the binding of microcystin to proteins).
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Affiliation(s)
- Laura Ceballos-Laita
- Institute for Biocomputation and Physics of Complex Systems (BIFI)-Joint Unit BIFI-IQFR (CSIC) , Aragón 50018, Spain
| | | | | | - Laura Calvo-Begueria
- Institute for Biocomputation and Physics of Complex Systems (BIFI)-Joint Unit BIFI-IQFR (CSIC) , Aragón 50018, Spain
| | - Adrián Velazquez-Campoy
- Institute for Biocomputation and Physics of Complex Systems (BIFI)-Joint Unit BIFI-IQFR (CSIC) , Aragón 50018, Spain
| | - María Teresa Bes
- Institute for Biocomputation and Physics of Complex Systems (BIFI)-Joint Unit BIFI-IQFR (CSIC) , Aragón 50018, Spain
| | - María F Fillat
- Institute for Biocomputation and Physics of Complex Systems (BIFI)-Joint Unit BIFI-IQFR (CSIC) , Aragón 50018, Spain
| | - María-Luisa Peleato
- Institute for Biocomputation and Physics of Complex Systems (BIFI)-Joint Unit BIFI-IQFR (CSIC) , Aragón 50018, Spain
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7
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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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8
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Gehringer MM, Wannicke N. Climate change and regulation of hepatotoxin production in Cyanobacteria. FEMS Microbiol Ecol 2014; 88:1-25. [PMID: 24490596 DOI: 10.1111/1574-6941.12291] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/20/2014] [Accepted: 01/20/2014] [Indexed: 01/04/2023] Open
Abstract
Harmful, bloom-forming cyanobacteria (CyanoHABs) are occurring with increasing regularity in freshwater and marine ecosystems. The most commonly occurring cyanobacterial toxins are the hepatotoxic microcystin and nodularin. These cyclic hepta- and pentapeptides are synthesised nonribosomally by the gene products of the toxin gene clusters mcy and nda, respectively. Understanding of the regulation of hepatotoxin production is incomplete, although there is strong evidence supporting the roles of iron, light, higher nitrate availability and inorganic carbon in modulating microcystin levels. The majority of these studies have focused on the unicellular freshwater, microcystin-producing strain of Microcystis aeruginosa, with little attention being paid to terrestrial or marine toxin producers. This review intends to investigate the regulation of microcystin and nodularin production in unicellular and filamentous diazotrophic cyanobacteria against the background of changing climate conditions. Special focus is given to diazotrophic filamentous cyanobacteria, for example Nodularia spumigena, capable of regulating their nitrogen levels by actively fixing dinitrogen. By combining data from significant studies, an overall scheme of the regulation of toxin production is presented, focussing specifically on nodularin production in diazotrophs against the background of increasing carbon dioxide concentrations and temperatures envisaged under current climate change models. Furthermore, the risk of sustaining and spreading CyanoHABs in the future ocean is evaluated.
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Affiliation(s)
- Michelle M Gehringer
- Department of Plant Ecology and Systematics, Technical University of Kaiserslautern, Kaiserslautern, Germany
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9
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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: 196] [Impact Index Per Article: 19.6] [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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10
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Kuniyoshi TM, Sevilla E, Bes MT, Fillat MF, Peleato ML. Phosphate deficiency (N/P 40:1) induces mcyD transcription and microcystin synthesis in Microcystis aeruginosa PCC7806. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 65:120-124. [PMID: 23481586 DOI: 10.1016/j.plaphy.2013.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 01/15/2013] [Indexed: 06/01/2023]
Abstract
A real-time RT-PCR analysis of the transcriptional response to phosphate availability of the mcyD gene and microcystin-LR synthesis in Microcystis aeruginosa PCC7806 revealed that no significant changes were observed in the relative quantification of mcyD under excess phosphate (N/P = 1:1), whereas in deficiency of this nutrient (N/P = 40:1), a steady increase of mcyD during the exponential growth phase was detected, showing a maximal level on the 7th day of growth with a 6.8-fold increase over the control cells. The microcystin content in phosphate deficient cells correlates with the trend of mcyD transcription observed. Also, in this work we demonstrate that under phosphate deficiency conditions with a ratio of 40:1 N/P, the growth of M. aeruginosa PCC7806 was not affected when compared to control and phosphate excess samples. When blooms occur, the nutrients become exhausted and therefore phosphate availability will be scarce. In such a complex scenario, microcystin synthesis could be a response to phosphate deficiency, among other stress parameters.
