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Yamane M, Osanai T. Nondiazotrophic cyanobacteria metabolic engineering for succinate and lactate production. ALGAL RES 2023. [DOI: 10.1016/j.algal.2023.103088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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2
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Robles-Rengel R, Florencio FJ, Muro-Pastor MI. Redox interference in nitrogen status via oxidative stress is mediated by 2-oxoglutarate in cyanobacteria. THE NEW PHYTOLOGIST 2019; 224:216-228. [PMID: 31168850 DOI: 10.1111/nph.15979] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 05/30/2019] [Indexed: 05/10/2023]
Abstract
Reactive oxygen species (ROS) are generated naturally in photosynthetic organisms by respiration and photosynthesis. Therefore, detoxification of these compounds, avoiding oxidative stress, is essential for proper cell function. In cyanobacteria, some observations point to a crosstalk between ROS homeostasis, in particular hydrogen peroxide, and nitrogen metabolism by a mechanism independent of known redox regulators. Using glutamine synthetase (GS), a finely regulated enzyme essential for nitrogen assimilation, as a tool, we were able to monitor nitrogen metabolism in relation to oxidative stress. We show that hydrogen peroxide clearly alters the expression of different genes related to nitrogen metabolism, both in the wild-type strain of the cyanobacterium Synechocystis sp. PCC 6803 and in a mutant strain lacking the catalase-peroxidase encoded by the katG gene and therefore highly sensitive to oxidative stress. As cyanobacteria perceive nitrogen status by sensing intracellular 2-oxoglutarate (2-OG) concentrations, the hydrogen peroxide effect was analysed under different nitrogen conditions in the wild-type, the ∆katG strain and in a strain able to transport 2-OG. The results obtained demonstrate that hydrogen peroxide interferes with signalling of cellular carbon : nitrogen status by decreasing the intracellular concentrations of 2-OG and hence altering the function of the 2-OG-sensing global nitrogen regulator NtcA.
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Affiliation(s)
- Rocío Robles-Rengel
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Sevilla, 41092, Spain
| | - Francisco J Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Sevilla, 41092, Spain
| | - M Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Sevilla, 41092, Spain
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3
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Ishikawa Y, Kawai-Yamada M. Physiological Significance of NAD Kinases in Cyanobacteria. FRONTIERS IN PLANT SCIENCE 2019; 10:847. [PMID: 31316540 PMCID: PMC6610520 DOI: 10.3389/fpls.2019.00847] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 06/13/2019] [Indexed: 05/04/2023]
Abstract
Unicellular cyanobacteria are thought to be the evolutionary ancestors of plant chloroplasts and are widely used both for chemical production and as model organisms in studies of photosynthesis. Although most research focused on increasing reducing power (that is, NADPH) as target of metabolic engineering, the physiological roles of NAD(P)(H) in cyanobacteria poorly understood. In cyanobacteria such as the model species Synechocystis sp. PCC 6803, most metabolic pathways share a single compartment. This complex metabolism raises the question of how cyanobacteria control the amounts of the redox pairs NADH/NAD+ and NADPH/NADP+ in the cyanobacterial metabolic pathways. For example, photosynthetic and respiratory electron transport chains share several redox components in the thylakoid lumen, including plastoquinone, cytochrome b6f (cyt b6f), and the redox carriers plastocyanin and cytochrome c6. In the case of photosynthesis, NADP+ acts as an important electron mediator on the acceptor-side of photosystem I (PSI) in the linear electron chain as well as in the plant chloroplast. Meanwhile, in respiration, most electrons derived from NADPH and NADH are transferred by NAD(P)H dehydrogenases. Therefore, it is expected that Synechocystis employs unique NAD(P)(H) -pool control mechanisms to regulate the mixed metabolic systems involved in photosynthesis and respiration. This review article summarizes the current state of knowledge of NAD(P)(H) metabolism in Synechocystis. In particular, we focus on the physiological function in Synechocystis of NAD kinase, the enzyme that phosphorylates NAD+ to NADP+.
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4
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Kube M, Jefferson B, Fan L, Roddick F. The impact of wastewater characteristics, algal species selection and immobilisation on simultaneous nitrogen and phosphorus removal. ALGAL RES 2018. [DOI: 10.1016/j.algal.2018.01.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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5
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Esteves-Ferreira AA, Inaba M, Fort A, Araújo WL, Sulpice R. Nitrogen metabolism in cyanobacteria: metabolic and molecular control, growth consequences and biotechnological applications. Crit Rev Microbiol 2018. [DOI: 10.1080/1040841x.2018.1446902] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Alberto A. Esteves-Ferreira
- National University of Ireland – Galway, Plant Systems Biology Lab, School of Natural Sciences, Plant and AgriBiosciences Research Centre, Galway, Ireland
- CAPES Foundation, Ministry of Education of Brazil, Brasilia, Brazil
| | - Masami Inaba
- National University of Ireland – Galway, Plant Systems Biology Lab, School of Natural Sciences, Plant and AgriBiosciences Research Centre, Galway, Ireland
| | - Antoine Fort
- National University of Ireland – Galway, Plant Systems Biology Lab, School of Natural Sciences, Plant and AgriBiosciences Research Centre, Galway, Ireland
| | - Wagner L. Araújo
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Ronan Sulpice
- National University of Ireland – Galway, Plant Systems Biology Lab, School of Natural Sciences, Plant and AgriBiosciences Research Centre, Galway, Ireland
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Asplund-Samuelsson J, Janasch M, Hudson EP. Thermodynamic analysis of computed pathways integrated into the metabolic networks of E. coli and Synechocystis reveals contrasting expansion potential. Metab Eng 2017; 45:223-236. [PMID: 29278749 DOI: 10.1016/j.ymben.2017.12.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 12/04/2017] [Accepted: 12/20/2017] [Indexed: 01/09/2023]
Abstract
Introducing biosynthetic pathways into an organism is both reliant on and challenged by endogenous biochemistry. Here we compared the expansion potential of the metabolic network in the photoautotroph Synechocystis with that of the heterotroph E. coli using the novel workflow POPPY (Prospecting Optimal Pathways with PYthon). First, E. coli and Synechocystis metabolomic and fluxomic data were combined with metabolic models to identify thermodynamic constraints on metabolite concentrations (NET analysis). Then, thousands of automatically constructed pathways were placed within each network and subjected to a network-embedded variant of the max-min driving force analysis (NEM). We found that the networks had different capabilities for imparting thermodynamic driving forces toward certain compounds. Key metabolites were constrained differently in Synechocystis due to opposing flux directions in glycolysis and carbon fixation, the forked tri-carboxylic acid cycle, and photorespiration. Furthermore, the lysine biosynthesis pathway in Synechocystis was identified as thermodynamically constrained, impacting both endogenous and heterologous reactions through low 2-oxoglutarate levels. Our study also identified important yet poorly covered areas in existing metabolomics data and provides a reference for future thermodynamics-based engineering in Synechocystis and beyond. The POPPY methodology represents a step in making optimal pathway-host matches, which is likely to become important as the practical range of host organisms is diversified.
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Affiliation(s)
- Johannes Asplund-Samuelsson
- Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, P-Box 1031, 171 21 Solna, Sweden.
| | - Markus Janasch
- Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, P-Box 1031, 171 21 Solna, Sweden.
| | - Elton P Hudson
- Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, P-Box 1031, 171 21 Solna, Sweden.
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Giner-Lamia J, Robles-Rengel R, Hernández-Prieto MA, Muro-Pastor MI, Florencio FJ, Futschik ME. Identification of the direct regulon of NtcA during early acclimation to nitrogen starvation in the cyanobacterium Synechocystis sp. PCC 6803. Nucleic Acids Res 2017; 45:11800-11820. [PMID: 29036481 PMCID: PMC5714215 DOI: 10.1093/nar/gkx860] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 09/15/2017] [Indexed: 12/22/2022] Open
Abstract
In cyanobacteria, nitrogen homeostasis is maintained by an intricate regulatory network around transcription factor NtcA. Although mechanisms controlling NtcA activity appear to be well understood, its regulon remains poorly defined. To determine the NtcA regulon during the early stages of nitrogen starvation for the model cyanobacterium Synechocystis sp. PCC 6803, we performed chromatin immunoprecipitation, followed by sequencing (ChIP-seq), in parallel with transcriptome analysis (RNA-seq). Through combining these methods, we determined 51 genes activated and 28 repressed directly by NtcA. In addition to genes associated with nitrogen and carbon metabolism, a considerable number of genes without current functional annotation were among direct targets providing a rich reservoir for further studies. The NtcA regulon also included eight non-coding RNAs, of which Ncr1071, Syr6 and NsiR7 were experimentally validated, and their putative targets were computationally predicted. Surprisingly, we found substantial NtcA binding associated with delayed expression changes indicating that NtcA can reside in a poised state controlled by other factors. Indeed, a role of PipX as modulating factor in nitrogen regulation was confirmed for selected NtcA-targets. We suggest that the indicated poised state of NtcA enables a more differentiated response to nitrogen limitation and can be advantageous in native habitats of Synechocystis.
