1
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Deng D, Meng H, Ma Y, Guo Y, Wang Z, He H, Xie W, Liu JE, Zhang L. The cumulative impact of temperature and nitrogen availability on the potential nitrogen fixation and extracellular polymeric substances secretion by Dolichospermum. HARMFUL ALGAE 2024; 135:102633. [PMID: 38830715 DOI: 10.1016/j.hal.2024.102633] [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: 01/24/2024] [Revised: 04/02/2024] [Accepted: 04/24/2024] [Indexed: 06/05/2024]
Abstract
Nitrogen-fixing cyanobacteria not only cause severe blooms but also play an important role in the nitrogen input processes of lakes. The production of extracellular polymeric substances (EPS) and the ability to fix nitrogen from the atmosphere provide nitrogen-fixing cyanobacteria with a competitive advantage over other organisms. Temperature and nitrogen availability are key environmental factors in regulating the growth of cyanobacteria. In this study, Dolichospermum (formerly known as Anabaena) was cultivated at three different temperatures (10 °C, 20 °C, and 30 °C) to examine the impact of temperature and nitrogen availability on nitrogen fixation capacity and the release of EPS. Initially, confocal laser scanning microscopy (CLSM) and the quantification of heterocysts at different temperatures revealed that lower temperatures (10 °C) hindered the differentiation of heterocysts under nitrogen-deprived conditions. Additionally, while heterocysts inhibited the photosynthetic activity of Dolichospermum, the secretion of EPS was notably affected by nitrogen limitation, particularly at 30 °C. Finally, real-time quantitative polymerase chain reaction (qPCR) was used to measure the expression of nitrogen-utilizing genes (ntcA and nifH) and EPS synthesis-related genes (wzb and wzc). The results indicated that under nitrogen-deprived conditions, the expression of each gene was upregulated, and there was a significant correlation between the upregulation of nitrogen-utilizing and EPS synthesis genes (P < 0.05). Our findings suggested that Dolichospermum responded to temperature variation by affecting the formation of heterocysts, impacting its potential nitrogen fixation capacity. Furthermore, the quantity of EPS released was more influenced by nitrogen availability than temperature. This research enhances our comprehension of interconnections between nitrogen deprivation and EPS production under the different temperatures.
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Affiliation(s)
- Dailan Deng
- School of Environment, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, PR China; Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing 210023, China
| | - Han Meng
- School of Environment, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, PR China; Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing 210023, China
| | - You Ma
- School of Environment, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, PR China; Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing 210023, China
| | - Yongqi Guo
- School of Environment, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, PR China; Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing 210023, China
| | - Zixuan Wang
- School of Environment, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, PR China; Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing 210023, China
| | - Huan He
- School of Environment, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, PR China; Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing 210023, China
| | - Wenming Xie
- School of Environment, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, PR China; Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing 210023, China
| | - Jin-E Liu
- School of Environment, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, PR China; Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing 210023, China.
| | - Limin Zhang
- School of Environment, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, PR China; Green Economy Development Institute, Nanjing University of Finance and Economics, Nanjing 210023, PR China
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2
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Zheng B, Dong P, Zhao T, Deng Y, Li J, Song L, Wang J, Zhou L, Shi J, Wu Z. Strategies for regulating the intensity of different cyanobacterial blooms: Insights from the dynamics and stability of bacterioplankton communities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170707. [PMID: 38325489 DOI: 10.1016/j.scitotenv.2024.170707] [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: 11/29/2023] [Revised: 01/18/2024] [Accepted: 02/03/2024] [Indexed: 02/09/2024]
Abstract
The occurrence of cyanobacterial blooms is increasing in frequency and magnitude due to climate change and human activities, which poses a direct threat to drinking water security. The impacts of abiotic and biotic factors on the development of blooms have been well studied; however, control strategies for different bloom intensities have rarely been explored from the perspective of the dynamics and stability of bacterioplankton communities. Here, a network analysis was used to investigate the interactions and stability of microbial communities during different periods of R. raciborskii bloom in an inland freshwater lake. The abundance and diversity of rare taxa were significantly higher than that of abundant taxa throughout the bloom cycle. At the pre-bloom (PB) stage, microbial interactions among the different bacterial groups were weak but strongly negatively correlated, indicating low robustness and weak disturbance resistance within the community. However, community stability was better, and microbial interactions became more complicated at the high-bloom (HB) and low-bloom (LB) stages. Interestingly, rare taxa were significantly responsible for community stability and connectivity despite their low relative abundance. The Mantel test revealed that Secchi depth (SD), orthophosphate (PO43--P), and dissolved oxygen (DO) were significantly positively correlated with abundant taxa, rare taxa and PB. DO was significantly positively correlated with HB, intermediate taxa, and rare taxa, while water temperature (WT), N/P and total nitrogen (TN) were significantly positively correlated with LB, abundant taxa, intermediate taxa, and rare taxa. These findings suggest that reducing the PO43--P concentration at the PB stage may be an effective approach to preventing the development of R. raciborskii blooms, while regulating rare taxa at the HB and LB stages may be a key factor in controlling R. raciborskii blooms.
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Affiliation(s)
- Baohai Zheng
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Peichang Dong
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Teng Zhao
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Yuting Deng
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Jie Li
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha 410013, China
| | - Lirong Song
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Jinna Wang
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Ling Zhou
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Junqiong Shi
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Zhongxing Wu
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China.
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3
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Xing WY, Liu J, Zhang CC. HetF defines a transition point from commitment to morphogenesis during heterocyst differentiation in the cyanobacterium Anabaena sp. PCC 7120. Mol Microbiol 2023; 120:740-753. [PMID: 37804047 DOI: 10.1111/mmi.15177] [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: 07/27/2023] [Revised: 09/16/2023] [Accepted: 09/22/2023] [Indexed: 10/08/2023]
Abstract
The filamentous cyanobacterium Anabaena sp. PCC 7120 is able to form heterocysts for nitrogen fixation. Heterocyst differentiation is initiated by combined-nitrogen deprivation, followed by the commitment step during which the developmental process becomes irreversible. Mature heterocysts are terminally differentiated cells unable to divide, and cell division is required for heterocyst differentiation. Previously, we have shown that the HetF protease regulates cell division and heterocyst differentiation by cleaving PatU3, which is an inhibitor for both events. When hetF is required during the developmental program remains unknown. Here, by controlling the timing of hetF expression during heterocyst differentiation, we provide evidence that hetF is required just before the beginning of heterocyst morphogenesis. Consistent with this finding, transcriptome data show that most of the genes known to be involved in the early step (such as hetR and ntcA) or the commitment step (such as hetP and hetZ) of heterocyst development could be expressed in the ΔhetF mutant. In contrast, most of the genes involved in heterocyst morphogenesis and nitrogen fixation remain repressed in the mutant. These results indicated that in the absence of hetF, heterocyst differentiation is able to be initiated and proceeds to the stage just before heterocyst envelope formation.
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Affiliation(s)
- Wei-Yue Xing
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China
| | - Jing Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China
| | - Cheng-Cai Zhang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China
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Brenes-Álvarez M, Vioque A, Muro-Pastor AM. Nitrogen-regulated antisense transcription in the adaptation to nitrogen deficiency in Nostoc sp. PCC 7120. PNAS NEXUS 2023; 2:pgad187. [PMID: 37361547 PMCID: PMC10287535 DOI: 10.1093/pnasnexus/pgad187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/24/2023] [Accepted: 05/30/2023] [Indexed: 06/28/2023]
Abstract
Transcriptomic analyses using high-throughput methods have revealed abundant antisense transcription in bacteria. Antisense transcription is often due to the overlap of mRNAs with long 5' or 3' regions that extend beyond the coding sequence. In addition, antisense RNAs that do not contain any coding sequence are also observed. Nostoc sp. PCC 7120 is a filamentous cyanobacterium that, under nitrogen limitation, behaves as a multicellular organism with division of labor among two different cell types that depend on each other, the vegetative CO2-fixing cells and the nitrogen-fixing heterocysts. The differentiation of heterocysts depends on the global nitrogen regulator NtcA and requires the specific regulator HetR. To identify antisense RNAs potentially involved in heterocyst differentiation, we assembled the Nostoc transcriptome using RNA-seq analysis of cells subjected to nitrogen limitation (9 or 24 h after nitrogen removal) in combination with a genome-wide set of transcriptional start sites and a prediction of transcriptional terminators. Our analysis resulted in the definition of a transcriptional map that includes >4,000 transcripts, 65% of which contain regions in antisense orientation to other transcripts. In addition to overlapping mRNAs, we identified nitrogen-regulated noncoding antisense RNAs transcribed from NtcA- or HetR-dependent promoters. As an example of this last category, we further analyzed an antisense (as_gltA) of the gene-encoding citrate synthase and showed that transcription of as_gltA takes place specifically in heterocysts. Since the overexpression of as_gltA reduces citrate synthase activity, this antisense RNA could eventually contribute to the metabolic remodeling that occurs during the differentiation of vegetative cells into heterocysts.
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Affiliation(s)
| | - Agustín Vioque
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Américo Vespucio 49, 41092 Sevilla, Spain
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5
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Satta A, Esquirol L, Ebert BE. Current Metabolic Engineering Strategies for Photosynthetic Bioproduction in Cyanobacteria. Microorganisms 2023; 11:455. [PMID: 36838420 PMCID: PMC9964548 DOI: 10.3390/microorganisms11020455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 02/04/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Cyanobacteria are photosynthetic microorganisms capable of using solar energy to convert CO2 and H2O into O2 and energy-rich organic compounds, thus enabling sustainable production of a wide range of bio-products. More and more strains of cyanobacteria are identified that show great promise as cell platforms for the generation of bioproducts. However, strain development is still required to optimize their biosynthesis and increase titers for industrial applications. This review describes the most well-known, newest and most promising strains available to the community and gives an overview of current cyanobacterial biotechnology and the latest innovative strategies used for engineering cyanobacteria. We summarize advanced synthetic biology tools for modulating gene expression and their use in metabolic pathway engineering to increase the production of value-added compounds, such as terpenoids, fatty acids and sugars, to provide a go-to source for scientists starting research in cyanobacterial metabolic engineering.
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Affiliation(s)
- Alessandro Satta
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD 4072, Australia
- Department of Biology, University of Padua, 35100 Padua, Italy
| | - Lygie Esquirol
- Centre for Cell Factories and Biopolymers, Griffith Institute for Drug Discovery, Griffith University, Natha, QLD 4111, Australia
| | - Birgitta E. Ebert
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD 4072, Australia
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Casanova-Ferrer P, Muñoz-García J, Ares S. Mathematical models of nitrogen-fixing cell patterns in filamentous cyanobacteria. Front Cell Dev Biol 2022; 10:959468. [PMID: 36187490 PMCID: PMC9523125 DOI: 10.3389/fcell.2022.959468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/25/2022] [Indexed: 11/13/2022] Open
Abstract
The Anabaena genus is a model organism of filamentous cyanobacteria whose vegetative cells can differentiate under nitrogen-limited conditions into a type of cell called a heterocyst. These heterocysts lose the possibility to divide and are necessary for the filament because they can fix and share environmental nitrogen. In order to distribute the nitrogen efficiently, heterocysts are arranged to form a quasi-regular pattern whose features are maintained as the filament grows. Recent efforts have allowed advances in the understanding of the interactions and genetic mechanisms underlying this dynamic pattern. Here, we present a systematic review of the existing theoretical models of nitrogen-fixing cell differentiation in filamentous cyanobacteria. These filaments constitute one of the simplest forms of multicellular organization, and this allows for several modeling scales of this emergent pattern. The system has been approached at three different levels. From bigger to smaller scale, the system has been considered as follows: at the population level, by defining a mean-field simplified system to study the ratio of heterocysts and vegetative cells; at the filament level, with a continuous simplification as a reaction-diffusion system; and at the cellular level, by studying the genetic regulation that produces the patterning for each cell. In this review, we compare these different approaches noting both the virtues and shortcomings of each one of them.