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Affiliation(s)
- Taís M Kuniyoshi
- Departamento de Bioquimica y Biologia Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
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11
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Jin MM, Wang P, Li X, Zhao XY, Xu L, Song P, Zhu GP. Biochemical characterization of NADP⁺-dependent isocitrate dehydrogenase from Microcystis aeruginosa PCC7806. Mol Biol Rep 2012; 40:2995-3002. [PMID: 23264072 DOI: 10.1007/s11033-012-2371-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 12/17/2012] [Indexed: 11/30/2022]
Abstract
Microcystis aeruginosa is the key symptom of water eutrophication and produces persistent microcystins. Our special attention was paid to the isocitrate dehydrogenase (IDH) of M. aeruginosa (MaIDH) because it plays important roles in energy and biosynthesis metabolisms and its catalytic product 2-oxoglutarate provides the carbon skeleton for ammonium assimilation and also constitutes a signaling molecule of nitrogen starvation in cyanobacteria. Sequence alignment showed that MaIDH shared significant sequence identity with IDHs from other cyanobacteria (>80 %) and other bacteria (>45 %). The subunit molecular weight of MaIDH was determined to be 52.6 kDa by filtration chromatography, suggesting MaIDH is a typical homodimer. The purified recombinant MaIDH was completely NADP(+)-dependent and no NAD(+)-linked activity was detectable. The K m values for NADP(+) were 32.24 and 71.71 μM with Mg(2+) and Mn(2+) as a sole divalent cation, and DL-isocitrate linked K m values were 32.56 μM (Mg(2+)) and 124.3 μM (Mn(2+)), respectively. As compared with Mn(2+), MaIDH showed about 2.5-times and 4-times higher affinities (1/K m) to NADP(+) and DL-isocitrate with Mg(2+). The optimum activity of MaIDH was found at pH 7.5, and its optimum temperature was 45 °C (Mn(2+)) and 50 °C (Mg(2+)). Heat-inactivation studies showed that heat treatment for 20 min at 45 °C caused a 50 % loss of enzyme activity. MaIDH was completely divalent cation dependent as other typical dimeric IDHs and Mn(2+) was its best activator. Our study is expected to give a better understanding of primary metabolic enzymes in M. aeruginosa. This would provide useful basic information for the research of controlling the blue-green algae blooms through biological techniques.
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Affiliation(s)
- Ming-Ming Jin
- Key Laboratory of Molecular Evolution and Biodiversity and Institute of Molecular Biology and Biotechnology, College of Life Sciences, Anhui Normal University, No.1 Beijing East Road, Wuhu 241000, Anhui, People's Republic of China
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12
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González A, Bes MT, Valladares A, Peleato ML, Fillat MF. FurA is the master regulator of iron homeostasis and modulates the expression of tetrapyrrole biosynthesis genes inAnabaenasp. PCC 7120. Environ Microbiol 2012; 14:3175-87. [DOI: 10.1111/j.1462-2920.2012.02897.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 09/06/2012] [Accepted: 09/09/2012] [Indexed: 12/15/2022]
Affiliation(s)
| | | | - Ana Valladares
- Instituto de Bioquímica Vegetal y Fotosíntesis; Centro de Investigaciones Científicas Isla de la Cartuja; CSIC-Universidad de Sevilla; E-41092; Seville; Spain
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Gupta V, Prasanna R. WITHDRAWN: Cyanobacterial bioactive molecules - Biosynthesis and genetic regulation. Microbiol Res 2012:S0944-5013(12)00091-2. [PMID: 23031424 DOI: 10.1016/j.micres.2012.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Revised: 07/07/2012] [Accepted: 07/09/2012] [Indexed: 10/27/2022]
Abstract
This article has been withdrawn at the request of the editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
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Affiliation(s)
- Vishal Gupta
- Division of Microbiology, Indian Agricultural Research Institute (IARI), New Delhi 110012, India
| | - Radha Prasanna
- Division of Microbiology, Indian Agricultural Research Institute (IARI), New Delhi 110012, India.