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Affiliation(s)
- Joaquín Giner-Lamia
- Systems Biology and Bioinformatics Laboratory, CBMR, University of Algarve, 8005-139 Faro, Portugal.,Laboratory of Intracellular Bacterial Pathogens, Department of Microbial Biotechnology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain
| | - Rocío Robles-Rengel
- Instituto de Bioquímica Vegetal y Fotosíntesis. Universidad de Sevilla-CSIC, Av. Américo Vespucio 49, E-41092 Seville, Spain
| | - Miguel A Hernández-Prieto
- Systems Biology and Bioinformatics Laboratory, CBMR, University of Algarve, 8005-139 Faro, Portugal.,ARC Centre of Excellence for Translational Photosynthesis and School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia
| | - M Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis. Universidad de Sevilla-CSIC, Av. Américo Vespucio 49, E-41092 Seville, Spain
| | - Francisco J Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis. Universidad de Sevilla-CSIC, Av. Américo Vespucio 49, E-41092 Seville, Spain
| | - Matthias E Futschik
- Systems Biology and Bioinformatics Laboratory, CBMR, University of Algarve, 8005-139 Faro, Portugal.,Centre of Marine Sciences (CCMAR), University of Algarve, 8005-139 Faro, Portugal.,School of Biomedical & Healthcare Sciences, Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth PL6 8BU, UK
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8
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Esteves-Ferreira AA, Cavalcanti JHF, Vaz MGMV, Alvarenga LV, Nunes-Nesi A, Araújo WL. Cyanobacterial nitrogenases: phylogenetic diversity, regulation and functional predictions. Genet Mol Biol 2017; 40:261-275. [PMID: 28323299 PMCID: PMC5452144 DOI: 10.1590/1678-4685-gmb-2016-0050] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 12/21/2016] [Indexed: 12/21/2022] Open
Abstract
Cyanobacteria is a remarkable group of prokaryotic photosynthetic microorganisms, with several genera capable of fixing atmospheric nitrogen (N2) and presenting a wide range of morphologies. Although the nitrogenase complex is not present in all cyanobacterial taxa, it is spread across several cyanobacterial strains. The nitrogenase complex has also a high theoretical potential for biofuel production, since H2 is a by-product produced during N2 fixation. In this review we discuss the significance of a relatively wide variety of cell morphologies and metabolic strategies that allow spatial and temporal separation of N2 fixation from photosynthesis in cyanobacteria. Phylogenetic reconstructions based on 16S rRNA and nifD gene sequences shed light on the evolutionary history of the two genes. Our results demonstrated that (i) sequences of genes involved in nitrogen fixation (nifD) from several morphologically distinct strains of cyanobacteria are grouped in similarity with their morphology classification and phylogeny, and (ii) nifD genes from heterocytous strains share a common ancestor. By using this data we also discuss the evolutionary importance of processes such as horizontal gene transfer and genetic duplication for nitrogenase evolution and diversification. Finally, we discuss the importance of H2 synthesis in cyanobacteria, as well as strategies and challenges to improve cyanobacterial H2 production.
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Affiliation(s)
- Alberto A Esteves-Ferreira
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil.,Max-Planck-partner group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - João Henrique Frota Cavalcanti
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil.,Max-Planck-partner group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Marcelo Gomes Marçal Vieira Vaz
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil.,Max-Planck-partner group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Luna V Alvarenga
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil.,Max-Planck-partner group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Adriano Nunes-Nesi
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil.,Max-Planck-partner group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Wagner L Araújo
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil.,Max-Planck-partner group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
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9
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Immethun CM, DeLorenzo DM, Focht CM, Gupta D, Johnson CB, Moon TS. Physical, chemical, and metabolic state sensors expand the synthetic biology toolbox for Synechocystis sp. PCC 6803. Biotechnol Bioeng 2017; 114:1561-1569. [PMID: 28244586 DOI: 10.1002/bit.26275] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 01/19/2017] [Accepted: 02/19/2017] [Indexed: 02/04/2023]
Abstract
Many under-developed organisms possess important traits that can boost the effectiveness and sustainability of microbial biotechnology. Photoautotrophic cyanobacteria can utilize the energy captured from light to fix carbon dioxide for their metabolic needs while living in environments not suited for growing crops. Various value-added compounds have been produced by cyanobacteria in the laboratory; yet, the products' titers and yields are often not industrially relevant and lag behind what have been accomplished in heterotrophic microbes. Genetic tools for biological process control are needed to take advantage of cyanobacteria's beneficial qualities, as tool development also lags behind what has been created in common heterotrophic hosts. To address this problem, we developed a suite of sensors that regulate transcription in the model cyanobacterium Synechocystis sp. PCC 6803 in response to metabolically relevant signals, including light and the cell's nitrogen status, and a family of sensors that respond to the inexpensive chemical, l-arabinose. Increasing the number of available tools enables more complex and precise control of gene expression. Expanding the synthetic biology toolbox for this cyanobacterium also improves our ability to utilize this important under-developed organism in biotechnology. Biotechnol. Bioeng. 2017;114: 1561-1569. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Cheryl M Immethun
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Drew M DeLorenzo
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Caroline M Focht
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Dinesh Gupta
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Charles B Johnson
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Tae Seok Moon
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
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Singh S, Mishra AK. Unraveling of cross talk between Ca(2+) and ROS regulating enzymes in Anabaena 7120 and ntcA mutant. J Basic Microbiol 2015; 56:762-78. [PMID: 26374944 DOI: 10.1002/jobm.201500326] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 08/09/2015] [Indexed: 01/25/2023]
Abstract
In order to understand a cross talk between Ca(2+) and ROS regulating enzymes and the possible involvement of ntcA gene, Anabaena sp. PCC 7120 and its derivative ntcA mutant grown in varied levels of calcium chloride (0, 1, 10, and 100 mM) have been investigated. Scanning Electron Microscopy showed abnormal structure formation at high calcium concentration (100 mM) both in wild type and mutant. Fv /Fm values suggested that 100 mM calcium concentration was detrimental for photosynthetic apparatus. SOD, catalase, APX, GR, and peroxidase activity were found to be maximum for 100 mM and minimum for 1 mM of exogenously supplied calcium salt. NADPH contents were higher for wild type than mutant. RAPD-PCR and SDS-PAGE analysis revealed a difference in DNA as well as proteome pattern with changes in calcium chloride regime. Prominent bands of approximately 70, 33, 21, and 14 kDa expressed in the wild type served as the marker polypeptide bands under calcium supplementation. Results suggest that higher levels of calcium ion disturb the cellular homeostasis generating ROS, thereby inducing enhanced levels of antioxidative enzymes. Further, data also suggests possible involvement of ntcA gene in cross talk between calcium ion and ROS regulating enzymes.
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Affiliation(s)
- Savita Singh
- Department of Botany, Laboratory of Microbial Genetics, Banaras Hindu University, Varanasi, India
| | - Arun Kumar Mishra
- Department of Botany, Laboratory of Microbial Genetics, Banaras Hindu University, Varanasi, India
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11
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One day of nitrogen starvation reveals the effect of sigE and rre37 overexpression on the expression of genes related to carbon and nitrogen metabolism in Synechocystis sp. PCC 6803. J Biosci Bioeng 2015; 120:128-34. [DOI: 10.1016/j.jbiosc.2014.12.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 12/19/2014] [Accepted: 12/20/2014] [Indexed: 01/08/2023]
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12
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rre37 Overexpression alters gene expression related to the tricarboxylic acid cycle and pyruvate metabolism in Synechocystis sp. PCC 6803. ScientificWorldJournal 2014; 2014:921976. [PMID: 25614900 PMCID: PMC4295605 DOI: 10.1155/2014/921976] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/22/2014] [Accepted: 11/23/2014] [Indexed: 11/23/2022] Open
Abstract
The tricarboxylic acid (TCA) cycle and pyruvate metabolism of cyanobacteria are unique and important from the perspectives of biology and biotechnology research. Rre37, a response regulator induced by nitrogen depletion, activates gene expression related to sugar catabolism. Our previous microarray analysis has suggested that Rre37 controls the transcription of genes involved in sugar catabolism, pyruvate metabolism, and the TCA cycle. In this study, quantitative real-time PCR was used to measure the transcript levels of 12 TCA cycle genes and 13 pyruvate metabolism genes. The transcripts of 6 genes (acnB, icd, ppc, pyk1, me, and pta) increased after 4 h of nitrogen depletion in the wild-type GT strain but the induction was abolished by rre37 overexpression. The repression of gene expression of fumC, ddh, and ackA caused by nitrogen depletion was abolished by rre37 overexpression. The expression of me was differently affected by rre37 overexpression, compared to the other 24 genes. These results indicate that Rre37 differently controls the genes of the TCA cycle and pyruvate metabolism, implying the key reaction of the primary in this unicellular cyanobacterium.
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Domínguez-Martín MA, López-Lozano A, Diez J, Gómez-Baena G, Rangel-Zúñiga OA, García-Fernández JM. Physiological regulation of isocitrate dehydrogenase and the role of 2-oxoglutarate in Prochlorococcus sp. strain PCC 9511. PLoS One 2014; 9:e103380. [PMID: 25061751 PMCID: PMC4111581 DOI: 10.1371/journal.pone.0103380] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 07/02/2014] [Indexed: 01/05/2023] Open
Abstract
The enzyme isocitrate dehydrogenase (ICDH; EC 1.1.1.42) catalyzes the oxidative decarboxylation of isocitrate, to produce 2-oxoglutarate. The incompleteness of the tricarboxylic acids cycle in marine cyanobacteria confers a special importance to isocitrate dehydrogenase in the C/N balance, since 2-oxoglutarate can only be metabolized through the glutamine synthetase/glutamate synthase pathway. The physiological regulation of isocitrate dehydrogenase was studied in cultures of Prochlorococcus sp. strain PCC 9511, by measuring enzyme activity and concentration using the NADPH production assay and Western blotting, respectively. The enzyme activity showed little changes under nitrogen or phosphorus starvation, or upon addition of the inhibitors DCMU, DBMIB and MSX. Azaserine, an inhibitor of glutamate synthase, induced clear increases in the isocitrate dehydrogenase activity and icd gene expression after 24 h, and also in the 2-oxoglutarate concentration. Iron starvation had the most significant effect, inducing a complete loss of isocitrate dehydrogenase activity, possibly mediated by a process of oxidative inactivation, while its concentration was unaffected. Our results suggest that isocitrate dehydrogenase responds to changes in the intracellular concentration of 2-oxoglutarate and to the redox status of the cells in Prochlorococcus.