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Affiliation(s)
- Pau Casanova-Ferrer
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain
- Departamento de Matemáticas, Universidad Carlos III de Madrid, Leganés, Spain
- Centro Nacional de Biotecnologia (CNB), CSIC, Madrid, Spain
| | - Javier Muñoz-García
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain
- Departamento de Matemáticas, Universidad Carlos III de Madrid, Leganés, Spain
| | - Saúl Ares
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain
- Centro Nacional de Biotecnologia (CNB), CSIC, Madrid, Spain
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A proteolytic pathway coordinates cell division and heterocyst differentiation in the cyanobacterium Anabaena sp. PCC 7120. Proc Natl Acad Sci U S A 2022; 119:e2207963119. [PMID: 36037363 PMCID: PMC9457339 DOI: 10.1073/pnas.2207963119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The filamentous, multicellular cyanobacterium Anabaena sp. PCC 7120 (Anabaena) is a prokaryotic model for the study of cell differentiation and cell-cell interactions. Upon combined-nitrogen deprivation, Anabaena forms a particular cell type, heterocyst, for aerobic nitrogen fixation. Heterocysts are semiregularly spaced among vegetative cells. Heterocyst differentiation is coupled to cell division, but the underlying mechanism remains unclear. This mechanism could be mediated by the putative protease HetF, which is a divisome component and is necessary for heterocyst differentiation. In this study, by suppressor screening, we identified PatU3, as a negative regulator acting downstream of HetF for cell division and heterocyst development. The inactivation of patU3 restored the capacity of cell division and heterocyst differentiation in the ΔhetF mutant, and overexpression of patU3 inhibited both processes in the wild-type background. We demonstrated that PatU3 was a specific substrate of the protease activity of HetF. Consequently, PatU3 accumulated in the hetF-deficient mutant, which was responsible for the resultant mutant phenotype. The cleavage site of PatU3 by HetF was mapped after the Arg117 residue, whose mutation made PatU3 resistant to HetF processing, and mimicked the effect of hetF deletion. Our results provided evidence that HetF regulated cell division and heterocyst differentiation by controlling the inhibitory effects of PatU3. This proteolytic pathway constituted a mechanism for the coordination between cell division and differentiation in a prokaryotic model used for studies on developmental biology and multicellularity.
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To Die or Not to Die—Regulated Cell Death and Survival in Cyanobacteria. Microorganisms 2022; 10:microorganisms10081657. [PMID: 36014075 PMCID: PMC9415839 DOI: 10.3390/microorganisms10081657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/06/2022] [Accepted: 08/12/2022] [Indexed: 11/24/2022] Open
Abstract
Regulated cell death (RCD) is central to the development, integrity, and functionality of multicellular organisms. In the last decade, evidence has accumulated that RCD is a universal phenomenon in all life domains. Cyanobacteria are of specific interest due to their importance in aquatic and terrestrial habitats and their role as primary producers in global nutrient cycling. Current knowledge on cyanobacterial RCD is based mainly on biochemical and morphological observations, often by methods directly transferred from vertebrate research and with limited understanding of the molecular genetic basis. However, the metabolism of different cyanobacteria groups relies on photosynthesis and nitrogen fixation, whereas mitochondria are the central executioner of cell death in vertebrates. Moreover, cyanobacteria chosen as biological models in RCD studies are mainly colonial or filamentous multicellular organisms. On the other hand, unicellular cyanobacteria have regulated programs of cellular survival (RCS) such as chlorosis and post-chlorosis resuscitation. The co-existence of different genetically regulated programs in cyanobacterial populations may have been a top engine in life diversification. Development of cyanobacteria-specific methods for identification and characterization of RCD and wider use of single-cell analysis combined with intelligent image-based cell sorting and metagenomics would shed more light on the underlying molecular mechanisms and help us to address the complex colonial interactions during these events. In this review, we focus on the functional implications of RCD in cyanobacterial communities.
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Casanova-Ferrer P, Ares S, Muñoz-García J. Terminal heterocyst differentiation in the Anabaena patA mutant as a result of post-transcriptional modifications and molecular leakage. PLoS Comput Biol 2022; 18:e1010359. [PMID: 35969646 PMCID: PMC9410556 DOI: 10.1371/journal.pcbi.1010359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 08/25/2022] [Accepted: 07/05/2022] [Indexed: 12/27/2022] Open
Abstract
The Anabaena genus is a model organism of filamentous cyanobacteria whose vegetative cells can differentiate under nitrogen-limited conditions into a type of cell called heterocyst. These heterocysts lose the possibility to divide and are necessary for the colony because they can fix and share environmental nitrogen. In order to distribute the nitrogen efficiently, heterocysts are arranged to form a quasi-regular pattern whose features are maintained as the filament grows. Recent efforts have allowed advances in the understanding of the interactions and genetic mechanisms underlying this dynamic pattern. However, the main role of the patA and hetF genes are yet to be clarified; in particular, the patA mutant forms heterocysts almost exclusively in the terminal cells of the filament. In this work, we investigate the function of these genes and provide a theoretical model that explains how they interact within the broader genetic network, reproducing their knock-out phenotypes in several genetic backgrounds, including a nearly uniform concentration of HetR along the filament for the patA mutant. Our results suggest a role of hetF and patA in a post-transcriptional modification of HetR which is essential for its regulatory function. In addition, the existence of molecular leakage out of the filament in its boundary cells is enough to explain the preferential appearance of terminal heterocysts, without any need for a distinct regulatory pathway. Understanding multicellular pattern formation is key for the study of both natural and synthetic developmental processes. Arguably one of the simplest model systems for this is the filamentous cyanobacterium Anabaena, that in conditions of nitrogen deprivation undergoes a dynamical differentiation process that differentiates roughly one in every ten cells into nitrogen-fixing heterocysts, in a quasi-regular pattern that is maintained as the filament keeps growing. One of the most characteristic mutations affecting this process forms heterocysts mostly constrained to the terminal cells of the filament. We have used experimental observations to propose a mathematical model of heterocyst differentiation able to reproduce this striking phenotype. The model extends our understanding of the regulations in this pattern-forming system and makes several predictions on molecular interactions. Importantly, a key aspect is the boundary condition at the filament’s ends: inhibitors of differentiation should be able to leak out of the filament, or otherwise the terminal cells would not differentiate. This highlights, in a very clear example, the importance of considering physical constraints in developmental processes.
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Affiliation(s)
- Pau Casanova-Ferrer
- Grupo Interdisciplinar de Sistemas Complejos (GISC) and Departamento de Matemáticas, Universidad Carlos III de Madrid, Leganés, Spain
- Centro Nacional de Biotecnologia (CNB), CSIC, Madrid, Spain
| | - Saúl Ares
- Grupo Interdisciplinar de Sistemas Complejos (GISC) and Departamento de Matemáticas, Universidad Carlos III de Madrid, Leganés, Spain
- Centro Nacional de Biotecnologia (CNB), CSIC, Madrid, Spain
- * E-mail: (SA); (JM-G)
| | - Javier Muñoz-García
- Grupo Interdisciplinar de Sistemas Complejos (GISC) and Departamento de Matemáticas, Universidad Carlos III de Madrid, Leganés, Spain
- * E-mail: (SA); (JM-G)
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Xu C, Wang B, Heng H, Huang J, Wan C. Comparative Network Biology Discovers Protein Complexes That Underline Cellular Differentiation in Anabaena sp. Mol Cell Proteomics 2022; 21:100224. [PMID: 35288331 PMCID: PMC9035410 DOI: 10.1016/j.mcpro.2022.100224] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 02/20/2022] [Accepted: 03/10/2022] [Indexed: 01/11/2023] Open
Abstract
The filamentous cyanobacterium Anabaena sp. PCC 7120 can differentiate into heterocysts to fix atmospheric nitrogen. During cell differentiation, cellular morphology and gene expression undergo a series of significant changes. To uncover the mechanisms responsible for these alterations, we built protein–protein interaction (PPI) networks for these two cell types by cofractionation coupled with mass spectrometry. We predicted 280 and 215 protein complexes, with 6322 and 2791 high-confidence PPIs in vegetative cells and heterocysts, respectively. Most of the proteins in both types of cells presented similar elution profiles, whereas the elution peaks of 438 proteins showed significant changes. We observed that some well-known complexes recruited new members in heterocysts, such as ribosomes, diflavin flavoprotein, and cytochrome c oxidase. Photosynthetic complexes, including photosystem I, photosystem II, and phycobilisome, remained in both vegetative cells and heterocysts for electron transfer and energy generation. Besides that, PPI data also reveal new functions of proteins. For example, the hypothetical protein Alr4359 was found to interact with FraH and Alr4119 in heterocysts and was located on heterocyst poles, thereby influencing the diazotrophic growth of filaments. The overexpression of Alr4359 suspended heterocyst formation and altered the pigment composition and filament length. This work demonstrates the differences in protein assemblies and provides insight into physiological regulation during cell differentiation. PPIs in two types of cells of Anabaena sp. 7120 were systematically identified. 10,302 and 8557 high-confidence PPIs were obtained and over 80% were novel. About 438 proteins showed significant changes in vegetative cells and heterocysts. Protein Alr4359 was found to influence the diazotrophic growth of filaments.
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Affiliation(s)
- Chen Xu
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, China
| | - Bing Wang
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, China
| | - Hailu Heng
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, China
| | - Jiangmei Huang
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, China
| | - Cuihong Wan
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, China.
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11
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Zhang JY, Niu TC, Lin GM, Zhang CC. A CRISPR-Based Method for Constructing Conditional Mutations of Essential Genes in Cyanobacteria. Methods Mol Biol 2022; 2377:143-157. [PMID: 34709615 DOI: 10.1007/978-1-0716-1720-5_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Cyanobacteria, a group of diverse bacteria capable of oxygenic photosynthesis, are excellent models for investigating many important cellular processes, such as photosynthesis, nitrogen fixation, and prokaryotic cell differentiation. They also have great potential to become the next-generation cell factories for sustainable biosynthesis of valuable products. However, genetic manipulation in cyanobacteria is not as convenient as in other model bacteria. Particularly, handling essential genes in cyanobacteria has been difficult due to the lack of appropriate tools, limiting our understanding of many important cellular functions encoded by them. We recently develop a CRISPR-based method for constructing the conditional mutants of cyanobacterial essential genes by engineering the ribosome binding site to a theophylline-responsive riboswitch. Here, we provide the details of this method. The principle of this method could be used to construct conditional mutants in a wide range of bacterial species.