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14
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Sevilla E, Martin-Luna B, Bes MT, Fillat MF, Peleato ML. An active photosynthetic electron transfer chain required for mcyD transcription and microcystin synthesis in Microcystis aeruginosa PCC7806. ECOTOXICOLOGY (LONDON, ENGLAND) 2012; 21:811-819. [PMID: 22193542 DOI: 10.1007/s10646-011-0842-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/07/2011] [Indexed: 05/31/2023]
Abstract
In this study, quantitative real time RT-PCR has been used to monitor changes in the levels of transcripts encoding mcyD in Microcystis aeruginosa PCC7806 under oxidative agents and different conditions of light intensity. Microcystin content has also been determined in the same stressed cell aliquots. Our results corroborate the fact that changes in light intensities are able to induce mcyD gene transcription, but our data show that this is an early and short-term event. mcyD transcription requires an active photosynthetic electron transfer chain and the increased transcript level as a consequence of light is not related to oxidative stress. Indeed, oxidative stress leads to a general trend of a decrease of mcyD trancript. Microcystin amount found in the cells follows a tendency consistent with the mcyD transcript level. In summary, the data indicate that the synthesis of microcystin is dependent on photosynthesis, and also show that oxidative stress decreases the microcystin synthesis in toxigenic Microcystis.
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Affiliation(s)
- Emma Sevilla
- Departamento de Bioquimica y Biologia Molecular y Celular, Facultad de Ciencias, and BIFI, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
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15
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Sevilla E, Martín-Luna B, González A, Gonzalo-Asensio JA, Peleato ML, Fillat MF. Identification of three novel antisense RNAs in the fur locus from unicellular cyanobacteria. Microbiology (Reading) 2011; 157:3398-3404. [DOI: 10.1099/mic.0.048231-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The interplay between Fur (ferric uptake regulator) proteins and small, non-coding RNAs has been described as a key regulatory loop in several bacteria. In the filamentous cyanobacterium Anabaena sp. PCC 7120, a large dicistronic transcript encoding the putative membrane protein Alr1690 and an α-furA RNA is involved in the modulation of the global regulator FurA. In this work we report the existence of three novel antisense RNAs in cyanobacteria and show that a cis α-furA RNA is conserved in very different genomic contexts, namely in the unicellular cyanobacteria Microcystis aeruginosa PCC 7806 and Synechocystis sp. PCC 6803. Syα-fur RNA covers only part of the coding sequence of the fur orthologue sll0567, whose flanking genes encode two hypothetical proteins. Transcriptional analysis of fur and its adjacent genes in Microcystis unravels a highly compact organization of this locus involving overlapping transcripts. Maα-fur RNA spans the whole Mafur CDS and part of the flanking dnaJ and sufE sequences. In addition, Mafur seems to be part of a dicistronic operon encoding this regulator and an α-sufE RNA. These results allow new insights into the transcriptomes of two unicellular cyanobacteria and suggest that in M. aeruginosa PCC 7806, the α-fur and α-sufE RNAs might participate in a regulatory connection between the genes of the dnaJ–fur–sufE locus.