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Affiliation(s)
| | - Antonio López-Lozano
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
| | - Jesús Diez
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
| | - Guadalupe Gómez-Baena
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
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Schwarz D, Orf I, Kopka J, Hagemann M. Effects of Inorganic Carbon Limitation on the Metabolome of the Synechocystis sp. PCC 6803 Mutant Defective in glnB Encoding the Central Regulator PII of Cyanobacterial C/N Acclimation. Metabolites 2014; 4:232-47. [PMID: 24957024 PMCID: PMC4101504 DOI: 10.3390/metabo4020232] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 04/14/2014] [Accepted: 04/16/2014] [Indexed: 11/27/2022] Open
Abstract
Cyanobacteria are the only prokaryotes performing oxygenic photosynthesis. Non-diazotrophic strains such as the model Synechocystis sp. PCC 6803 depend on a balanced uptake and assimilation of inorganic carbon and nitrogen sources. The internal C/N ratio is sensed via the PII protein (GlnB). We analyzed metabolic changes of the ΔglnB mutant of Synechocystis sp. PCC 6803 under different CO2 availability. The identified metabolites provided a snapshot of the central C/N metabolism. Cells of the ΔglnB mutant shifted to carbon-limiting conditions, i.e. a decreased C/N ratio, showed changes in intermediates of the sugar storage and particularly of the tricarboxylic acid cycle, arginine, and glutamate metabolism. The changes of the metabolome support the notion that the PII protein is primarily regulating the N-metabolism whereas the changes in C-metabolism are probably secondary effects of the PII deletion.
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Affiliation(s)
- Doreen Schwarz
- Universität Rostock, Institut Biowissenschaften, Pflanzenphysiologie, Albert-Einstein-Str. 3, D-18059 Rostock, Germany.
| | - Isabel Orf
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Golm, Germany.
| | - Joachim Kopka
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Golm, Germany.
| | - Martin Hagemann
- Universität Rostock, Institut Biowissenschaften, Pflanzenphysiologie, Albert-Einstein-Str. 3, D-18059 Rostock, Germany.
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Omairi-Nasser A, Galmozzi CV, Latifi A, Muro-Pastor MI, Ajlani G. NtcA is responsible for accumulation of the small isoform of ferredoxin:NADP oxidoreductase. Microbiology (Reading) 2014; 160:789-794. [DOI: 10.1099/mic.0.076042-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In several cyanobacteria, petH, the gene encoding ferredoxin:NADP oxidoreductase (FNR), is transcribed from at least two promoters depending on growth conditions. Two transcripts (short and long) are translated from two different translation initiation sites, resulting in two isoforms (large and small, respectively). Here, we show that in Synechocystis PCC6803 the global transcriptional regulator NtcA activates transcription from the distal petH promoter. Modification of the NtcA-binding site prevents NtcA binding to the promoter in vitro and abolishes accumulation of the small isoform of FNR in vivo. We also demonstrate that a similar petH transcription and translation regime occurs in other cyanobacteria. The conditions under which this system operates provide hints for the function of each FNR isoform.
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Affiliation(s)
- Amin Omairi-Nasser
- Institut de Biologie et de Technologie de Saclay, Centre National de la Recherche Scientifique and Commissariat à l’Energie Atomique, 91191 Gif-sur-Yvette, France
| | - Carla V. Galmozzi
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Américo Vespucio 49, 41092 Seville, Spain
| | - Amel Latifi
- Aix-Marseille Université, Laboratoire de Chimie Bactérienne, Centre National de la Recherche Scientifique, 31 chemin J. Aiguier, 13009 Marseille, France
| | - M. Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Américo Vespucio 49, 41092 Seville, Spain
| | - Ghada Ajlani
- Institut de Biologie et de Technologie de Saclay, Centre National de la Recherche Scientifique and Commissariat à l’Energie Atomique, 91191 Gif-sur-Yvette, France
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Vaishampayan A, Sinha RP, Häder DP. Use of Genetically Improved Nitrogen-Fixing Cyanobacteria in Rice Paddy Fields: Prospects as a Source Material for Engineering Herbicide Sensitivity and Resistance in Plants. ACTA ACUST UNITED AC 2014. [DOI: 10.1111/j.1438-8677.1998.tb00693.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Rre37 stimulates accumulation of 2-oxoglutarate and glycogen under nitrogen starvation in Synechocystis sp. PCC 6803. FEBS Lett 2013; 588:466-71. [PMID: 24374346 DOI: 10.1016/j.febslet.2013.12.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 12/10/2013] [Accepted: 12/11/2013] [Indexed: 11/21/2022]
Abstract
Rre37 (sll1330) in a cyanobacterium Synechocystis sp. PCC 6803 acts as a regulatory protein for sugar catabolic genes during nitrogen starvation. Low glycogen accumulation in Δrre37 was due to low expression of glycogen anabolic genes. In addition to low 2-oxoglutarate accumulation, normal upregulated expression of genes encoding glutamate synthases (gltD and gltB) as well as accumulation of metabolites in glycolysis (fructose-6-phosphate, fructose-1,6-bisphosphate, and glyceraldehyde-3-phosphate) and tricarboxylic acid (TCA) cycle (oxaloacetate, fumarate, succinate, and aconitate) were abolished by rre37 knockout. Rre37 regulates 2-oxoglutarate accumulation, glycogen accumulation through expression of glycogen anabolic genes, and TCA cycle metabolites accumulation.
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Jacobsen JH, Frigaard NU. Engineering of photosynthetic mannitol biosynthesis from CO2 in a cyanobacterium. Metab Eng 2013; 21:60-70. [PMID: 24269997 DOI: 10.1016/j.ymben.2013.11.004] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 10/16/2013] [Accepted: 11/11/2013] [Indexed: 11/24/2022]
Abstract
D-Mannitol (hereafter denoted mannitol) is used in the medical and food industry and is currently produced commercially by chemical hydrogenation of fructose or by extraction from seaweed. Here, the marine cyanobacterium Synechococcus sp. PCC 7002 was genetically modified to photosynthetically produce mannitol from CO2 as the sole carbon source. Two codon-optimized genes, mannitol-1-phosphate dehydrogenase (mtlD) from Escherichia coli and mannitol-1-phosphatase (mlp) from the protozoan chicken parasite Eimeria tenella, in combination encoding a biosynthetic pathway from fructose-6-phosphate to mannitol, were expressed in the cyanobacterium resulting in accumulation of mannitol in the cells and in the culture medium. The mannitol biosynthetic genes were expressed from a single synthetic operon inserted into the cyanobacterial chromosome by homologous recombination. The mannitol biosynthesis operon was constructed using a novel uracil-specific excision reagent (USER)-based polycistronic expression system characterized by ligase-independent, directional cloning of the protein-encoding genes such that the insertion site was regenerated after each cloning step. Genetic inactivation of glycogen biosynthesis increased the yield of mannitol presumably by redirecting the metabolic flux to mannitol under conditions where glycogen normally accumulates. A total mannitol yield equivalent to 10% of cell dry weight was obtained in cell cultures synthesizing glycogen while the yield increased to 32% of cell dry weight in cell cultures deficient in glycogen synthesis; in both cases about 75% of the mannitol was released from the cells into the culture medium by an unknown mechanism. The highest productivity was obtained in a glycogen synthase deficient culture that after 12 days showed a mannitol concentration of 1.1 g mannitol L(-1) and a production rate of 0.15 g mannitol L(-1) day(-1). This system may be useful for biosynthesis of valuable sugars and sugar derivatives from CO2 in cyanobacteria.
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Affiliation(s)
- Jacob H Jacobsen
- Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Niels-Ulrik Frigaard
- Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark.
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Kaniya Y, Kizawa A, Miyagi A, Kawai-Yamada M, Uchimiya H, Kaneko Y, Nishiyama Y, Hihara Y. Deletion of the transcriptional regulator cyAbrB2 deregulates primary carbon metabolism in Synechocystis sp. PCC 6803. PLANT PHYSIOLOGY 2013; 162:1153-63. [PMID: 23589835 PMCID: PMC3668046 DOI: 10.1104/pp.113.218784] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 04/12/2013] [Indexed: 05/21/2023]
Abstract
cyAbrB is a transcriptional regulator unique to and highly conserved among cyanobacterial species. A gene-disrupted mutant of cyabrB2 (sll0822) in Synechocystis sp. PCC 6803 exhibited severe growth inhibition and abnormal accumulation of glycogen granules within cells under photomixotrophic conditions. Within 6 h after the shift to photomixotrophic conditions, sodium bicarbonate-dependent oxygen evolution activity markedly declined in the ΔcyabrB2 mutant, but the decrease in methyl viologen-dependent electron transport activity was much smaller, indicating inhibition in carbon dioxide fixation. Decreases in the transcript levels of several genes related to sugar catabolism, carbon dioxide fixation, and nitrogen metabolism were also observed within 6 h. Metabolome analysis by capillary electrophoresis mass spectrometry revealed that several metabolites accumulated differently in the wild-type and mutant strains. For example, the amounts of pyruvate and 2-oxoglutarate (2OG) were significantly lower in the mutant than in the wild type, irrespective of trophic conditions. The growth rate of the ΔcyabrB2 mutant was restored to a level comparable to that under photoautotrophic conditions by addition of 2OG to the growth medium under photomixotrophic conditions. Activities of various metabolic processes, including carbon dioxide fixation, respiration, and nitrogen assimilation, seemed to be enhanced by 2OG addition. These observations suggest that cyAbrB2 is essential for the active transcription of genes related to carbon and nitrogen metabolism upon a shift to photomixotrophic conditions. Deletion of cyAbrB2 is likely to deregulate the partition of carbon between storage forms and soluble forms used for biosynthetic purposes. This disorder may cause inactivation of cellular metabolism, excess accumulation of reducing equivalents, and subsequent loss of viability under photomixotrophic conditions.