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Affiliation(s)
- Ju-Yuan Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province, China.
| | - Tian-Cai Niu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province, China
| | - Gui-Ming Lin
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province, China
| | - Cheng-Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province, China
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12
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Huang M, Zhang JY, Zeng X, Zhang CC. c-di-GMP Homeostasis Is Critical for Heterocyst Development in Anabaena sp. PCC 7120. Front Microbiol 2021; 12:793336. [PMID: 34925302 PMCID: PMC8682488 DOI: 10.3389/fmicb.2021.793336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 11/09/2021] [Indexed: 12/04/2022] Open
Abstract
c-di-GMP is a ubiquitous bacterial signal regulating various physiological process. Anabaena PCC 7120 (Anabaena) is a filamentous cyanobacterium able to form regularly-spaced heterocysts for nitrogen fixation, in response to combined-nitrogen deprivation in 24h. Anabaena possesses 16 genes encoding proteins for c-di-GMP metabolism, and their functions are poorly characterized, except all2874 (cdgS) whose deletion causes a decrease in heterocyst frequency 48h after nitrogen starvation. We demonstrated here that c-di-GMP levels increased significantly in Anabaena after combined-nitrogen starvation. By inactivating each of the 16 genes, we found that the deletion of all1175 (cdgSH) led to an increase of heterocyst frequency 24h after nitrogen stepdown. A double mutant ΔcdgSHΔcdgS had an additive effect over the single mutants in regulating heterocyst frequency, indicating that the two genes acted at different time points for heterocyst spacing. Biochemical and genetic data further showed that the functions of CdgSH and CdgS in the setup or maintenance of heterocyst frequency depended on their opposing effects on the intracellular levels of c-di-GMP. Finally, we demonstrated that heterocyst differentiation was completely inhibited when c-di-GMP levels became too high or too low. Together, these results indicate that the homeostasis of c-di-GMP level is important for heterocyst differentiation in Anabaena.
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Affiliation(s)
- Min Huang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Ju-Yuan Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Xiaoli Zeng
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Cheng-Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China.,Institut AMU-WUT, Aix-Marseille University and Wuhan University of Technology, Wuhan, China.,Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
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13
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Cross-Activation of Two Nitrogenase Gene Clusters by CnfR1 or CnfR2 in the Cyanobacterium Anabaena variabilis. Microbiol Spectr 2021; 9:e0106021. [PMID: 34612667 PMCID: PMC8510180 DOI: 10.1128/spectrum.01060-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Anabaena variabilis, the nif1 genes, which are activated by CnfR1, produce a Mo-nitrogenase that is expressed only in heterocysts. Similarly, the nif2 genes, which are activated by CnfR2, make a Mo-nitrogenase that is expressed only in anaerobic vegetative cells. However, CnfR1, when it was expressed in anaerobic vegetative cells under the control of the cnfR2 promoter or from the Co2+-inducible coaT promoter, activated the expression of both nifB1 and nifB2. Activation of nifB2, but not nifB1, by CnfR1 required NtcA. Thus, expression of the nif1 system requires no heterocyst-specific factor other than CnfR1. In contrast, CnfR2, when it was expressed in heterocysts under the control of the cnfR1 promoter or from the coaT promoter, did not activate the expression of nifB1 or nifB2. Thus, activation of the nif2 system in anaerobic vegetative cells by CnfR2 requires additional factors absent in heterocysts. CnfR2 made from the coaT promoter activated nifB2 expression in anaerobic vegetative cells grown with fixed nitrogen; however, oxygen inhibited CnfR2 activation of nifB2 expression. In contrast, activation of nifB1 and nifB2 by CnfR1 was unaffected by oxygen. CnfR1, which does not activate the nifB2 promoter in heterocysts, activated the expression of the entire nif2 gene cluster from a nifB2::nifB1::nifB2 hybrid promoter in heterocysts, producing functional Nif2 nitrogenase in heterocysts. However, activity was poor compared to the normal Nif1 nitrogenase. Expression of the nif2 cluster in anaerobic vegetative cells of Nostoc sp. PCC 7120, a strain lacking the nif2 nitrogenase, resulted in expression of the nif2 genes but weak nitrogenase activity. IMPORTANCE Cyanobacterial nitrogen fixation is important in the global nitrogen cycle, in oceanic productivity, and in many plant and fungal symbioses. While the proteins that mediate nitrogen fixation have been well characterized, the regulation of this complex and expensive process is poorly understood in cyanobacteria. Using a genetic approach, we have characterized unique and overlapping functions for two homologous transcriptional activators CnfR1 and CnfR2 that activate two distinct nitrogenases in a single organism. We found that CnfR1 is promiscuous in its ability to activate both nitrogenase systems, whereas CnfR2 depends on additional cellular factors; thus, it activates only one nitrogenase system.
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14
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Ranjbar MH, Hamilton DP, Etemad-Shahidi A, Helfer F. Individual-based modelling of cyanobacteria blooms: Physical and physiological processes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 792:148418. [PMID: 34157534 DOI: 10.1016/j.scitotenv.2021.148418] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/20/2021] [Accepted: 06/08/2021] [Indexed: 06/13/2023]
Abstract
Lakes and reservoirs throughout the world are increasingly adversely affected by cyanobacterial harmful algal blooms (CyanoHABs). The development and spatiotemporal distributions of blooms are governed by complex physical mixing and transport processes that interact with physiological processes affecting the growth and loss of bloom-forming species. Individual-based models (IBMs) can provide a valuable tool for exploring and integrating some of these processes. Here we contend that the advantages of IBMs have not been fully exploited. The main reasons for the lack of progress in mainstreaming IBMs in numerical modelling are their complexity and high computational demand. In this review, we identify gaps and challenges in the use of IBMs for modelling CyanoHABs and provide an overview of the processes that should be considered for simulating the spatial and temporal distributions of cyanobacteria. Notably, important processes affecting cyanobacteria distributions, in particular their vertical passive movement, have not been considered in many existing lake ecosystem models. We identify the following research gaps that should be addressed in future studies that use IBMs: 1) effects of vertical movement and physiological processes relevant to cyanobacteria growth and accumulations, 2) effects and feedbacks of CyanoHABs on their environment; 3) inter and intra-specific competition of cyanobacteria species for nutrients and light; 4) use of high resolved temporal-spatial data for calibration and verification targets for IBMs; and 5) climate change impacts on the frequency, intensity and duration of CyanoHABs. IBMs are well adapted to incorporate these processes and should be considered as the next generation of models for simulating CyanoHABs.
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Affiliation(s)
| | - David P Hamilton
- Australian Rivers Institute, Griffith University, QLD 4111, Australia.
| | - Amir Etemad-Shahidi
- School of Engineering and Built Environment, Griffith University, QLD 4222, Australia; School of Engineering, Edith Cowan University, WA 6027, Australia
| | - Fernanda Helfer
- School of Engineering and Built Environment, Griffith University, QLD 4222, Australia
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15
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Brenes-Álvarez M, Olmedo-Verd E, Vioque A, Muro-Pastor AM. A nitrogen stress-inducible small RNA regulates CO2 fixation in Nostoc. PLANT PHYSIOLOGY 2021; 187:787-798. [PMID: 34608966 PMCID: PMC8491059 DOI: 10.1093/plphys/kiab309] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 06/09/2021] [Indexed: 05/09/2023]
Abstract
In the absence of fixed nitrogen, some filamentous cyanobacteria differentiate heterocysts, specialized cells devoted to fixing atmospheric nitrogen (N2). This differentiation process is controlled by the global nitrogen regulator NtcA and involves extensive metabolic reprogramming, including shutdown of photosynthetic CO2 fixation in heterocysts, to provide a microaerobic environment suitable for N2 fixation. Small regulatory RNAs (sRNAs) are major post-transcriptional regulators of gene expression in bacteria. In cyanobacteria, responding to nitrogen deficiency involves transcribing several nitrogen-regulated sRNAs. Here, we describe the participation of nitrogen stress-inducible RNA 4 (NsiR4) in post-transcriptionally regulating the expression of two genes involved in CO2 fixation via the Calvin cycle: glpX, which encodes bifunctional sedoheptulose-1,7-bisphosphatase/fructose-1,6-bisphosphatase (SBPase), and pgk, which encodes phosphoglycerate kinase (PGK). Using a heterologous reporter assay in Escherichia coli, we show that NsiR4 interacts with the 5'-untranslated region (5'-UTR) of glpX and pgk mRNAs. Overexpressing NsiR4 in Nostoc sp. PCC 7120 resulted in a reduced amount of SBPase protein and reduced PGK activity, as well as reduced levels of both glpX and pgk mRNAs, further supporting that NsiR4 negatively regulates these two enzymes. In addition, using a gfp fusion to the nsiR4 promoter, we show stronger expression of NsiR4 in heterocysts than in vegetative cells, which could contribute to the heterocyst-specific shutdown of Calvin cycle flux. Post-transcriptional regulation of two Calvin cycle enzymes by NsiR4, a nitrogen-regulated sRNA, represents an additional link between nitrogen control and CO2 assimilation.
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Affiliation(s)
- Manuel Brenes-Álvarez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Seville E-41092, Spain
| | - Elvira Olmedo-Verd
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Seville E-41092, Spain
| | - Agustín Vioque
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Seville E-41092, Spain
| | - Alicia M. Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Seville E-41092, Spain
- Author for communication:
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16
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Zhang Q, Yu S, Wang Q, Yang M, Ge F. Quantitative Proteomics Reveals the Protein Regulatory Network of Anabaena sp. PCC 7120 under Nitrogen Deficiency. J Proteome Res 2021; 20:3963-3976. [PMID: 34270261 DOI: 10.1021/acs.jproteome.1c00302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Anabaena sp. PCC 7120 (Anabaena 7120) is a photoautotrophic filamentous cyanobacterium capable of fixing atmospheric nitrogen. It is a model organism used for studying cell differentiation and nitrogen fixation. Under nitrogen deficiency, Anabaena 7120 forms specialized heterocysts capable of nitrogen fixation. However, the molecular mechanisms involved in the cyanobacterial adaptation to nitrogen deficiency are not well understood. Here, we employed a label-free quantitative proteomic strategy to systematically investigate the nitrogen deficiency response of Anabaena 7120 at different time points. In total, 363, 603, and 669 proteins showed significant changes in protein abundance under nitrogen deficiency for 3, 12, and 24 h, respectively. With mapping onto metabolic pathways, we revealed proteomic perturbation and regulation of carbon and nitrogen metabolism in response to nitrogen deficiency. Functional analysis confirmed the involvement of nitrogen stress-responsive proteins in biological processes, including nitrogen fixation, photosynthesis, energy and carbon metabolism, and heterocyst development. The expression of 10 proteins at different time points was further validated by using multiple reaction monitoring assays. In particular, many dysregulated proteins were found to be time-specific and involved in heterocyst development, providing new candidates for future functional studies in this model cyanobacterium. These results provide novel insights into the molecular mechanisms of nitrogen stress responses and heterocyst development in Anabaena 7120.