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Affiliation(s)
- Emma Sevilla
- Department of Biochemistry and Molecular and Cell Biology, and Biocomputation and Complex Systems Physics Institute (BiFi), University of Zaragoza, Zaragoza, Spain
| | - Beatriz Martín-Luna
- Department of Biochemistry and Molecular and Cell Biology, and Biocomputation and Complex Systems Physics Institute (BiFi), University of Zaragoza, Zaragoza, Spain
| | - Andrés González
- Department of Biochemistry and Molecular and Cell Biology, and Biocomputation and Complex Systems Physics Institute (BiFi), University of Zaragoza, Zaragoza, Spain
| | - Jesús A. Gonzalo-Asensio
- Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto Aragonés de Ciencias de la Salud, Zaragoza, Spain
| | - María Luisa Peleato
- Department of Biochemistry and Molecular and Cell Biology, and Biocomputation and Complex Systems Physics Institute (BiFi), University of Zaragoza, Zaragoza, Spain
| | - María F. Fillat
- Department of Biochemistry and Molecular and Cell Biology, and Biocomputation and Complex Systems Physics Institute (BiFi), University of Zaragoza, Zaragoza, Spain
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Iron uptake by toxic and nontoxic strains of Microcystis aeruginosa. Appl Environ Microbiol 2011; 77:7068-71. [PMID: 21841028 DOI: 10.1128/aem.05270-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Iron uptake by microcystin-producing and non-microcystin-producing strains of Microcystis aeruginosa was investigated through short-term uptake assays. Although strain-specific differences were observed, the siderophore-independent Fe uptake kinetics were essentially similar (e.g., maximum uptake rates of 2.0 to 3.3 amol·cell(-1)·h(-1)) for the wild-type toxic strain PCC7806 and a genetically engineered mutant unable to produce microcystin.
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Alexova R, Fujii M, Birch D, Cheng J, Waite TD, Ferrari BC, Neilan BA. Iron uptake and toxin synthesis in the bloom-forming Microcystis aeruginosa under iron limitation. Environ Microbiol 2011; 13:1064-77. [PMID: 21251177 DOI: 10.1111/j.1462-2920.2010.02412.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Toxin production during cyanobacterial blooms poses a significant public health threat in water bodies globally and requires the development of effective bloom management strategies. Previously, synthesis of the hepatotoxin microcystin has been proposed to be regulated by iron availability, but the contribution of the toxin to the adaptation of cyanobacteria to environmental stresses, such as changing light intensity and nutrient limitation, remains unclear. The aim of this study was to compare the iron stress response in toxic and non-toxic strains of Microcystis aeruginosa subjected to moderate and severe iron limitation. The transcription of a number of genes involved in iron uptake, oxidative stress response, toxin synthesis and transcriptional control of these processes was accessed by quantitative real-time PCR (qRT-PCR). The process of adaptation of M. aeruginosa to iron stress was found to be highly dynamic and strain-specific. Toxin production in PCC 7806 increased in an iron-dependent manner and appeared to be regulated by FurA. The inability to produce microcystin, either due to natural mutations in the mcy gene cluster or due to insertional inactivation of mcyH, affected the remodelling of the photosynthetic machinery in iron-stressed cells, the transport of Fe(II) and transcription of the Fur family of transcriptional regulators. The presence of the toxin appears to give an advantage to microcystin-producing cyanobacteria in the early stages of exposure to severe iron stress and may protect the cell from reactive oxygen species-induced damage.
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Affiliation(s)
- Ralitza Alexova
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
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Kurmayer R, Christiansen G. The Genetic Basis of Toxin Production in Cyanobacteria. ACTA ACUST UNITED AC 2009. [DOI: 10.1608/frj-2.1.2] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Baptista MS, Vasconcelos MT. Cyanobacteria Metal Interactions: Requirements, Toxicity, and Ecological Implications. Crit Rev Microbiol 2008; 32:127-37. [PMID: 16893750 DOI: 10.1080/10408410600822934] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The environmental health-related relevance of cyanobacteria is primarily related to their ability to produce a wide range of toxins, which are known to be hazardous to many organisms, including human beings. The occurrence of cyanobacterial blooms has been related to eutrophic surface water. In the bloom-forming process the levels of phosphorus and nitrogen have been well documented but information regarding concentrations of other chemicals (inorganic, organo-metallic, and organic) is still incipient. Several contaminants, like trace metals, elicit a variety of acute and chronic toxicity effects, but cyanobacteria also have the capability to accumulate, detoxify, or metabolize such substances, to some extent. The role of cyanobacterial exudates has been proved a means of both nutrient acquisition and detoxification. In addition, cyanobacteria are effective biological metal sorbents, representing an important sink for metals in aquatic environment. Understanding the fundamental physicochemical mechanisms of trace metal bio-uptake by cyanobacteria in natural systems is a step towards identifying under what conditions cyanobacterial growth is favored and to ascertain the mechanisms by which blooms (and toxin production) are triggered. In this review the cyanobacterial interactions with metals will be discussed, focusing on freshwater systems.