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Functional relevance of dynamic properties of Dimeric NADP-dependent Isocitrate Dehydrogenases. BMC Bioinformatics 2012; 13 Suppl 17:S2. [PMID: 23281650 PMCID: PMC3521221 DOI: 10.1186/1471-2105-13-s17-s2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background Isocitrate Dehydrogenases (IDHs) are important enzymes present in all living cells. Three subfamilies of functionally dimeric IDHs (subfamilies I, II, III) are known. Subfamily I are well-studied bacterial IDHs, like that of Escherischia coli. Subfamily II has predominantly eukaryotic members, but it also has several bacterial members, many being pathogens or endosymbionts. subfamily III IDHs are NAD-dependent. The eukaryotic-like subfamily II IDH from pathogenic bacteria such as Mycobacterium tuberculosis IDH1 are expected to have regulation similar to that of bacteria which use the glyoxylate bypass to survive starvation. Yet they are structurally different from IDHs of subfamily I, such as the E. coli IDH. Results We have used phylogeny, structural comparisons and molecular dynamics simulations to highlight the similarity and differences between NADP-dependent dimeric IDHs with an emphasis on regulation. Our phylogenetic study indicates that an additional subfamily (IV) may also be present. Variation in sequence and structure in an aligned region may indicate functional importance concerning regulation in bacterial subfamily I IDHs. Correlation in movement of prominent loops seen from molecular dynamics may explain the adaptability and diversity of the predominantly eukaryotic subfamily II IDHs. Conclusion This study discusses possible regulatory mechanisms operating in various IDHs and implications for regulation of eukaryotic-like bacterial IDHs such as that of M. tuberculosis, which may provide avenues for intervention in disease.
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Saha R, Verseput AT, Berla BM, Mueller TJ, Pakrasi HB, Maranas CD. Reconstruction and comparison of the metabolic potential of cyanobacteria Cyanothece sp. ATCC 51142 and Synechocystis sp. PCC 6803. PLoS One 2012; 7:e48285. [PMID: 23133581 PMCID: PMC3487460 DOI: 10.1371/journal.pone.0048285] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 09/21/2012] [Indexed: 12/02/2022] Open
Abstract
Cyanobacteria are an important group of photoautotrophic organisms that can synthesize valuable bio-products by harnessing solar energy. They are endowed with high photosynthetic efficiencies and diverse metabolic capabilities that confer the ability to convert solar energy into a variety of biofuels and their precursors. However, less well studied are the similarities and differences in metabolism of different species of cyanobacteria as they pertain to their suitability as microbial production chassis. Here we assemble, update and compare genome-scale models (iCyt773 and iSyn731) for two phylogenetically related cyanobacterial species, namely Cyanothece sp. ATCC 51142 and Synechocystis sp. PCC 6803. All reactions are elementally and charge balanced and localized into four different intracellular compartments (i.e., periplasm, cytosol, carboxysome and thylakoid lumen) and biomass descriptions are derived based on experimental measurements. Newly added reactions absent in earlier models (266 and 322, respectively) span most metabolic pathways with an emphasis on lipid biosynthesis. All thermodynamically infeasible loops are identified and eliminated from both models. Comparisons of model predictions against gene essentiality data reveal a specificity of 0.94 (94/100) and a sensitivity of 1 (19/19) for the Synechocystis iSyn731 model. The diurnal rhythm of Cyanothece 51142 metabolism is modeled by constructing separate (light/dark) biomass equations and introducing regulatory restrictions over light and dark phases. Specific metabolic pathway differences between the two cyanobacteria alluding to different bio-production potentials are reflected in both models.
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Affiliation(s)
- Rajib Saha
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Alex T. Verseput
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Bertram M. Berla
- Department of Energy, Environmental, and Chemical Engineering, Washington University, St. Louis, Missouri, United States of America
| | - Thomas J. Mueller
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Himadri B. Pakrasi
- Department of Energy, Environmental, and Chemical Engineering, Washington University, St. Louis, Missouri, United States of America
- Department of Biology, Washington University, St. Louis, Missouri, United States of America
| | - Costas D. Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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22
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Paerl RW, Tozzi S, Kolber ZS, Zehr JP. VARIATION IN THE ABUNDANCE OF SYNECHOCOCCUS SP. CC9311 NARB MRNA RELATIVE TO CHANGES IN LIGHT, NITROGEN GROWTH CONDITIONS AND NITRATE ASSIMILATION(1). JOURNAL OF PHYCOLOGY 2012; 48:1028-1039. [PMID: 27009013 DOI: 10.1111/j.1529-8817.2012.01197.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Synechococcus- and Prochlorococcus-specific narB genes that encode for an assimilatory nitrate reductase are found in coastal to open-ocean waters. However, it remains uncertain if these picocyanobacteria assimilate nitrate in situ. This unknown can potentially be addressed by examining narB mRNA from the environment, but this requires a better understanding of the influence of environmental factors on narB gene transcription. In laboratory experiments with Synechococcus sp. CC9311 cultures exposed to diel light fluctuations and grown on nitrate or ammonium, there was periodic change in narB transcript abundance. This periodicity was broken in cultures subjected to a doubling of irradiance (40-80 μmol photons · m(-2) · s(-1) ) during the mid-light period. Therefore, the irradiance level, not circadian rhythm, was the dominant factor controlling narB transcription. In nitrate-grown cultures, diel change in narB transcript abundance and nitrate assimilation rate did not correlate; suggesting narB mRNA levels better indicate nitrate assimilation activity than assimilation rate. Growth history also affected narB transcription, as changes in narB mRNA levels in nitrogen-deprived CC9311 cultures following nitrate amendment were distinct from cultures grown solely on nitrate. Environmental sampling for narB transcripts should consider time, irradiance, and the growth status of cells to ecologically interpret narB transcript abundances.
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Affiliation(s)
- Ryan W Paerl
- Department of Ocean Sciences, University of California Santa Cruz, 1156 High Street EMS D446, Santa Cruz, CA 95064, USA
| | - Sasha Tozzi
- Department of Ocean Sciences, University of California Santa Cruz, 1156 High Street EMS D446, Santa Cruz, CA 95064, USA
| | - Zbigniew S Kolber
- Department of Ocean Sciences, University of California Santa Cruz, 1156 High Street EMS D446, Santa Cruz, CA 95064, USA
| | - Jonathan P Zehr
- Department of Ocean Sciences, University of California Santa Cruz, 1156 High Street EMS D446, Santa Cruz, CA 95064, USA
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23
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McDonagh B, Domínguez-Martín MA, Gómez-Baena G, López-Lozano A, Diez J, Bárcena JA, García Fernández JM. Nitrogen starvation induces extensive changes in the redox proteome of Prochlorococcus sp. strain SS120. ENVIRONMENTAL MICROBIOLOGY REPORTS 2012; 4:257-267. [PMID: 23757281 DOI: 10.1111/j.1758-2229.2012.00329.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Very low nitrogen concentration is a critical limitation in the oligotrophic oceans inhabited by the cyanobacterium Prochlorococccus, one of the main primary producers on Earth. It is well known that nitrogen starvation affects redox homeostasis in cells. We have studied the effect of nitrogen starvation on the thiol redox proteome in the Prochlorococcus sp. SS120 strain, by using shotgun proteomic techniques to map the cysteine modified in each case and to quantify the ratio of reversibly oxidized/reduced species. We identified a number of proteins showing modified cysteines only under either control or N-starvation, including isocitrate dehydrogenase and ribulose phosphate 3-epimerase. We detected other key enzymes, such as glutamine synthetase, transporters and transaminases, showing that nitrogen-related pathways were deeply affected by nitrogen starvation. Reversibly oxidized cysteines were also detected in proteins of other important metabolic pathways, such as photosynthesis, phosphorus metabolism, ATP synthesis and nucleic acids metabolism. Our results demonstrate a wide effect of nitrogen limitation on the redox status of the Prochlorococcus proteome, suggesting that besides previously reported transcriptional changes, this cyanobacterium responds with post-translational redox changes to the lack of nitrogen in its environment.
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Affiliation(s)
- Brian McDonagh
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Agroalimentario CEIA3, Universidad de Córdoba, Spain
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24
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Posttranscriptional regulation of glutamine synthetase in the filamentous Cyanobacterium Anabaena sp. PCC 7120: differential expression between vegetative cells and heterocysts. J Bacteriol 2010; 192:4701-11. [PMID: 20639319 DOI: 10.1128/jb.00222-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genes homologous to those implicated in glutamine synthetase (GS) regulation by protein-protein interaction in the cyanobacterium Synechocystis sp. strain PCC 6803 are conserved in several cyanobacterial sequenced genomes. We investigated this GS regulatory mechanism in Anabaena sp. strain PCC 7120. In this strain the system operates with only one GS inactivation factor (inactivation factor 7A [IF7A]), encoded by open reading frame (ORF) asl2329 (gifA). Following addition of ammonium, expression of gifA is derepressed, leading to the synthesis of IF7A, and consequently, GS is inactivated. Upon ammonium removal, the GS activity returns to the initial level and IF7A becomes undetectable. The global nitrogen control protein NtcA binds to the gifA promoter. Constitutive high expression levels of gifA were found in an Anabaena ntcA mutant (CSE2), indicating a repressor role for NtcA. In vitro studies demonstrate that Anabaena GS is not inactivated by Synechocystis IFs (IF7 and IF17), indicating the specificity of the system. We constructed an Anabaena strain expressing a second inactivating factor, containing the amino-terminal part of IF17 from Synechocystis fused to IF7A. GS inactivation in this strain is more effective than that in the wild type (WT) and resembles that observed in Synechocystis. Finally we found differential expression of the IF system between heterocysts and vegetative cells of Anabaena.