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Affiliation(s)
- Qi Zhang
- College of Fisheries and Life Science, Dalian Ocean University, Dalian 116000, China.,State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.,University of Chinese Academy of Sciences, Beijing 100039, China
| | - Shengchao Yu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.,University of Chinese Academy of Sciences, Beijing 100039, China
| | - Qiang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Mingkun Yang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.,University of Chinese Academy of Sciences, Beijing 100039, China
| | - Feng Ge
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.,University of Chinese Academy of Sciences, Beijing 100039, China
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17
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Sánchez-Romero MA, Casadesús J. Waddington's Landscapes in the Bacterial World. Front Microbiol 2021; 12:685080. [PMID: 34149674 PMCID: PMC8212987 DOI: 10.3389/fmicb.2021.685080] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 04/20/2021] [Indexed: 11/24/2022] Open
Abstract
Conrad Waddington’s epigenetic landscape, a visual metaphor for the development of multicellular organisms, is appropriate to depict the formation of phenotypic variants of bacterial cells. Examples of bacterial differentiation that result in morphological change have been known for decades. In addition, bacterial populations contain phenotypic cell variants that lack morphological change, and the advent of fluorescent protein technology and single-cell analysis has unveiled scores of examples. Cell-specific gene expression patterns can have a random origin or arise as a programmed event. When phenotypic cell-to-cell differences are heritable, bacterial lineages are formed. The mechanisms that transmit epigenetic states to daughter cells can have strikingly different levels of complexity, from the propagation of simple feedback loops to the formation of complex DNA methylation patterns. Game theory predicts that phenotypic heterogeneity can facilitate bacterial adaptation to hostile or unpredictable environments, serving either as a division of labor or as a bet hedging that anticipates future challenges. Experimental observation confirms the existence of both types of strategies in the bacterial world.
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Affiliation(s)
| | - Josep Casadesús
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
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18
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Perin G, Fletcher T, Sagi-Kiss V, Gaboriau DCA, Carey MR, Bundy JG, Jones PR. Calm on the surface, dynamic on the inside. Molecular homeostasis of Anabaena sp. PCC 7120 nitrogen metabolism. PLANT, CELL & ENVIRONMENT 2021; 44:1885-1907. [PMID: 33608943 DOI: 10.1111/pce.14034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 02/12/2021] [Accepted: 02/13/2021] [Indexed: 06/12/2023]
Abstract
Nitrogen sources are all converted into ammonium/ia as a first step of assimilation. It is reasonable to expect that molecular components involved in the transport of ammonium/ia across biological membranes connect with the regulation of both nitrogen and central metabolism. We applied both genetic (i.e., Δamt mutation) and environmental treatments to a target biological system, the cyanobacterium Anabaena sp PCC 7120. The aim was to both perturb nitrogen metabolism and induce multiple inner nitrogen states, respectively, followed by targeted quantification of key proteins, metabolites and enzyme activities. The absence of AMT transporters triggered a substantial whole-system response, affecting enzyme activities and quantity of proteins and metabolites, spanning nitrogen and carbon metabolisms. Moreover, the Δamt strain displayed a molecular fingerprint indicating nitrogen deficiency even under nitrogen replete conditions. Contrasting with such dynamic adaptations was the striking near-complete lack of an externally measurable altered phenotype. We conclude that this species evolved a highly robust and adaptable molecular network to maintain homeostasis, resulting in substantial internal but minimal external perturbations. This analysis provides evidence for a potential role of AMT transporters in the regulatory/signalling network of nitrogen metabolism and the existence of a novel fourth regulatory mechanism controlling glutamine synthetase activity.
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Affiliation(s)
- Giorgio Perin
- Department of Life Sciences, Imperial College London, London, UK
| | - Tyler Fletcher
- Complex Carbohydrate Research Center and Department of Chemistry, University of Georgia, Athens, Georgia, USA
| | - Virag Sagi-Kiss
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - David C A Gaboriau
- Facility for Imaging by Light Microscopy, NHLI, Imperial College London, London, UK
| | - Mathew R Carey
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Jacob G Bundy
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Patrik R Jones
- Department of Life Sciences, Imperial College London, London, UK
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19
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Chen Z, Shang JL, Hou S, Li T, Li Q, Yang YW, Hess WR, Qiu BS. Genomic and transcriptomic insights into the habitat adaptation of the diazotrophic paddy-field cyanobacterium Nostoc sphaeroides. Environ Microbiol 2021; 23:5802-5822. [PMID: 33848055 DOI: 10.1111/1462-2920.15521] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 03/25/2021] [Accepted: 04/08/2021] [Indexed: 12/13/2022]
Abstract
Nitrogen-fixing cyanobacteria are common in paddy fields, one of the most productive wetland ecosystems. Here, we present the complete genome of Nostoc sphaeroides, a paddy-field diazotroph used for food and medicine for more than 1700 years and deciphered the transcriptional regulation during the developmental transition from hormogonia to vegetative filaments with heterocysts. The genome of N. sphaeroides consists of one circular chromosome (6.48 Mb), one of the largest ever reported megaplasmids (2.34 Mb), and seven plasmids. Multiple gene families involved in the adaption to high solar radiation and water fluctuation conditions were found expanded, while genes involved in anoxic adaptation and phosphonate utilization are located on the megaplasmid, suggesting its indispensable role in environmental adaptation. Distinct gene expression patterns were observed during the light-intensity-regulated transition from hormogonia to vegetative filaments, specifically, genes encoding proteins involved in photosynthetic light reaction, carbon fixation, nitrogen metabolism and heterocyst differentiation were significantly upregulated, whereas genes related to cell motility were down-regulated. Our results provide genomic and transcriptomic insights into the adaptation of a filamentous nitrogen-fixing cyanobacterium to the highly dynamic paddy-field habitat, suggesting N. sphaeroides as an excellent system to understand the transition from aquatic to terrestrial habitats and to support sustainable rice production.
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Affiliation(s)
- Zhen Chen
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China.,Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, 435002, China
| | - Jin-Long Shang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Shengwei Hou
- Department of Biological Sciences, University of Southern California, CA, Los Angeles, 90089, USA
| | - Tao Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Science, Wuhan, Hubei, 430072, China
| | - Qi Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Science, Wuhan, Hubei, 430072, China
| | - Yi-Wen Yang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Wolfgang R Hess
- Genetics and Experimental Bioinformatics, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, 79104, Germany
| | - 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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He H, Miao R, Huang L, Jiang H, Cheng Y. Vegetative cells may perform nitrogen fixation function under nitrogen deprivation in Anabaena sp. strain PCC 7120 based on genome-wide differential expression analysis. PLoS One 2021; 16:e0248155. [PMID: 33662009 PMCID: PMC7932525 DOI: 10.1371/journal.pone.0248155] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 02/20/2021] [Indexed: 11/25/2022] Open
Abstract
Nitrogen assimilation is strictly regulated in cyanobacteria. In an inorganic nitrogen-deficient environment, some vegetative cells of the cyanobacterium Anabaena differentiate into heterocysts. We assessed the photosynthesis and nitrogen-fixing capacities of heterocysts and vegetative cells, respectively, at the transcriptome level. RNA extracted from nitrogen-replete vegetative cells (NVs), nitrogen-deprived vegetative cells (NDVs), and nitrogen-deprived heterocysts (NDHs) in Anabaena sp. strain PCC 7120 was evaluated by transcriptome sequencing. Paired comparisons of NVs vs. NDHs, NVs vs. NDVs, and NDVs vs. NDHs revealed 2,044 differentially expressed genes (DEGs). Kyoto Encyclopedia of Genes and Genomes enrichment analysis of the DEGs showed that carbon fixation in photosynthetic organisms and several nitrogen metabolism-related pathways were significantly enriched. Synthesis of Gvp (Gas vesicle synthesis protein gene) in NVs was blocked by nitrogen deprivation, which may cause Anabaena cells to sink and promote nitrogen fixation under anaerobic conditions; in contrast, heterocysts may perform photosynthesis under nitrogen deprivation conditions, whereas the nitrogen fixation capability of vegetative cells was promoted by nitrogen deprivation. Immunofluorescence analysis of nitrogenase iron protein suggested that the nitrogen fixation capability of vegetative cells was promoted by nitrogen deprivation. Our findings provide insight into the molecular mechanisms underlying nitrogen fixation and photosynthesis in vegetative cells and heterocysts at the transcriptome level. This study provides a foundation for further functional verification of heterocyst growth, differentiation, and water bloom control.
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Affiliation(s)
- Hongli He
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
| | - Runyu Miao
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
| | - Lilong Huang
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
| | - Hongshan Jiang
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
| | - Yunqing Cheng
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
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21
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Ma J, Wang P. Effects of rising atmospheric CO 2 levels on physiological response of cyanobacteria and cyanobacterial bloom development: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 754:141889. [PMID: 32920383 DOI: 10.1016/j.scitotenv.2020.141889] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/15/2020] [Accepted: 08/20/2020] [Indexed: 05/19/2023]
Abstract
Increasing atmospheric CO2 concentration negatively impacts aquatic ecosystems and may exacerbate the problem of undesirable cyanobacterial bloom development in freshwater ecosystems. Elevated levels of atmospheric CO2 may increase the levels of dissolved CO2 in freshwater systems, via air-water exchanges, enhancing primary production in the water and catchments. Although high CO2 levels improve cyanobacterial growth and increase cyanobacterial biomass, the impacts on their internal physiological processes can be more complex. Here, we have reviewed previous studies to evaluate the physiological responses of cyanobacteria to high concentrations of CO2. In response to high CO2 concentrations, the pressures of inorganic carbon absorption are reduced, and carbon concentration mechanisms are downregulated, affecting the intracellular metabolic processes and competitiveness of the cyanobacteria. Nitrogen and phosphorus metabolism and light utilization are closely related to CO2 assimilation, and these processes are likely to be affected by resource and energy reallocation when CO2 levels are high. Additionally, the responses of diazotrophic and toxic cyanobacteria to elevated CO2 levels were specifically reviewed. The responses of diazotrophic cyanobacteria to elevated CO2 concentrations were found to be inconsistent, probably because of differences in other factors in experimental designs. Toxic cyanobacteria tended to be superior to non-toxic strains at low levels of CO2; however, the specific effects of microcystin on the regulation require further investigation. Furthermore, the effects of increasing CO2 levels on cyanobacterial competitiveness in phytoplankton communities and nutrient cycling in aquatic ecosystems were reviewed. High CO2 concentrations may make cyanobacteria less competitive relative to other algal taxa; however, due to the complexity of natural systems and the specificity of algal species, the dominant positions of the cyanobacteria do not seems to be changed. To better understand cyanobacterial responses to elevated CO2 levels and help control cyanobacterial bloom developments, this review has identified key areas for future research.
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Affiliation(s)
- Jingjie Ma
- Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, People's Republic of China; College of Environment, Hohai University, Nanjing 210098, People's Republic of China
| | - Peifang Wang
- Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, People's Republic of China; College of Environment, Hohai University, Nanjing 210098, People's Republic of China.