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Affiliation(s)
- Mafalda S Baptista
- Chemistry Department, Faculty of Sciences, University of Porto, Porto, Portugal.
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Sevilla E, Martin-Luna B, Vela L, Bes MT, Fillat MF, Peleato ML. Iron availability affects mcyD expression and microcystin-LR synthesis in Microcystis aeruginosa PCC7806. Environ Microbiol 2008; 10:2476-83. [DOI: 10.1111/j.1462-2920.2008.01663.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hongsthong A, Sirijuntarut M, Prommeenate P, Thammathorn S, Bunnag B, Cheevadhanarak S, Tanticharoen M. Revealing differentially expressed proteins in two morphological forms of Spirulina platensis by proteomic analysis. Mol Biotechnol 2007; 36:123-30. [PMID: 17914191 DOI: 10.1007/s12033-007-0013-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 10/23/2022]
Abstract
Spirulina is distinguished from other cyanobacteria by its spiral morphology; however, this cyanobacterium has frequently been observed with a linear morphology in laboratory and industrial conditions. In our laboratory conditions, the simultaneously presence of the linear and spiral forms has also been observed. In the present study, the two forms of S. platensis C1 were separated and grown as axenic cultures in order to study the proteins that were differentially expressed in the soluble and insoluble protein fractions of the spiral and the linear forms. Two dimensional-differential gel electrophoresis (2D-DIGE) was performed to separate differentially expressed proteins that were subsequently identified by mass spectrometry. The differentially expressed proteins suggested two points. First, the morphological change is possibly induced by various environmental stresses such as oxygen level, carbon dioxide level, nutrient availability, and light. Second, the change of cell-shape might be a result of the change in a cell shape determination mechanism. Thus, this study is the first to show evidence at the protein level that may explain this morphological transformation in Spirulina.
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Affiliation(s)
- Apiradee Hongsthong
- National Center for Genetic Engineering and Biotechnology, 83 Moo8, Thakham, Bangkhuntien, Bangkok 10150, Thailand.
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Martin-Luna B, Sevilla E, Hernandez JA, Bes MT, Fillat MF, Peleato ML. Fur from Microcystis aeruginosa binds in vitro promoter regions of the microcystin biosynthesis gene cluster. PHYTOCHEMISTRY 2006; 67:876-81. [PMID: 16600317 DOI: 10.1016/j.phytochem.2006.02.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 01/31/2006] [Accepted: 02/01/2006] [Indexed: 05/08/2023]
Abstract
Promoter regions of the mcy operon from Microcystis aeruginosa PCC7806, which is responsible for microcystin synthesis in this organism, exhibit sequences that are similar to the sequences recognized by Fur (ferric uptake regulator). This DNA-binding protein is a sensor of iron availability and oxidative stress. In the presence of Fe(2+), a dimer of Fur binds the iron-boxes in their target genes, repressing their expression. When iron is absent the expression of those gene products is allowed. Here, we show that Fur from M. aeruginosa binds in vitro promoter regions of several mcy genes, which suggests that Fur might regulate, among other factors, microcystin synthesis. The binding affinity is increased by the presence of metal and DTT, suggesting a response to iron availability and redox status of the cell.
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Affiliation(s)
- Beatriz Martin-Luna
- Departamento de Bioquimica y Biologia Molecular y Celular, Facultad de Ciencias, and BIFI, Universidad de Zaragoza, Spain
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