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25
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Ow SY, Noirel J, Cardona T, Taton A, Lindblad P, Stensjö K, Wright PC. Quantitative overview of N2 fixation in Nostoc punctiforme ATCC 29133 through cellular enrichments and iTRAQ shotgun proteomics. J Proteome Res 2009; 8:187-98. [PMID: 19012430 DOI: 10.1021/pr800285v] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nostoc punctiforme ATCC 29133 is a photoautotrophic cyanobacterium with the capacity to fix atmospheric N 2. Its ability to mediate this process is similar to that described for Nostoc sp. PCC 7120, where vegetative cells differentiate into heterocysts. Quantitative proteomic investigations at both the filament level and the heterocyst level are presented using isobaric tagging technology (iTRAQ), with 721 proteins at the 95% confidence interval quantified across both studies. Observations from both experiments yielded findings confirmatory of both transcriptional studies, and published Nostoc sp. PCC 7120 iTRAQ data. N. punctiforme exhibits similar metabolic trends, though changes in a number of metabolic pathways are less pronounced than in Nostoc sp. PCC 7120. Results also suggest a number of proteins that may benefit from future investigations. These include ATP dependent Zn-proteases, N-reserve degraders and also redox balance proteins. Complementary proteomic data sets from both organisms present key precursor knowledge that is important for future cyanobacterial biohydrogen research.
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Affiliation(s)
- Saw Yen Ow
- Biological & Environmental Systems Group, The University of Sheffield, Sheffield, S1 3JD, UK
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26
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López-Lozano A, Gómez-Baena G, Muñoz-Marín MDC, Rangel OA, Diez J, García-Fernández JM. Expression of genes involved in nitrogen assimilation and the C/N balance sensing in Prochlorococcus sp. strain SS120. Gene Expr 2009; 14:279-89. [PMID: 19630271 PMCID: PMC6042046 DOI: 10.3727/105221609788681204] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The expression of five genes involved in nitrogen assimilation in cyanobacteria, namely glnA, glsF, icd, ntcA, and glnB, encoding three key enzymes from that pathway (glutamine synthetase, glutamate synthase, isocitrate dehydrogenase) and two regulatory proteins (NtcA and PII), was studied in this work. Their changes under different conditions were analyzed by quantitative real-time RT-PCR. Nutrient limitation induced clear modifications on the expression of most studied genes: lack of nitrogen provoked an initial increase, followed by a marked decrease; in the cases of phosphorus and iron starvation, a general, stronger expression decrease was observed, particularly striking in the case of iron. Darkness and addition of the photosynthethic inhibitors DCMU and DBMIB also had a strong effect on gene expression. Methionine sulfoximine and azaserine, inhibitors of glutamine synthetase and glutamate synthase, respectively, provoked a sharp increase in icd expression. These results, together with previous studies, suggest that 2-oxoglutarate could be the molecule utilized by Prochlorococcus to sense the C/N balance. Besides, our results confirm the different regulation of nitrogen assimilation in Prochlorococcus with regard to other cyanobacteria.
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Affiliation(s)
- Antonio López-Lozano
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, 14071-Córdoba, Spain
| | - Guadalupe Gómez-Baena
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, 14071-Córdoba, Spain
| | | | - Oriol Alberto Rangel
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, 14071-Córdoba, Spain
| | - Jesús Diez
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, 14071-Córdoba, Spain
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27
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Transcription activation by NtcA and 2-oxoglutarate of three genes involved in heterocyst differentiation in the cyanobacterium Anabaena sp. strain PCC 7120. J Bacteriol 2008; 190:6126-33. [PMID: 18658268 DOI: 10.1128/jb.00787-08] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Anabaena sp. strain PCC 7120, differentiation of heterocysts takes place in response to the external cue of combined nitrogen deprivation, allowing the organism to fix atmospheric nitrogen in oxic environments. NtcA, a global transcriptional regulator of cyanobacteria, is required for activation of the expression of multiple genes involved in heterocyst differentiation, including key regulators that are specific to the process. We have set up a fully defined in vitro system, which includes the purified Anabaena RNA polymerase, and have studied the effects of NtcA and its signaling effector 2-oxoglutarate on RNA polymerase binding, open complex formation, and transcript production from promoters of the hetC, nrrA, and devB genes that are activated by NtcA at different stages of heterocyst differentiation. Both RNA polymerase and NtcA could specifically bind to the target DNA in the absence of any effector. 2-Oxoglutarate had a moderate positive effect on NtcA binding, and NtcA had a limited positive effect on RNA polymerase recruitment at the promoters. However, a stringent requirement of both NtcA and 2-oxoglutarate was observed for the detection of open complexes and transcript production at the three investigated promoters. These results support a key role for 2-oxoglutarate in transcription activation in the developing heterocyst.
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28
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Ow SY, Cardona T, Taton A, Magnuson A, Lindblad P, Stensjö K, Wright PC. Quantitative shotgun proteomics of enriched heterocysts from Nostoc sp. PCC 7120 using 8-plex isobaric peptide tags. J Proteome Res 2008; 7:1615-28. [PMID: 18290607 DOI: 10.1021/pr700604v] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The filamentous cyanobacterium Nostoc sp. strain PCC 7120 is capable of fixing atmospheric nitrogen. The labile nature of the core process requires the terminal differentiation of vegetative cells to form heterocysts, specialized cells with altered cellular and metabolic infrastructure to mediate the N2-fixing process. We present an investigation targeting the cellular proteomic expression of the heterocysts compared to vegetative cells of a population cultured under N2-fixing conditions. New 8-plex iTRAQ reagents were used on enriched replicate heterocyst and vegetative cells, and replicate N2-fixing and non-N2-fixing filaments to achieve accurate measurements. With this approach, we successfully identified 506 proteins, where 402 had confident quantifications. Observations provided by purified heterocyst analysis enabled the elucidation of the dominant metabolic processes between the respective cell types, while emphasis on the filaments enabled an overall comparison. The level of analysis provided by this investigation presents various tools and knowledge that are important for future development of cyanobacterial biohydrogen production.
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Affiliation(s)
- Saw Yen Ow
- Biological & Environmental Systems Group, Department of Chemical and Process Engineering, The University of Sheffield, Sheffield S13JD, UK
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29
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Muramatsu M, Hihara Y. Coordinated high-light response of genes encoding subunits of photosystem I is achieved by AT-rich upstream sequences in the cyanobacterium Synechocystis sp. strain PCC 6803. J Bacteriol 2007; 189:2750-8. [PMID: 17277074 PMCID: PMC1855792 DOI: 10.1128/jb.01903-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2006] [Accepted: 01/23/2007] [Indexed: 11/20/2022] Open
Abstract
Genes encoding subunits of photosystem I (PSI genes) in the cyanobacterium Synechocystis sp. strain PCC 6803 are actively transcribed under low-light conditions, whereas their transcription is coordinately and rapidly down-regulated upon the shift to high-light conditions. In order to identify the molecular mechanism of the coordinated high-light response, we searched for common light-responsive elements in the promoter region of PSI genes. First, the precise architecture of the psaD promoter was determined and compared with the previously identified structure of the psaAB promoter. One of two promoters of the psaAB genes (P1) and of the psaD gene (P2) possessed an AT-rich light-responsive element located just upstream of the basal promoter region. These sequences enhanced the basal promoter activity under low-light conditions, and their activity was transiently suppressed upon the shift to high-light conditions. Subsequent analysis of psaC, psaE, psaK1, and psaLI promoters revealed that their light response was also achieved by AT-rich sequences located at the -70 to -46 region. These results clearly show that AT-rich upstream elements are responsible for the coordinated high-light response of PSI genes dispersed throughout Synechocystis genome.
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Affiliation(s)
- Masayuki Muramatsu
- Department of Biochemistry and Molecular Biology, Faculty of Science, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan
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30
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Tolonen AC, Aach J, Lindell D, Johnson ZI, Rector T, Steen R, Church GM, Chisholm SW. Global gene expression of Prochlorococcus ecotypes in response to changes in nitrogen availability. Mol Syst Biol 2006; 2:53. [PMID: 17016519 PMCID: PMC1682016 DOI: 10.1038/msb4100087] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Accepted: 07/03/2006] [Indexed: 11/08/2022] Open
Abstract
Nitrogen (N) often limits biological productivity in the oceanic gyres where Prochlorococcus is the most abundant photosynthetic organism. The Prochlorococcus community is composed of strains, such as MED4 and MIT9313, that have different N utilization capabilities and that belong to ecotypes with different depth distributions. An interstrain comparison of how Prochlorococcus responds to changes in ambient nitrogen is thus central to understanding its ecology. We quantified changes in MED4 and MIT9313 global mRNA expression, chlorophyll fluorescence, and photosystem II photochemical efficiency (Fv/Fm) along a time series of increasing N starvation. In addition, the global expression of both strains growing in ammonium-replete medium was compared to expression during growth on alternative N sources. There were interstrain similarities in N regulation such as the activation of a putative NtcA regulon during N stress. There were also important differences between the strains such as in the expression patterns of carbon metabolism genes, suggesting that the two strains integrate N and C metabolism in fundamentally different ways.