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22
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Álvarez-Escribano I, Brenes-Álvarez M, Olmedo-Verd E, Georg J, Hess WR, Vioque A, Muro-Pastor AM. NsiR3, a nitrogen stress-inducible small RNA, regulates proline oxidase expression in the cyanobacterium Nostoc sp. PCC 7120. FEBS J 2020; 288:1614-1629. [PMID: 32799414 DOI: 10.1111/febs.15516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/17/2020] [Accepted: 08/10/2020] [Indexed: 11/30/2022]
Abstract
NsiR3 (nitrogen stress-inducible RNA 3) is a small noncoding RNA strongly conserved in heterocyst-forming cyanobacteria. In Nostoc sp. PCC 7120, transcription of NsiR3 is induced by nitrogen starvation and depends on the global nitrogen regulator NtcA. A conserved NtcA-binding site is centered around position -42.5 with respect to the transcription start site of NsiR3 homologs, and NtcA binds in vitro to a DNA fragment containing this sequence. In the absence of combined nitrogen, NsiR3 expression is induced in all cells along the Nostoc filament but much more strongly in heterocysts, differentiated cells devoted to nitrogen fixation. Co-expression analysis of transcriptomic data obtained from microarrays hybridized with RNA obtained from Nostoc wild-type or mutant strains grown in the presence of ammonium or in the absence of combined nitrogen revealed that the expression profile of gene putA (proline oxidase) correlates negatively with that of NsiR3. Using a heterologous system in Escherichia coli, we show that NsiR3 binds to the 5'-UTR of putA mRNA, resulting in reduced expression of a reporter gene. Overexpression of NsiR3 in Nostoc resulted in strong reduction of putA mRNA accumulation, further supporting the negative regulation of putA by NsiR3. The higher expression of NsiR3 in heterocysts versus vegetative cells of the N2 -fixing filament could contribute to the previously described absence of putA mRNA and of the catabolic pathway to produce glutamate from arginine via proline specifically in heterocysts. Post-transcriptional regulation by NsiR3 represents an indirect NtcA-operated regulatory mechanism of putA expression. DATABASE: Microarray data are available in GEO database under accession numbers GSE120377 and GSE150191.
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Affiliation(s)
- Isidro Álvarez-Escribano
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, Spain
| | - Manuel Brenes-Álvarez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, Spain
| | - Elvira Olmedo-Verd
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, Spain
| | - Jens Georg
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Wolfgang R Hess
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Agustín Vioque
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, Spain
| | - Alicia M Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, Spain
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Brenes‐Álvarez M, Minguet M, Vioque A, Muro‐Pastor AM. NsiR1, a smallRNAwith multiple copies, modulates heterocyst differentiation in the cyanobacteriumNostocsp.PCC7120. Environ Microbiol 2020; 22:3325-3338. [DOI: 10.1111/1462-2920.15103] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/22/2020] [Accepted: 05/24/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Manuel Brenes‐Álvarez
- Instituto de Bioquímica Vegetal y Fotosíntesis Consejo Superior de Investigaciones Científicas and Universidad de Sevilla Sevilla Spain
| | - Marina Minguet
- Instituto de Bioquímica Vegetal y Fotosíntesis Consejo Superior de Investigaciones Científicas and Universidad de Sevilla Sevilla Spain
| | - Agustín Vioque
- Instituto de Bioquímica Vegetal y Fotosíntesis Consejo Superior de Investigaciones Científicas and Universidad de Sevilla Sevilla Spain
| | - Alicia M. Muro‐Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis Consejo Superior de Investigaciones Científicas and Universidad de Sevilla Sevilla Spain
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24
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Harish, Seth K. Molecular circuit of heterocyst differentiation in cyanobacteria. J Basic Microbiol 2020; 60:738-745. [DOI: 10.1002/jobm.202000266] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 05/10/2020] [Accepted: 05/28/2020] [Indexed: 02/01/2023]
Affiliation(s)
- Harish
- Plant Biotechnology Laboratory, Department of Botany; Mohanlal Sukhadia University; Udaipur Rajasthan India
| | - Kunal Seth
- Department of Botany; Government Science College; Pardi Valsad Gujarat India
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25
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Thiel T. Organization and regulation of cyanobacterial nif gene clusters: implications for nitrogenase expression in plant cells. FEMS Microbiol Lett 2020; 366:5470946. [PMID: 31062027 DOI: 10.1093/femsle/fnz077] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 04/11/2019] [Indexed: 12/16/2022] Open
Abstract
For over 50 years scientists have considered the possibility of engineering a plant with nitrogen fixation capability, freeing farmers from their dependence on nitrogen fertilizers. With the development of the tools of synthetic biology, more progress has been made toward this goal in the last 5 years than in the previous five decades. Most of the effort has focused on nitrogenase genes from Klebsiella oxytoca, which has complex gene regulation. There may be advantages in using nitrogenase genes from cyanobacteria, which comprise large polycistronic gene clusters that may be easier to manipulate and eventually express in a plant. The fact that some diatoms have a cyanobacterial nitrogen fixing organelle further supports the idea that a cyanobacterial nitrogenase gene cluster may function in a newly-engineered, cyanobacterial-based plant organelle, a nitroplast. This review describes recent attempts to express the nif genes from Anabaena variabilis ATCC 29413, Leptolyngbya boryana dg5 and Cyanothece sp. ATCC 51142 in heterologous cyanobacteria in the context of the organization of the nitrogenase genes and their regulation by the transcription factor CnfR via its highly conserved binding sites.
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Affiliation(s)
- Teresa Thiel
- Department of Biology, University of Missouri-St. Louis, One University Blvd., St. Louis, MO 63121, USA
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26
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Álvarez-Escribano I, Brenes-Álvarez M, Olmedo-Verd E, Vioque A, Muro-Pastor AM. The Nitrogen Stress-Repressed sRNA NsrR1 Regulates Expression of all1871, a Gene Required for Diazotrophic Growth in Nostoc sp. PCC 7120. Life (Basel) 2020; 10:life10050054. [PMID: 32365616 PMCID: PMC7281752 DOI: 10.3390/life10050054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/26/2020] [Accepted: 04/27/2020] [Indexed: 12/14/2022] Open
Abstract
Small regulatory RNAs (sRNAs) are post-transcriptional regulators of bacterial gene expression. In cyanobacteria, the responses to nitrogen availability, that are mostly controlled at the transcriptional level by NtcA, involve also at least two small RNAs, namely NsiR4 (nitrogen stress-induced RNA 4) and NsrR1 (nitrogen stress-repressed RNA 1). Prediction of possible mRNA targets regulated by NsrR1 in Nostoc sp. PCC 7120 allowed, in addition to previously described nblA, the identification of all1871, a nitrogen-regulated gene encoding a protein of unknown function that we describe here as required for growth at the expense of atmospheric nitrogen (N2). We show that transcription of all1871 is induced upon nitrogen step-down independently of NtcA. All1871 accumulation is repressed by NsrR1 and its expression is stronger in heterocysts, specialized cells devoted to N2 fixation. We demonstrate specific interaction between NsrR1 and the 5′ untranslated region (UTR) of the all1871 mRNA, that leads to decreased expression of all1871. Because transcription of NsrR1 is partially repressed by NtcA, post-transcriptional regulation by NsrR1 would constitute an indirect way of NtcA-mediated regulation of all1871.
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The Integrity of the Cell Wall and Its Remodeling during Heterocyst Differentiation Are Regulated by Phylogenetically Conserved Small RNA Yfr1 in Nostoc sp. Strain PCC 7120. mBio 2020; 11:mBio.02599-19. [PMID: 31964726 PMCID: PMC6974561 DOI: 10.1128/mbio.02599-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Bacterial small RNAs (sRNAs) are important players affecting the regulation of essentially every aspect of bacterial physiology. The cell wall is a highly dynamic structure that protects bacteria from their fluctuating environment. Cell envelope remodeling is particularly critical for bacteria that undergo differentiation processes, such as spore formation or differentiation of heterocysts. Heterocyst development involves the deposition of additional layers of glycolipids and polysaccharides outside the outer membrane. Here, we show that a cyanobacterial phylogenetically conserved small regulatory RNA, Yfr1, coordinates the expression of proteins involved in cell wall-related processes, including peptidoglycan metabolism and transport of different molecules, as well as expression of several proteins involved in heterocyst differentiation. Yfr1 is a strictly conserved small RNA in cyanobacteria. A bioinformatic prediction to identify possible interactions of Yfr1 with mRNAs was carried out by using the sequences of Yfr1 from several heterocyst-forming strains, including Nostoc sp. strain PCC 7120. The results of the prediction were enriched in genes encoding outer membrane proteins and enzymes related to peptidoglycan biosynthesis and turnover. Heterologous expression assays with Escherichia coli demonstrated direct interactions of Yfr1 with mRNAs of 11 of the candidate genes. The expression of 10 of them (alr2458, alr4550, murC, all4829, all2158, mraY, alr2269, alr0834, conR, patN) was repressed by interaction with Yfr1, whereas the expression of amiC2, encoding an amidase, was increased. The interactions between Yfr1 and the 11 mRNAs were confirmed by site-directed mutagenesis of Yfr1. Furthermore, a Nostoc strain with reduced levels of Yfr1 had larger amounts of mraY and murC mRNAs, supporting a role for Yfr1 in the regulation of those genes. Nostoc strains with either reduced or increased expression of Yfr1 showed anomalies in cell wall completion and were more sensitive to vancomycin than the wild-type strain. Furthermore, growth in the absence of combined nitrogen, which involves the differentiation of heterocysts, was compromised in the strain overexpressing Yfr1, and filaments were broken at the connections between vegetative cells and heterocysts. These results indicate that Yfr1 is an important regulator of cell wall homeostasis and correct cell wall remodeling during heterocyst differentiation.
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28
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Fang X, Kalathil S, Reisner E. Semi-biological approaches to solar-to-chemical conversion. Chem Soc Rev 2020; 49:4926-4952. [DOI: 10.1039/c9cs00496c] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This review provides an overview of the cross-disciplinary field of semi-artificial photosynthesis, which combines strengths of biocatalysis and artificial photosynthesis to develop new concepts and approaches for solar-to-chemical conversion.
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Affiliation(s)
- Xin Fang
- Department of Chemistry
- University of Cambridge
- Cambridge CB2 1EW
- UK
| | - Shafeer Kalathil
- Department of Chemistry
- University of Cambridge
- Cambridge CB2 1EW
- UK
| | - Erwin Reisner
- Department of Chemistry
- University of Cambridge
- Cambridge CB2 1EW
- UK
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29
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Allen JF, Thake B, Martin WF. Nitrogenase Inhibition Limited Oxygenation of Earth's Proterozoic Atmosphere. TRENDS IN PLANT SCIENCE 2019; 24:1022-1031. [PMID: 31447302 DOI: 10.1016/j.tplants.2019.07.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/10/2019] [Accepted: 07/10/2019] [Indexed: 05/24/2023]
Abstract
Cyanobacteria produced the oxygen that began to accumulate on Earth 2.5 billion years ago, at the dawn of the Proterozoic Eon. By 2.4 billion years ago, the Great Oxidation Event (GOE) marked the onset of an atmosphere containing oxygen. The oxygen content of the atmosphere then remained low for almost 2 billion years. Why? Nitrogenase, the sole nitrogen-fixing enzyme on Earth, controls the entry of molecular nitrogen into the biosphere. Nitrogenase is inhibited in air containing more than 2% oxygen: the concentration of oxygen in the Proterozoic atmosphere. We propose that oxygen inhibition of nitrogenase limited Proterozoic global primary production. Oxygen levels increased when upright terrestrial plants isolated nitrogen fixation in soil from photosynthetic oxygen production in shoots and leaves.
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Affiliation(s)
- John F Allen
- Research Department of Genetics, Evolution and Environment, Darwin Building, University College London, Gower Street, London WC1E 6BT, UK.
| | - Brenda Thake
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - William F Martin
- Institute of Molecular Evolution, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstr. 1, 40225 Duesseldorf, Germany
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patD, a Gene Regulated by NtcA, Is Involved in the Optimization of Heterocyst Frequency in the Cyanobacterium Anabaena sp. Strain PCC 7120. J Bacteriol 2019; 201:JB.00457-19. [PMID: 31405917 DOI: 10.1128/jb.00457-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 08/04/2019] [Indexed: 11/20/2022] Open
Abstract
In the filamentous multicellular cyanobacterium Anabaena sp. strain PCC 7120, 5 to 10% of the cells differentiate into heterocysts, which are specialized in N2 fixation. Heterocysts and vegetative cells are mutually dependent for filament growth through nutrient exchange. Thus, the heterocyst frequency should be optimized to maintain the cellular carbon and nitrogen (C/N) balance for filament fitness in the environment. Here, we report the identification of patD, whose expression is directly activated in developing cells by the transcription factor NtcA. The inactivation of patD increases heterocyst frequency and promotes the upregulation of the positive regulator of heterocyst development hetR, whereas its overexpression decreases the heterocyst frequency. The change in heterocyst frequency resulting from the inactivation of patD leads to the reduction in competitiveness of the filaments under combined-nitrogen-depleted conditions. These results indicate that patD regulates heterocyst frequency in Anabaena sp. PCC 7120, ensuring its optimal filament growth.IMPORTANCE Microorganisms have evolved various strategies in order to adapt to the environment and compete with other organisms. Heterocyst differentiation is a prokaryotic model for studying complex cellular regulation. The NtcA-regulated gene patD controls the ratio of heterocysts relative to vegetative cells on the filaments of Anabaena sp. strain PCC 7120. Such a regulation provides a mechanism through which carbon fixation by vegetative cells and nitrogen fixation by heterocysts are properly balanced to ensure optimal growth and keep a competitive edge for long-term survival.
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31
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Li X, Mustila H, Magnuson A, Stensjö K. Homologous overexpression of NpDps2 and NpDps5 increases the tolerance for oxidative stress in the multicellular cyanobacterium Nostoc punctiforme. FEMS Microbiol Lett 2019; 365:5071947. [PMID: 30107525 PMCID: PMC6116882 DOI: 10.1093/femsle/fny198] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 08/10/2018] [Indexed: 12/30/2022] Open
Abstract
The filamentous cyanobacterium Nostoc punctiforme has several oxidative stress-managing systems, including Dps proteins. Dps proteins belong to the ferritin superfamily and are involved in abiotic stress management in prokaryotes. Previously, we found that one of the five Dps proteins in N. punctiforme, NpDps2, was critical for H2O2 tolerance. Stress induced by high light intensities is aggravated in N. punctiforme strains deficient of either NpDps2, or the bacterioferritin-like NpDps5. Here, we have investigated the capacity of NpDps2 and NpDps5 to enhance stress tolerance by homologous overexpression of these two proteins in N. punctiforme. Both overexpression strains were found to tolerate twice as high concentrations of added H2O2 as the control strain, indicating that overexpression of either NpDps2 or NpDps5 will enhance the capacity for H2O2 tolerance. Under high light intensities, the overexpression of the two NpDps did not enhance the tolerance against general light-induced stress. However, overexpression of the heterocyst-specific NpDps5 in all cells of the filament led to a higher amount of chlorophyll-binding proteins per cell during diazotrophic growth. The OENpDps5 strain also showed an increased tolerance to ammonium-induced oxidative stress. Our results provide information of how Dps proteins may be utilised for engineering of cyanobacteria with enhanced stress tolerance.
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Affiliation(s)
- Xin Li
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE 75120 Uppsala, Swedens
| | - Henna Mustila
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE 75120 Uppsala, Swedens
| | - Ann Magnuson
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE 75120 Uppsala, Swedens
| | - Karin Stensjö
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE 75120 Uppsala, Swedens
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32
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Wells KN, Videau P, Nelson D, Eiting JE, Philmus B. The influence of sigma factors and ribosomal recognition elements on heterologous expression of cyanobacterial gene clusters in Escherichia coli. FEMS Microbiol Lett 2019; 365:5047307. [PMID: 29982530 DOI: 10.1093/femsle/fny164] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/28/2018] [Indexed: 12/16/2022] Open
Abstract
Cyanobacterial natural products offer new possibilities for drugs and lead compounds but many factors can inhibit the production of sufficient yields for pharmaceutical processes. While Escherichia coli and Streptomyces sp. have been used as heterologous expression hosts to produce cyanobacterial natural products, they have not met with resounding success largely due to their inability to recognize cyanobacterial promoter regions. Recent work has shown that the filamentous freshwater cyanobacterium Anabaena sp. strain PCC 7120 recognizes various cyanobacterial promoter regions and can produce lyngbyatoxin A from the native promoter. Introduction of Anabaena sigma factors into E. coli might allow the native transcriptional machinery to recognize cyanobacterial promoters. Here, all 12 Anabaena sigma factors were expressed in E. coli and subsets were found to initiate transcription from several cyanobacterial promoters based on transcriptional fusions to the chloramphenicol acetyltransferase (CAT) reporter. Expression of individual Anabaena sigma factors in E. coli did not result in lyngbyatoxin A production from its native cyanobacterial gene cluster, possibly hindered by deficiencies in recognition of cyanobacterial ribosomal binding sites by native E. coli translational machinery. This represents an important step toward engineering E. coli into a general heterologous expression host for cyanobacterial biosynthetic gene cluster expression.
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Affiliation(s)
- Kaitlyn N Wells
- Undergraduate Honors College, 450 Learning Innovation Center, Oregon State University, Corvallis, OR 97331, USA
| | - Patrick Videau
- Department of Pharmaceutical Sciences, College of Pharmacy, 203 Pharmacy Bldg., Oregon State University, Corvallis, OR 97331, USA
| | - Dylan Nelson
- Department of Pharmaceutical Sciences, College of Pharmacy, 203 Pharmacy Bldg., Oregon State University, Corvallis, OR 97331, USA
| | - Jessie E Eiting
- Department of Pharmaceutical Sciences, College of Pharmacy, 203 Pharmacy Bldg., Oregon State University, Corvallis, OR 97331, USA
| | - Benjamin Philmus
- Department of Pharmaceutical Sciences, College of Pharmacy, 203 Pharmacy Bldg., Oregon State University, Corvallis, OR 97331, USA
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Structural diffusion properties of two atypical Dps from the cyanobacterium Nostoc punctiforme disclose interactions with ferredoxins and DNA. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:148063. [PMID: 31419396 DOI: 10.1016/j.bbabio.2019.148063] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 08/06/2019] [Accepted: 08/10/2019] [Indexed: 12/14/2022]
Abstract
Ferritin-like proteins, Dps (DNA-binding protein from starved cells), store iron and play a key role in the iron homeostasis in bacteria, yet their iron releasing machinery remains largely unexplored. The electron donor proteins that may interact with Dps and promote the mobilization of the stored iron have hitherto not been identified. Here, we investigate the binding capacity of the two atypical Dps proteins NpDps4 and NpDps5 from Nostoc punctiforme to isolated ferredoxins. We report NpDps-ferredoxin interactions by fluorescence correlation spectroscopy (FCS) and fluorescence resonance energy transfer (FRET) methods. Dynamic light scattering, size exclusion chromatography and native gel electrophoresis results show that NpDps4 forms a dodecamer at both pH 6.0 and pH 8.0, while NpDps5 forms a dodecamer only at pH 6.0. In addition, FCS data clearly reveal that the non-canonical NpDps5 interacts with DNA at pH 6.0. Our spectroscopic analysis shows that [FeS] centers of the three recombinantly expressed and isolated ferredoxins are properly incorporated and are consistent with their respective native states. The results support our hypothesis that ferredoxins could be involved in cellular iron homeostasis by interacting with Dps and assisting the release of stored iron.
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Olmedo-Verd E, Brenes-Álvarez M, Vioque A, Muro-Pastor AM. A Heterocyst-Specific Antisense RNA Contributes to Metabolic Reprogramming in Nostoc sp. PCC 7120. PLANT & CELL PHYSIOLOGY 2019; 60:1646-1655. [PMID: 31093664 DOI: 10.1093/pcp/pcz087] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 04/28/2019] [Indexed: 06/09/2023]
Abstract
Upon nitrogen deficiency, some filamentous cyanobacteria differentiate specialized cells, called heterocysts, devoted to N2 fixation. Heterocysts appear regularly spaced along the filaments and exhibit structural and metabolic adaptations, such as loss of photosynthetic CO2 fixation or increased respiration, to provide a proper microaerobic environment for its specialized function. Heterocyst development is under transcriptional control of the global nitrogen regulator NtcA and the specific regulator HetR. Transcription of a large number of genes is induced or repressed upon nitrogen deficiency specifically in cells undergoing differentiation. In recent years, the HetR regulon has been described to include heterocyst-specific trans-acting small RNAs and antisense RNAs (asRNAs), suggesting that there is an additional layer of post-transcriptional regulation involved in heterocyst development. Here, we characterize in the cyanobacterium Nostoc (Anabaena) sp. PCC 7120 an asRNA, that we call as_glpX, transcribed within the glpX gene encoding the Calvin cycle bifunctional enzyme sedoheptulose-1,7-bisphosphatase/fructose-1,6-bisphosphatase (SBPase). Transcription of as_glpX is restricted to heterocysts and is induced very early during the process of differentiation. Expression of as_glpX RNA promotes the cleavage of the glpX mRNA by RNase III, resulting in a reduced amount of SBPase. Therefore, the early expression of this asRNA could contribute to the quick shut-down of CO2 fixation in those cells in the filament that are undergoing differentiation into heterocysts. In summary, as_glpX is the first naturally occurring asRNA shown to rapidly and dynamically regulate metabolic transformation in Nostoc heterocysts. The use of antisense transcripts to manipulate gene expression specifically in heterocysts could became a useful tool for metabolic engineering in cyanobacteria.