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Affiliation(s)
- Andrew C Tolonen
- Department of Biology, MIT/WHOI Joint Program in Oceanography, Cambridge, MA, USA
| | - John Aach
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Debbie Lindell
- Department of Civil and Environmental Engineering, MIT, Cambridge, MA, USA
| | | | - Trent Rector
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Robert Steen
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - George M Church
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Sallie W Chisholm
- Department of Civil and Environmental Engineering, MIT, Cambridge, MA, USA
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31
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Takatani N, Omata T. Effects of PII deficiency on expression of the genes involved in ammonium utilization in the cyanobacterium Synechocystis sp. Strain PCC 6803. PLANT & CELL PHYSIOLOGY 2006; 47:679-88. [PMID: 16549396 DOI: 10.1093/pcp/pcj037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The Synechocystis sp. strain PCC 6803 mutant deficient in PII protein (the glnB gene product) was found to express glutamine synthetase activity at levels several times higher than the wild-type strain. There was no significant difference in nitrate reductase activity levels between the two strains, and the nitrite reductase levels were somewhat lower in the mutant than in the wild-type strain. The higher glutamine synthetase activity in the mutant was ascribed to higher expression levels of the glutamine synthetase genes (glnA and glnN), which belong to the regulon controlled by NtcA, a Crp-family transcription regulator. Examination of the effects of PII deficiency on other NtcA-regulated genes revealed that the transcript levels of amt1 (encoding an ammonium permease) and gifB (encoding an inhibitor of glutamine synthetase) were increased, whereas that of gifA (a homolog of gifB, encoding another glutamine synthetase inhibitor) was decreased, with those of nirA, nrtC, icd, sigE (rpoD2-V), nblA and ntcA being unaffected. Unlike the Synechococcus elongatus strain PCC 7942, induction or repression of the NtcA-regulated genes proceeded normally in the PII-deficient mutant upon nitrogen depletion. The altered steady-state expression levels of glnA, glnN, amt1, gifA and gifB in the PII-deficient mutant suggested that Synechocystis sp. strain PCC 6803 has a mechanism for regulation of the subset of the NtcA-regulated genes related directly to ammonium assimilation.
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Affiliation(s)
- Nobuyuki Takatani
- Laboratory of Molecular Plant Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan
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Osanai T, Imamura S, Asayama M, Shirai M, Suzuki I, Murata N, Tanaka K. Nitrogen Induction of Sugar Catabolic Gene Expression in Synechocystis sp. PCC 6803. DNA Res 2006; 13:185-95. [PMID: 17046957 DOI: 10.1093/dnares/dsl010] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nitrogen starvation requires cells to change their transcriptome in order to cope with this essential nutrient limitation. Here, using microarray analysis, we investigated changes in transcript profiles following nitrogen depletion in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Results revealed that genes for sugar catabolic pathways including glycolysis, oxidative pentose phosphate (OPP) pathway, and glycogen catabolism were induced by nitrogen depletion, and activities of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD), two key enzymes of the OPP pathway, were demonstrated to increase under this condition. We recently showed that a group 2 sigma factor SigE, which is under the control of the global nitrogen regulator NtcA, positively regulated these sugar catabolic pathways. However, increases of transcript levels of these sugar catabolic genes under nitrogen starvation were still observed even in a sigE-deficient mutant, indicating the involvement of other regulatory element(s) in addition to SigE. Since these nitrogen activations were abolished in an ntcA mutant, and since these genes were not directly included in the NtcA regulon, we suggested that sugar catabolic genes were induced by nitrogen depletion under complex and redundant regulations including SigE and other unknown factor(s) under the control of NtcA.
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Affiliation(s)
- Takashi Osanai
- Institute of Molecular and Cellular Biosciences, The University of Tokyo 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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Su Z, Olman V, Mao F, Xu Y. Comparative genomics analysis of NtcA regulons in cyanobacteria: regulation of nitrogen assimilation and its coupling to photosynthesis. Nucleic Acids Res 2005; 33:5156-71. [PMID: 16157864 PMCID: PMC1214546 DOI: 10.1093/nar/gki817] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We have developed a new method for prediction of cis-regulatory binding sites and applied it to predicting NtcA regulated genes in cyanobacteria. The algorithm rigorously utilizes concurrence information of multiple binding sites in the upstream region of a gene and that in the upstream regions of its orthologues in related genomes. A probabilistic model was developed for the evaluation of prediction reliability so that the prediction false positive rate could be well controlled. Using this method, we have predicted multiple new members of the NtcA regulons in nine sequenced cyanobacterial genomes, and showed that the false positive rates of the predictions have been reduced on an average of 40-fold compared to the conventional methods. A detailed analysis of the predictions in each genome showed that a significant portion of our predictions are consistent with previously published results about individual genes. Intriguingly, NtcA promoters are found for many genes involved in various stages of photosynthesis. Although photosynthesis is known to be tightly coordinated with nitrogen assimilation, very little is known about the underlying mechanism. We postulate for the fist time that these genes serve as the regulatory points to orchestrate these two important processes in a cyanobacterial cell.
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Affiliation(s)
| | | | | | - Ying Xu
- To whom correspondence should be addressed. Tel: 706 542 9779; Fax: 706 542 9751;
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Muro-Pastor MI, Reyes JC, Florencio FJ. Ammonium assimilation in cyanobacteria. PHOTOSYNTHESIS RESEARCH 2005; 83:135-50. [PMID: 16143848 DOI: 10.1007/s11120-004-2082-7] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2004] [Accepted: 07/17/2004] [Indexed: 05/04/2023]
Abstract
In cyanobacteria, after transport by specific permeases, ammonium is incorporated into carbon skeletons by the sequential action of glutamine synthetase (GS) and glutamate synthase (GOGAT). Two types of GS (GSI and GSIII) and two types of GOGAT (ferredoxin-GOGAT and NADH-GOGAT) have been characterized in cyanobacteria. The carbon skeleton substrate of the GS-GOGAT pathway is 2-oxoglutarate that is synthesized by the isocitrate dehydrogenase (IDH). In order to maintain the C-N balance and the amino acid pools homeostasis, ammonium assimilation is tightly regulated. The key regulatory point is the GS, which is controlled at transcriptional and posttranscriptional levels. The transcription factor NtcA plays a critical role regulating the expression of the GS and the IDH encoding genes. In the unicellular cyanobacterium Synechocystis sp. PCC 6803, NtcA controls also the expression of two small proteins (IF7 and IF17) that inhibit the activity of GS by direct protein-protein interaction. Cyanobacteria perceive nitrogen status by sensing the intracellular concentration of 2-oxoglutarate, a signaling metabolite that is able to modulate allosterically the function of NtcA, in vitro. In vivo, a functional dependence between NtcA and the signal transduction protein PII in controlling NtcA-dependent genes has been also shown.
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Affiliation(s)
- M Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Centro de Investigaciones Isla de la Cartuja, Universidad de Sevilla-CSIC, Av. Américo Vespucio s/n, Seville 41092, Spain. imuro@ ibvf.csic.es
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Forchhammer K. Global carbon/nitrogen control by PII signal transduction in cyanobacteria: from signals to targets. FEMS Microbiol Rev 2004; 28:319-33. [PMID: 15449606 DOI: 10.1016/j.femsre.2003.11.001] [Citation(s) in RCA: 206] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PII signal transduction plays a pervasive role in microbial nitrogen control. Different phylogenetic lineages have developed various signal transduction schemes around the highly conserved core of the signalling system, which consists of the PII proteins. Among all various bacterial PII signalling systems, the one in cyanobacteria is so far unique: in unicellular strains, the mode of covalent modification is by serine phosphorylation and the interpretation of the cellular nitrogen status occurs by measuring the 2-oxoglutarate levels. Recent advances have been the identification of the phospho-PII phosphatase, the resolution of the crystal structure of PII proteins from Synechococcus and Synechocystis strains and the identification of novel functions of PII regulation in cyanobacteria, which highlight the central role of PII signalling for the acclimation to changing carbon-nitrogen regimes.
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Affiliation(s)
- Karl Forchhammer
- Institut für Mikrobiologie und Molekularbiologie, Interdisziplinäres Forschungszentrum der Universität Giessen, Heinrich-Buff-Ring 26-32, Giessen 35392, Germany.
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Asai R, Nakamura C, Ikebukuro K, Karube I, Miyake J. A Bioassay to Detect Contaminant-Induced Messenger RNA Using a Transcriptomic Approach: Detection of RT-PCR-Amplified Single-Stranded DNA Based on the SPR Sensor in Cyanobacteria. ANAL LETT 2003. [DOI: 10.1081/al-120021530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Muro-Pastor MI, Reyes JC, Florencio FJ. Cyanobacteria perceive nitrogen status by sensing intracellular 2-oxoglutarate levels. J Biol Chem 2001; 276:38320-8. [PMID: 11479309 DOI: 10.1074/jbc.m105297200] [Citation(s) in RCA: 232] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The regulatory circuits that control nitrogen metabolism are relatively well known in several bacterial model groups. However, much less is understood about how the nitrogen status of the cell is perceived in vivo. In cyanobacteria, the transcription factor NtcA is required for regulation (activation or repression) of an extensive number of genes involved in nitrogen metabolism. In contrast, how NtcA activity is regulated is largely unknown. Assimilation of ammonium by most microorganisms occurs through the sequential action of two enzymes: glutamine synthetase (GS) and glutamate synthase. Interestingly, regulation of the expression of NtcA-dependent genes in the cyanobacterium Synechocystis sp. PCC 6803 is altered in mutants with modified levels of GS activity. Two types of mutants were analyzed: glnA null mutants that lack GS type I and gif mutants unable to inactivate GS in the presence of ammonium. Changes in the intracellular pools of 19 different amino acids and the keto acid 2-oxoglutarate were recorded in wild-type and mutant strains under different nitrogen conditions. Our data strongly indicate that the nitrogen status in cyanobacteria is perceived as changes in the intracellular 2-oxoglutarate pool.