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Affiliation(s)
- Elvira Olmedo-Verd
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
| | - Manuel Brenes-Álvarez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
| | - Agustín Vioque
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
| | - Alicia M Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
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35
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Roles of DevBCA-like ABC transporters in the physiology of Anabaena sp. PCC 7120. Int J Med Microbiol 2019; 309:325-330. [DOI: 10.1016/j.ijmm.2019.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 04/10/2019] [Accepted: 04/26/2019] [Indexed: 01/19/2023] Open
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Shvarev D, Nishi CN, Maldener I. Two DevBCA‐like ABC transporters are involved in the multidrug resistance of the cyanobacterium
Anabaena
sp. PCC 7120. FEBS Lett 2019; 593:1818-1826. [DOI: 10.1002/1873-3468.13450] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 05/07/2019] [Accepted: 05/14/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Dmitry Shvarev
- Organismic Interactions Interfaculty Institute of Microbiology and Infection Medicine Eberhard Karls University of Tübingen Germany
| | - Carolina N. Nishi
- Organismic Interactions Interfaculty Institute of Microbiology and Infection Medicine Eberhard Karls University of Tübingen Germany
| | - Iris Maldener
- Organismic Interactions Interfaculty Institute of Microbiology and Infection Medicine Eberhard Karls University of Tübingen Germany
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37
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Brenes‐Álvarez M, Mitschke J, Olmedo‐Verd E, Georg J, Hess WR, Vioque A, Muro‐Pastor AM. Elements of the heterocyst‐specific transcriptome unravelled by co‐expression analysis inNostocsp. PCC 7120. Environ Microbiol 2019; 21:2544-2558. [DOI: 10.1111/1462-2920.14647] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/06/2019] [Accepted: 05/01/2019] [Indexed: 12/20/2022]
Affiliation(s)
- Manuel Brenes‐Álvarez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla E‐41092 Sevilla Spain
| | - Jan Mitschke
- Genetics and Experimental Bioinformatics, Faculty of BiologyUniversity of Freiburg D‐79104 Freiburg Germany
| | - Elvira Olmedo‐Verd
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla E‐41092 Sevilla Spain
| | - Jens Georg
- Genetics and Experimental Bioinformatics, Faculty of BiologyUniversity of Freiburg D‐79104 Freiburg Germany
| | - Wolfgang R. Hess
- Genetics and Experimental Bioinformatics, Faculty of BiologyUniversity of Freiburg D‐79104 Freiburg Germany
- Freiburg Institute for Advanced Studies, University of Freiburg D‐79104 Freiburg Germany
| | - Agustín Vioque
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla E‐41092 Sevilla Spain
| | - Alicia M. Muro‐Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla E‐41092 Sevilla Spain
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38
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Shvarev D, Nishi CN, Maldener I. Glycolipid composition of the heterocyst envelope of Anabaena sp. PCC 7120 is crucial for diazotrophic growth and relies on the UDP-galactose 4-epimerase HgdA. Microbiologyopen 2019; 8:e00811. [PMID: 30803160 PMCID: PMC6692557 DOI: 10.1002/mbo3.811] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/10/2019] [Accepted: 01/14/2019] [Indexed: 01/05/2023] Open
Abstract
The nitrogenase complex in the heterocysts of the filamentous freshwater cyanobacterium Anabaenasp. PCC 7120 fixes atmospheric nitrogen to allow diazotrophic growth. The heterocyst cell envelope protects the nitrogenase from oxygen and consists of a polysaccharide and a glycolipid layer that are formed by a complex process involving the recruitment of different proteins. Here, we studied the function of the putative nucleoside‐diphosphate‐sugar epimerase HgdA, which along with HgdB and HgdC is essential for deposition of the glycolipid layer and growth without a combined nitrogen source. Using site‐directed mutagenesis and single homologous recombination approach, we performed a thoroughly functional characterization of HgdA and confirmed that the glycolipid layer of the hgdAmutant heterocyst is aberrant as shown by transmission electron microscopy and chemical analysis. The hgdA gene was expressed during late stages of the heterocyst differentiation. GFP‐tagged HgdA protein localized inside the heterocysts. The purified HgdA protein had UDP‐galactose 4‐epimerase activity in vitro. This enzyme could be responsible for synthesis of heterocyst‐specific glycolipid precursors, which could be transported over the cell wall by the ABC transporter components HgdB/HgdC.
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Affiliation(s)
- Dmitry Shvarev
- Organismic Interactions, Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Carolina N Nishi
- Organismic Interactions, Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Iris Maldener
- Organismic Interactions, Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
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Abstract
Global (metabolic) regulatory networks allow microorganisms to survive periods of nitrogen starvation or general nutrient stress. Uptake and utilization of various nitrogen sources are thus commonly tightly regulated in Prokarya (Bacteria and Archaea) in response to available nitrogen sources. Those well-studied regulations occur mainly at the transcriptional and posttranslational level. Surprisingly, and in contrast to their involvement in most other stress responses, small RNAs (sRNAs) involved in the response to environmental nitrogen fluctuations are only rarely reported. In addition to sRNAs indirectly affecting nitrogen metabolism, only recently it was demonstrated that three sRNAs were directly involved in regulation of nitrogen metabolism in response to changes in available nitrogen sources. All three trans-acting sRNAs are under direct transcriptional control of global nitrogen regulators and affect expression of components of nitrogen metabolism (glutamine synthetase, nitrogenase, and PII-like proteins) by either masking the ribosome binding site and thus inhibiting translation initiation or stabilizing the respective target mRNAs. Most likely, there are many more sRNAs and other types of noncoding RNAs, e.g., riboswitches, involved in the regulation of nitrogen metabolism in Prokarya that remain to be uncovered. The present review summarizes the current knowledge on sRNAs involved in nitrogen metabolism and their biological functions and targets.
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Volgusheva A, Kosourov S, Lynch F, Allahverdiyeva Y. Immobilized heterocysts as microbial factories for sustainable nitrogen fixation. J Biotechnol 2019; 306S:100016. [DOI: 10.1016/j.btecx.2020.100016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 02/14/2020] [Accepted: 02/21/2020] [Indexed: 12/22/2022]
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Popova AA, Semashko TA, Kostina NV, Rasmussen U, Govorun VM, Koksharova OA. The Cyanotoxin BMAA Induces Heterocyst Specific Gene Expression in Anabaena sp. PCC 7120 under Repressive Conditions. Toxins (Basel) 2018; 10:toxins10110478. [PMID: 30453523 PMCID: PMC6266585 DOI: 10.3390/toxins10110478] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 11/10/2018] [Accepted: 11/12/2018] [Indexed: 12/12/2022] Open
Abstract
Cyanobacteria synthesize neurotoxic β-N-methylamino-l-alanine (BMAA). The roles of this non-protein amino acid in cyanobacterial cells are insufficiently studied. During diazotrophic growth, filamentous cyanobacteria form single differentiated cells, called heterocysts, which are separated by approximately 12–15 vegetative cells. When combined nitrogen is available, heterocyst formation is blocked and cyanobacterial filaments contain only vegetative cells. In the present study, we discovered that exogenous BMAA induces the process of heterocyst formation in filamentous cyanobacteria under nitrogen-replete conditions that normally repress cell differentiation. BMAA treated cyanobacteria form heterocyst-like dark non-fluorescent non-functional cells. It was found that glutamate eliminates the BMAA mediated derepression. Quantitative polymerase chain reaction (qPCR) permitted to detect the BMAA impact on the transcriptional activity of several genes that are implicated in nitrogen assimilation and heterocyst formation in Anabaena sp. PCC 7120. We demonstrated that the expression of several essential genes increases in the BMAA presence under repressive conditions.
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Affiliation(s)
- Alexandra A Popova
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square, 2, 123182 Moscow, Russia.
- Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Prospekt 60 let Oktyabrya, 7/2, 117312 Moscow, Russia.
| | - Tatiana A Semashko
- Scientific-Research Institute of Physical-Chemical Medicine, 119435 Moscow, Russia.
| | - Natalia V Kostina
- Soil Science Faculty, Lomonosov Moscow State University, Leninskie Gory, 1-12, 119991 Moscow, Russia.
| | - Ulla Rasmussen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden.
| | - Vadim M Govorun
- Scientific-Research Institute of Physical-Chemical Medicine, 119435 Moscow, Russia.
| | - Olga A Koksharova
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square, 2, 123182 Moscow, Russia.
- Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 1, 40, 119992 Moscow, Russia.
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Videau P, Cozy LM. Anabaena
sp. strain PCC 7120: Laboratory Maintenance, Cultivation, and Heterocyst Induction. ACTA ACUST UNITED AC 2018; 52:e71. [DOI: 10.1002/cpmc.71] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Patrick Videau
- Department of Biology, Southern Oregon University; Ashland Oregon
| | - Loralyn M. Cozy
- Department of Biology, Illinois Wesleyan University; Bloomington Illinois
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Wegelius A, Li X, Turco F, Stensjö K. Design and characterization of a synthetic minimal promoter for heterocyst-specific expression in filamentous cyanobacteria. PLoS One 2018; 13:e0203898. [PMID: 30204806 PMCID: PMC6133370 DOI: 10.1371/journal.pone.0203898] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/29/2018] [Indexed: 11/25/2022] Open
Abstract
Short and well defined promoters are essential for advancing cyanobacterial biotechnology. The heterocyst of Nostoc sp. is suggested as a microbial cell factory for oxygen sensitive catalysts, such as hydrogenases for hydrogen production, due to its microoxic environment. We identified and predicted promoter elements of possible significance through a consensus strategy using a pool of heterocyst-induced DIF+ promoters known from Anabaena sp. PCC 7120. To test if these conserved promoter elements were crucial for heterocyst-specific expression, promoter-yfp reporter constructs were designed. The characterization was accomplished by replacing, -35 and -10 regions and the upstream element, with well described elements from the trc promoter of Escherichia coli, which is also functional in Nostoc sp. From the in vivo spatial fluorescence of the different promoter-yfp reporters in Nostoc punctiforme ATCC 29133, we concluded that both the consensus -35 and extended -10 regions were important for heterocyst-specific expression. Further that the promoter strength could be improved by the addition of an upstream element. We designed a short synthetic promoter of 48 nucleotides, PsynDIF, including a consensus DIF1 sequence, a 17 base pair stretch of random nucleotides and an extended consensus -10 region, and thus generated the shortest promoter for heterocyst-specific expression to date.
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Affiliation(s)
- Adam Wegelius
- Department of Chemistry– Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Xin Li
- Department of Chemistry– Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Federico Turco
- Department of Chemistry– Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Karin Stensjö
- Department of Chemistry– Ångström Laboratory, Uppsala University, Uppsala, Sweden
- * E-mail:
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Rivers OS, Beurmann S, Dow A, Cozy LM, Videau P. Phenotypic Assessment Suggests Multiple Start Codons for HetN, an Inhibitor of Heterocyst Differentiation, in Anabaena sp. Strain PCC 7120. J Bacteriol 2018; 200:e00220-18. [PMID: 29784882 PMCID: PMC6060353 DOI: 10.1128/jb.00220-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 05/14/2018] [Indexed: 11/20/2022] Open
Abstract
Multicellular organisms must carefully regulate the timing, number, and location of specialized cellular development. In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, nitrogen-fixing heterocysts are interspersed between vegetative cells in a periodic pattern to achieve an optimal exchange of bioavailable nitrogen and reduced carbon. The spacing between heterocysts is regulated by the activity of two developmental inhibitors, PatS and HetN. PatS functions to create a de novo pattern from a homogenous field of undifferentiated cells, while HetN maintains the pattern throughout subsequent growth. Both PatS and HetN harbor the peptide motif ERGSGR, which is sufficient to inhibit development. While the small size of PatS makes the interpretation of inhibitory domains relatively simple, HetN is a 287-amino-acid protein with multiple functional regions. Previous work suggested the possibility of a truncated form of HetN containing the ERGSGR motif as the source of the HetN-derived inhibitory signal. In this work, we present evidence that the glutamate of the ERGSGR motif is required for proper HetN inhibition of heterocysts. Mutational analysis and subcellular localization indicate that the gene encoding HetN uses two methionine start codons (M1 and M119) to encode two protein forms: M1 is required for protein localization, while M119 is primarily responsible for inhibitory function. Finally, we demonstrate that patS and hetN are not functionally equivalent when expressed from the other gene's regulatory sequences. Taken together, these results help clarify the functional forms of HetN and will help refine future work defining a HetN-derived inhibitory signal in this model of one-dimensional periodic patterning.IMPORTANCE The proper placement of different cell types during a developmental program requires the creation and maintenance of a biological pattern to define the cells that will differentiate. Here we show that the HetN inhibitor, responsible for pattern maintenance of specialized nitrogen-fixing heterocyst cells in the filamentous cyanobacterium Anabaena, may be produced from two different start methionine codons. This work demonstrates that the two start sites are individually involved in a different HetN function, either membrane localization or inhibition of cellular differentiation.
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Affiliation(s)
- Orion S Rivers
- University of Hawaii at Manoa, Department of Microbiology, Honolulu, Hawaii, USA
| | - Silvia Beurmann
- University of Maryland, Institute for Genome Sciences, Maryland School of Medicine, Baltimore, Maryland, USA
| | - Allexa Dow
- University of Hawaii at Manoa, Department of Microbiology, Honolulu, Hawaii, USA
| | - Loralyn M Cozy
- Illinois Wesleyan University, Department of Biology, Bloomington, Illinois, USA
| | - Patrick Videau
- Dakota State University, Biology Department, College of Arts and Sciences, Madison, South Dakota
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The ABC Transporter Components HgdB and HgdC are Important for Glycolipid Layer Composition and Function of Heterocysts in Anabaena sp. PCC 7120. Life (Basel) 2018; 8:life8030026. [PMID: 30004454 PMCID: PMC6161253 DOI: 10.3390/life8030026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 06/21/2018] [Accepted: 06/28/2018] [Indexed: 12/13/2022] Open
Abstract
Anabaena sp. PCC 7120 is a filamentous cyanobacterium able to fix atmospheric nitrogen in semi-regularly spaced heterocysts. For correct heterocyst function, a special cell envelope consisting of a glycolipid layer and a polysaccharide layer is essential. We investigated the role of the genes hgdB and hgdC, encoding domains of a putative ABC transporter, in heterocyst maturation. We investigated the subcellular localization of the fusion protein HgdC-GFP and followed the differential expression of the hgdB and hgdC genes during heterocyst maturation. Using a single recombination approach, we created a mutant in hgdB gene and studied its phenotype by microscopy and analytical chromatography. Although heterocysts are formed in the mutant, the structure of the glycolipid layer is aberrant and also contains an atypical ratio of the two major glycolipids. As shown by a pull-down assay, HgdB interacts with the outer membrane protein TolC, which indicates a function as a type 1 secretion system. We show that the hgdB-hgdC genes are essential for the creation of micro-oxic conditions by influencing the correct composition of the glycolipid layer for heterocyst function. Our observations confirm the significance of the hgdB-hgdC gene cluster and shed light on a novel mode of regulation of heterocyst envelope formation.
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Driscoll CB, Meyer KA, Šulčius S, Brown NM, Dick GJ, Cao H, Gasiūnas G, Timinskas A, Yin Y, Landry ZC, Otten TG, Davis TW, Watson SB, Dreher TW. A closely-related clade of globally distributed bloom-forming cyanobacteria within the Nostocales. HARMFUL ALGAE 2018; 77:93-107. [PMID: 30005805 DOI: 10.1016/j.hal.2018.05.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/18/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
In order to better understand the relationships among current Nostocales cyanobacterial blooms, eight genomes were sequenced from cultured isolates or from environmental metagenomes of recent planktonic Nostocales blooms. Phylogenomic analysis of publicly available sequences placed the new genomes among a group of 15 genomes from four continents in a distinct ADA clade (Anabaena/Dolichospermum/Aphanizomenon) within the Nostocales. This clade contains four species-level groups, two of which include members with both Anabaena-like and Aphanizomenon flos-aquae-like morphology. The genomes contain many repetitive genetic elements and a sizable pangenome, in which ABC-type transporters are highly represented. Alongside common core genes for photosynthesis, the differentiation of N2-fixing heterocysts, and the uptake and incorporation of the major nutrients P, N and S, we identified several gene pathways in the pangenome that may contribute to niche partitioning. Genes for problematic secondary metabolites-cyanotoxins and taste-and-odor compounds-were sporadically present, as were other polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) gene clusters. By contrast, genes predicted to encode the ribosomally generated bacteriocin peptides were found in all genomes.
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Affiliation(s)
- Connor B Driscoll
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, OR, 97331, USA
| | - Kevin A Meyer
- Department of Earth & Environmental Sciences, University of Michigan, Ann Arbor, MI 48109-1005, USA; Cooperative Institute for Great Lakes Research (CIGLR), University of Michigan, Ann Arbor, MI 48109-1005, USA
| | - Sigitas Šulčius
- Laboratory of Algology and Microbial Ecology, Akademijos Str. 2, LT-08412, Vilnius, Lithuania
| | - Nathan M Brown
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, OR, 97331, USA
| | - Gregory J Dick
- Department of Earth & Environmental Sciences, University of Michigan, Ann Arbor, MI 48109-1005, USA
| | - Huansheng Cao
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, 427 E Tyler Mall, Tempe, AZ 85287, USA
| | - Giedrius Gasiūnas
- Department of Protein-DNA Interactions, Institute of Biotechnology, Vilnius University, Saulėtekio av. 7, LT-10257, Vilnius, Lithuania
| | - Albertas Timinskas
- Department of Bioinformatics, Institute of Biotechnology, Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania
| | - Yanbin Yin
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL, USA
| | - Zachary C Landry
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, OR, 97331, USA
| | - Timothy G Otten
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, OR, 97331, USA
| | - Timothy W Davis
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43402, USA
| | - Susan B Watson
- Environment and Climate Change Canada, Canada Centre for Inland Waters, Burlington, ON L7S 1A1, Canada
| | - Theo W Dreher
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, OR, 97331, USA; Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331, USA.
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48
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Three Substrains of the Cyanobacterium Anabaena sp. Strain PCC 7120 Display Divergence in Genomic Sequences and hetC Function. J Bacteriol 2018; 200:JB.00076-18. [PMID: 29686139 DOI: 10.1128/jb.00076-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/19/2018] [Indexed: 11/20/2022] Open
Abstract
Anabaena sp. strain PCC 7120 is a model strain for molecular studies of cell differentiation and patterning in heterocyst-forming cyanobacteria. Subtle differences in heterocyst development have been noticed in different laboratories working on the same organism. In this study, 360 mutations, including single nucleotide polymorphisms (SNPs), small insertion/deletions (indels; 1 to 3 bp), fragment deletions, and transpositions, were identified in the genomes of three substrains. Heterogeneous/heterozygous bases were also identified due to the polyploidy nature of the genome and the multicellular morphology but could be completely segregated when plated after filament fragmentation by sonication. hetC is a gene upregulated in developing cells during heterocyst formation in Anabaena sp. strain PCC 7120 and found in approximately half of other heterocyst-forming cyanobacteria. Inactivation of hetC in 3 substrains of Anabaena sp. PCC 7120 led to different phenotypes: the formation of heterocysts, differentiating cells that keep dividing, or the presence of both heterocysts and dividing differentiating cells. The expression of P hetZ -gfp in these hetC mutants also showed different patterns of green fluorescent protein (GFP) fluorescence. Thus, the function of hetC is influenced by the genomic background and epistasis and constitutes an example of evolution under way.IMPORTANCE Our knowledge about the molecular genetics of heterocyst formation, an important cell differentiation process for global N2 fixation, is mostly based on studies with Anabaena sp. strain PCC 7120. Here, we show that rapid microevolution is under way in this strain, leading to phenotypic variations for certain genes related to heterocyst development, such as hetC This study provides an example for ongoing microevolution, marked by multiple heterogeneous/heterozygous single nucleotide polymorphisms (SNPs), in a multicellular multicopy-genome microorganism.
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49
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Popova AA, Rasmussen U, Semashko TA, Govorun VM, Koksharova OA. Stress effects of cyanotoxin β-methylamino-L-alanine (BMAA) on cyanobacterial heterocyst formation and functionality. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:369-377. [PMID: 29624906 DOI: 10.1111/1758-2229.12647] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/28/2018] [Accepted: 04/01/2018] [Indexed: 06/08/2023]
Abstract
Various species of cyanobacteria, diatoms and dinoflagellates are capable of synthesizing the non-proteinogenic neurotoxic amino acid β-N-methylamino-L-alanine (BMAA), which is known to be a causative agent of human neurodegeneration. Similar to most cyanotoxins, the biological and ecological functions of BMAA in cyanobacteria are unknown. In this study, we show for the first time that BMAA, in micromolar amounts, inhibits the formation of heterocysts (specialized nitrogen-fixing cells) in heterocystous, diazotrophic cyanobacteria [Anabaena sp. PCC 7120, Nostoc punctiforme PCC 73102 (ATCC 29133), Nostoc sp. strain 8963] under conditions of nitrogen starvation. The inhibitory effect of BMAA is abolished by the addition of glutamate. To understand the genetic reason for the observed phenomenon, we used qPCR to study the expression of key genes involved in cell differentiation and nitrogen metabolism in the model cyanobacterium Anabaena sp. PCC 7120. We observed that in the presence of BMAA, Anabaena sp. PCC 7120 does not express two essential genes associated with heterocyst differentiation, namely, hetR and hepA. We also found that addition of BMAA to cyanobacterial cultures with mature heterocysts inhibits nifH gene expression and nitrogenase activity.
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Affiliation(s)
- Alexandra A Popova
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square, 2, 123182 Moscow, Russia
| | - Ulla Rasmussen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden
| | - Tatiana A Semashko
- Scientific-Research Institute of Physical-Chemical Medicine, Moscow 119435, Russia
| | - Vadim M Govorun
- Scientific-Research Institute of Physical-Chemical Medicine, Moscow 119435, Russia
| | - Olga A Koksharova
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square, 2, 123182 Moscow, Russia
- Lomonosov Moscow State University, Belozersky Institute of Physical-Chemical Biology, Leninskie Gory, 1, 40, Moscow, 119992, Russia
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Avilan L, Roumezi B, Risoul V, Bernard CS, Kpebe A, Belhadjhassine M, Rousset M, Brugna M, Latifi A. Phototrophic hydrogen production from a clostridial [FeFe] hydrogenase expressed in the heterocysts of the cyanobacterium Nostoc PCC 7120. Appl Microbiol Biotechnol 2018; 102:5775-5783. [DOI: 10.1007/s00253-018-8989-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 03/11/2018] [Accepted: 04/05/2018] [Indexed: 12/28/2022]
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