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Affiliation(s)
- M I Muro-Pastor
- Instituto de Bioquimica Vegetal y Fotosintesis, Universidad de Sevilla-Consejo Superior de Investigaciones Cientificas, Centro de Investigaciones Cientificas Isla de la Cartuja, Avenida Américo Vespucio s/n, Isla de la Cartuja, E-41092 Sevilla, Spain
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Luque I, Zabulon G, Contreras A, Houmard J. Convergence of two global transcriptional regulators on nitrogen induction of the stress-acclimation gene nblA in the cyanobacterium Synechococcus sp. PCC 7942. Mol Microbiol 2001; 41:937-47. [PMID: 11532155 DOI: 10.1046/j.1365-2958.2001.02566.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cyanobacteria respond to environmental stress conditions by degrading their phycobilisomes, the light harvesting complexes for photosynthesis. The expression of nblA, a key gene in this process, is controlled by the response regulator NblR in Synechococcus sp. PCC 7942. Here we show that, under nitrogen stress, nblA is also regulated by NtcA, the global regulator for nitrogen control. NtcA activation of nblA was found to be nitrogen-specific and did not take place under sulphur stress. Transcripts from the two major transcription start points (tsp) for the nblA gene were induced in response to nitrogen and sulphur starvation. The most active one (tspII) required both NblR and NtcA to induce full nblA expression under nitrogen starvation. NblR and NtcA bound in vitro to a DNA fragment from the nblA promoter region, suggesting that, under nitrogen stress, both NblR and NtcA activate the main regulated promoter (PnblA-2) by direct DNA-binding. The structure of PnblA-2 differs from that of the canonical NtcA-activated promoter and it is therefore proposed to represent a novel type of NtcA-dependent promoter. We analysed expression patterns from ntcA and selected NtcA targets in NtcA(-), NblR(-) and wild-type strains, and discuss data suggesting further interrelations between phycobilisome degradation and nitrogen assimilation regulatory pathways.
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Affiliation(s)
- I Luque
- Unité Mixte de Recherche 8543, Centre National de la Recherche Scientifique, Photorégulation et Dynamique des Membranes Végétales, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris cedex 05, France.
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Alfonso M, Perewoska I, Kirilovsky D. Redox control of ntcA gene expression in Synechocystis sp. PCC 6803. Nitrogen availability and electron transport regulate the levels of the NtcA protein. PLANT PHYSIOLOGY 2001; 125:969-981. [PMID: 11161053 PMCID: PMC64897 DOI: 10.1104/pp.125.2.969] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2000] [Revised: 08/16/2000] [Accepted: 10/16/2000] [Indexed: 05/23/2023]
Abstract
In this work we have studied the influence of the cellular redox status in the expression of the Synechocystis sp. PCC 6803 ntcA gene. Two different ntcA transcripts with different 5' ends were detected, depending on the different dark/light or nitrogen availability conditions. Accumulation of a 0.8-kb ntcA message was light and nitrogen dependent, whereas a longer 1.2-kb ntcA transcript was neither light nor nitrogen regulated. NtcA protein levels increased concomitantly with the accumulation of the 0.8-kb ntcA transcript. The light-dependent accumulation of the ntcA gene and the NtcA protein was sensitive to electron transport inhibitors. In addition, Glc-grown Synechocystis sp. cells showed a similar ntcA expression pattern in darkness to that observed under illumination. These data suggested that electron transport, and not light per se may regulate ntcA gene expression. Primer extension analysis, together with gel mobility-shift assays, demonstrated that in vitro, the Synechocystis sp. NtcA protein specifically bound to the putative promoter region from the light/nitrogen-dependent ntcA transcript but not to that from the constitutive 1.2-kb ntcA mRNA. Band-shift experiments carried out in the presence of thiol oxidizing/modifiying agents and different reducing/oxidizing conditions suggested that NtcA binding to its own promoter was under a thiol-dependent redox mechanism. Our results suggest that the cellular redox status plays a central role in the autoregulatory mechanism of the NtcA protein.
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Affiliation(s)
- M Alfonso
- Unité Mixte de Recherche, 8543 Photorégulation et Dynamique des Membranes Végetales, Centre National de la Recherche Scientifique, Ecole Normale Supériéure, 46 rue d'Ulm, 75230 Paris cedex 05, France.
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40
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Affiliation(s)
- A Herrero
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, E-41092 Seville, Spain
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41
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Jiang F, Wisén S, Widersten M, Bergman B, Mannervik B. Examination of the transcription factor NtcA-binding motif by in vitro selection of DNA sequences from a random library. J Mol Biol 2000; 301:783-93. [PMID: 10966785 DOI: 10.1006/jmbi.2000.4000] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A recursive in vitro selection among random DNA sequences was used for analysis of the cyanobacterial transcription factor NtcA-binding motifs. An eight-base palindromic sequence, TGTA-(N(8))-TACA, was found to be the optimal NtcA-binding sequence. The more divergent the binding sequences, compared to this consensus sequence, the lower the NtcA affinity. The second and third bases in each four-nucleotide half of the consensus sequence were crucial for NtcA binding, and they were in general highly conserved. The most frequently occurring sequence in the middle weakly conserved region was similar to that of the NtcA-binding motif of the Anabaena sp. strain PCC 7120 glnA gene, previously known to have high affinity for NtcA. This indicates that the middle sequences were selected for high NtcA affinity. Analysis of natural NtcA-binding motifs showed that these could be classified into two groups based on differences in recognition consensus sequences. It is suggested that NtcA naturally recognizes different DNA-binding motifs, or has differential affinities to these sequences under different physiological conditions.
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Affiliation(s)
- F Jiang
- Department of Biochemistry, Uppsala University, Biomedical Center, Uppsala, S-751 23, Sweden
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Navarro F, Martín-Figueroa E, Florencio FJ. Electron transport controls transcription of the thioredoxin gene (trxA) in the cyanobacterium Synechocystis sp. PCC 6803. PLANT MOLECULAR BIOLOGY 2000; 43:23-32. [PMID: 10949371 DOI: 10.1023/a:1006472018601] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The trxA gene encoding one of the different thioredoxins of the facultative heterotrophic cyanobacterium Synechocystis sp. PCC 6803 is transcribed as a single mRNA of 450 nucleotides. Transcript accumulation is similar in all standard growth conditions but strongly decreases after transferring cell cultures from light to darkness. In steady-state conditions, trxA transcription is reduced at high (150-500 microE m(-2) s(-1)) compared with moderate (10-50 microE m(-2) s(-1)) light intensities. The stability of the trxA transcript was similar at different light intensities, and also in darkness. Photosynthetic electron transport inhibitors, as well as glucose starvation in a mutant strain lacking photosystem II, promote a strong decline in the level of trxA transcript. Primer extension analysis suggests that trxA is transcribed from two proximal promoters containing a -10 TATA box similar to the Escherichia coli consensus promoters. Unlike the trxA mRNA, the amount of thioredoxin protein was not reduced in the dark, neither at high light intensities, indicating that thioredoxin protein is very stable. Our results indicate that the thioredoxin encoded by the trxA gene is likely to be primarily regulated at the transcriptional level, rather than at the protein level, by the electron transport generated photosynthetically or from glucose metabolism.
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Affiliation(s)
- F Navarro
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Centro de Investigaciones Científicas Isla de la Cartuja, Spain
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García-Domínguez M, Reyes JC, Florencio FJ. NtcA represses transcription of gifA and gifB, genes that encode inhibitors of glutamine synthetase type I from Synechocystis sp. PCC 6803. Mol Microbiol 2000; 35:1192-201. [PMID: 10712699 DOI: 10.1046/j.1365-2958.2000.01789.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Synechocystis sp. PCC 6803 glutamine synthetase type I (GS) activity is controlled by direct interaction with two inactivating factors (IF7 and IF17). IF7 and IF17 are homologous polypeptides encoded by the gifA and gifB genes respectively. We investigated the transcriptional regulation of these genes. Expression of both genes is maximum in the presence of ammonium, when GS is inactivated. Nitrogen starvation attenuates the ammonium-mediated induction of gifA and gifB as well as the ammonium-mediated inactivation of GS. Putative binding sites for the transcription factor NtcA were identified at -7.5 and -30.5 bp upstream of gifB and gifA transcription start points respectively. Synechocystis NtcA protein binding to both promoters was demonstrated by gel electrophoresis mobility shift assays. Constitutive high expression levels of both genes were found in a Synechocystis NtcA non-segregated mutant (SNC1), which showed a fourfold reduction in the ntcA expression. These experiments indicate a repressive role for NtcA on the transcription of gifA and gifB genes. Our results demonstrate that NtcA plays a central role in GS regulation in cyanobacteria, stimulating transcription of the glnA gene (GS structural gene) and suppressing transcription of the GS inactivating factor genes gifA and gifB.
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Affiliation(s)
- M García-Domínguez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Centro de Investigaciones Científicas Isla de la Cartuja, C/. Américo Vespucio s/n, 41092 Sevilla, Spain
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Lee HM, Vázquez-Bermúdez MF, de Marsac NT. The global nitrogen regulator NtcA regulates transcription of the signal transducer PII (GlnB) and influences its phosphorylation level in response to nitrogen and carbon supplies in the Cyanobacterium synechococcus sp. strain PCC 7942. J Bacteriol 1999; 181:2697-702. [PMID: 10217756 PMCID: PMC93707 DOI: 10.1128/jb.181.9.2697-2702.1999] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The PII protein is encoded by a unique glnB gene in Synechococcus sp. strain PCC 7942. Its expression has been analyzed in the wild type and in NtcA-null mutant cells grown under different conditions of nitrogen and carbon supply. RNA-DNA hybridization experiments revealed the presence of one transcript species 680 nucleotides long, whatever the nutrient conditions tested. A second transcript species, 620 nucleotides long, absent in the NtcA null mutant, was observed in wild-type cells that were nitrogen starved for 2 h under both high and low CO2 and in the presence of nitrate under a high CO2 concentration. Primer extension analysis indicated that the two transcript species are generated from two tandem promoters, a sigma70 Escherichia coli-type promoter and an NtcA-dependent promoter, located 120 and 53 nucleotides, respectively, from the glnB initiation codon. The NtcA-dependent promoter is up-regulated under the conditions mentioned above, while the sigma70 E. coli-type promoter displays constitutive levels of transcripts in the NtcA null mutant and slightly different levels in the wild-type cells, depending on the nitrogen and carbon supplies. In general, a good correlation between the amounts of the two transcript species and that of the PII protein was observed, as revealed by immunodetection with specific antibodies. The phosphorylation level of PII in the wild type is inversely correlated with nitrogen availability and directly correlated with higher CO2 concentration. This regulation is correspondingly less stringent in the NtcA null mutant cells. In contrast, the dephosphorylation of PII is NtcA independent.
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Affiliation(s)
- H M Lee
- Département de Biochimie et Génétique Moléculaire, Unité de Physiologie Microbienne, Institut Pasteur, 75724 Paris Cedex 15, France
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Pardo MA, Llama MJ, Serra JL. Purification, properties and enhanced expression under nitrogen starvation of the NADP+-isocitrate dehydrogenase from the cyanobacterium Phormidium laminosum. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1431:87-96. [PMID: 10209282 DOI: 10.1016/s0167-4838(99)00052-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitrogen starvation enhances up to 8-fold the cellular level of the NADP+-dependent isocitrate dehydrogenase activity (isocitrate:NADP+ oxidoreductase (decarboxylating), IDH, EC 1.1.1.42) in the thermophilic filamentous non-N2-fixing cyanobacterium Phormidium laminosum. The enzyme was purified 650-fold to electrophoretic homogeneity from nitrogen-starved cells with an activity yield of 25% and a specific activity of 500 U (mg protein)-1. The native enzyme showed a pI of 5.9 and it was a dimer of 107 kDa consisting of two identical subunits of 53 kDa. The activity required the presence of a divalent metal cation as an essential activator, Mn2+ or Mg2+ being the most effective. The optimum temperature for activity was 55 degrees C and the Ea for catalysis was 39.7 kJ mol-1. An optimum pH for activity of 8.5 was found and the calculated pKE1, pKE2 and pKES1 of enzyme ionisation groups were 6.0, 8.9 and 6.3, respectively. Km values of 22, 50 and 24 microM were calculated for d,l-isocitrate, NADP and Mn2+, respectively, in the Mn2+-dependent reaction and 70, 32 and 159 microM for d,l-isocitrate, NADP and Mg2+, respectively, in the Mg2+-dependent reaction. The decarboxylating activity was inhibited by ATP, ADP and by its reaction products 2-oxoglutarate and NADPH2. Polyclonal antibodies raised against the pure IDH were used to assess the presence of the enzyme in cells subjected to nitrogen starvation.
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Affiliation(s)
- M A Pardo
- Enzyme and Cell Technology Group, Department of Biochemistry and Molecular Biology, University of the Basque Country, P.O. Box 644, E-48080, Bilbao, Spain
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Abstract
Growth of enteric bacteria on acetate as the sole source of carbon and energy requires operation of a particular anaplerotic pathway known as the glyoxylate bypass. In this pathway, two specific enzymes, isocitrate lyase and malate synthase, are activated to divert isocitrate from the tricarboxylic acid cycle and prevent the quantitative loss of acetate carbons as carbon dioxide. Bacteria are thus supplied with the metabolic intermediates they need for synthesizing their cellular components. The channeling of isocitrate through the glyoxylate bypass is regulated via the phosphorylation/dephosphorylation of isocitrate dehydrogenase, the enzyme of the tricarboxylic acid cycle which competes for a common substrate with isocitrate lyase. When bacteria are grown on acetate, isocitrate dehydrogenase is phosphorylated and, concomitantly, its activity declines drastically. Conversely, when cells are cultured on a preferred carbon source, such as glucose, the enzyme is dephosphorylated and recovers full activity. Such reversible phosphorylation is mediated by an unusual bifunctional enzyme, isocitrate dehydrogenase kinase/phosphatase, which contains both modifying and demodifying activities on the same polypeptide. The genes coding for malate synthase, isocitrate lyase, and isocitrate dehydrogenase kinase/phosphatase are located in the same operon. Their expression is controlled by a complex dual mechanism that involves several transcriptional repressors and activators. Recent developments have brought new insights into the nature and mode of action of these different regulators. Also, significant advances have been made lately in our understanding of the control of enzyme activity by reversible phosphorylation. In general, analyzing the physiological behavior of bacteria on acetate provides a valuable approach for deciphering at the molecular level the mechanisms of cell adaptation to the environment.
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Affiliation(s)
- A J Cozzone
- Institut de Biologie et Chimie des Protéines, Université de Lyon, France
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47
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Montesinos ML, Muro-Pastor AM, Herrero A, Flores E. Ammonium/methylammonium permeases of a Cyanobacterium. Identification and analysis of three nitrogen-regulated amt genes in synechocystis sp. PCC 6803. J Biol Chem 1998; 273:31463-70. [PMID: 9813059 DOI: 10.1074/jbc.273.47.31463] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ammonium is an important nitrogen source for many microorganisms and plants. Ammonium transporters whose activity can be probed with [14C]methylammonium have been described in several organisms including some cyanobacteria, and amt genes encoding ammonium/methylammonium permeases have been recently identified in yeast, Arabidopsis thaliana, and some bacteria. The unicellular cyanobacterium Synechocystis sp. PCC 6803 exhibited a [14C]methylammonium uptake activity that was inhibited by externally added ammonium. Three putative amt genes that are found in the recently published complete sequence of the chromosome of strain PCC 6803 were inactivated by insertion of antibiotic resistance-encoding gene-cassettes. The corresponding mutant strains were impaired in uptake of [14C]methylammonium. Open reading frame sll0108 (amt1) was responsible for a high affinity uptake activity (Ks for methylammonium, 2.7 microM), whereas open reading frames sll1017 (amt2) and sll0537 (amt3) made minor contributions to uptake at low substrate concentrations. Expression of the three amt genes was higher in nitrogen-starved cells than in cells incubated in the presence of a source of nitrogen (either ammonium or nitrate), but amt1 was expressed at higher levels than the other two amt genes. Transcription of amt1 was found to take place from a promoter bearing the structure of the cyanobacterial promoters activated by the nitrogen control transcription factor, NtcA.
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Affiliation(s)
- M L Montesinos
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, E-41092 Sevilla, Spain
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Bermúdez O, Padilla P, Huitrón C, Flores ME. Influence of carbon and nitrogen source on synthesis of NADP +-isocitrate dehydrogenase, methylmalonyl-coenzyme A mutase, and methylmalonyl-coenzyme A decarboxylase in Saccharopolyspora erythraeaCA340. FEMS Microbiol Lett 1998. [DOI: 10.1111/j.1574-6968.1998.tb13070.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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49
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Reyes F, Gavira M, Castillo F, Moreno-Vivián C. Periplasmic nitrate-reducing system of the phototrophic bacterium Rhodobacter sphaeroides DSM 158: transcriptional and mutational analysis of the napKEFDABC gene cluster. Biochem J 1998; 331 ( Pt 3):897-904. [PMID: 9560320 PMCID: PMC1219433 DOI: 10.1042/bj3310897] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The phototrophic bacterium Rhodobacter sphaeroides DSM 158 is able to reduce nitrate to nitrite by means of a periplasmic nitrate reductase which is induced by nitrate and is not repressed by ammonium or oxygen. Recently, a 6.8 kb PstI DNA fragment carrying the napABC genes coding for this periplasmic nitrate-reducing system was cloned [Reyes, Roldán, Klipp, Castillo and Moreno-Vivián (1996) Mol. Microbiol. 19, 1307-1318]. Further sequence and genetic analyses of the DNA region upstream from the napABC genes reveal the presence of four additional nap genes. All these R. sphaeroides genes seem to be organized into a napKEFDABC transcriptional unit. In addition, a partial open reading frame similar to the Azorhizobium caulinodans yntC gene and the Escherichia coli yjcC and yhjK genes is present upstream from this nap gene cluster. The R. sphaeroides napK gene codes for a putative 6.3 kDa transmembrane protein which is not similar to known proteins and the napE gene codes for a 6.7 kDa transmembrane protein similar to the Thiosphaera pantotropha NapE. The R. sphaeroides napF gene product is a 16.4 kDa protein with four cysteine clusters that probably bind four [4Fe-4S] centres. This iron-sulphur protein shows similarity to the NapF and NapG proteins of E. coli and Haemophilus influenzae. Finally, the napD gene product is a 9.4 kDa soluble protein which is also found in E. coli and T. pantotropha. The 5' end of the nap transcript has been determined by primer extension, and a sigma70-like promoter has been identified upstream from the napK gene. The same transcriptional start site is found for cells growing aerobically or anaerobically with nitrate. Different mutant strains carrying defined polar and non-polar insertions in each nap gene were constructed. Characterization of these mutant strains demonstrates the participation of the nap gene products in the periplasmic nitrate reduction in R. sphaeroides.
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Affiliation(s)
- F Reyes
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, 14071-Córdoba, Spain
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50
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Effect of nitrogen and carbon sources on growth and activities of NAD and NADP dependent isocitrate dehydrogenases of Laccaria bicolor. ACTA ACUST UNITED AC 1998. [DOI: 10.1017/s0953756297005042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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