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Salinas P, Bibak S, Cantos R, Tremiño L, Jerez C, Mata-Balaguer T, Contreras A. Studies on the PII-PipX-NtcA Regulatory Axis of Cyanobacteria Provide Novel Insights into the Advantages and Limitations of Two-Hybrid Systems for Protein Interactions. Int J Mol Sci 2024; 25:5429. [PMID: 38791467 PMCID: PMC11121479 DOI: 10.3390/ijms25105429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 05/11/2024] [Accepted: 05/12/2024] [Indexed: 05/26/2024] Open
Abstract
Yeast two-hybrid approaches, which are based on fusion proteins that must co-localise to the nucleus to reconstitute the transcriptional activity of GAL4, have greatly contributed to our understanding of the nitrogen interaction network of cyanobacteria, the main hubs of which are the trimeric PII and the monomeric PipX regulators. The bacterial two-hybrid system, based on the reconstitution in the E. coli cytoplasm of the adenylate cyclase of Bordetella pertussis, should provide a relatively faster and presumably more physiological assay for cyanobacterial proteins than the yeast system. Here, we used the bacterial two-hybrid system to gain additional insights into the cyanobacterial PipX interaction network while simultaneously assessing the advantages and limitations of the two most popular two-hybrid systems. A comprehensive mutational analysis of PipX and bacterial two-hybrid assays were performed to compare the outcomes between yeast and bacterial systems. We detected interactions that were previously recorded in the yeast two-hybrid system as negative, as well as a "false positive", the self-interaction of PipX, which is rather an indirect interaction that is dependent on PII homologues from the E. coli host, a result confirmed by Western blot analysis with relevant PipX variants. This is, to our knowledge, the first report of the molecular basis of a false positive in the bacterial two-hybrid system.
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Affiliation(s)
| | | | | | | | | | | | - Asunción Contreras
- Departamento. de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, Spain; (P.S.); (S.B.); (R.C.); (L.T.); (C.J.); (T.M.-B.)
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2
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Jerez C, Llop A, Salinas P, Bibak S, Forchhammer K, Contreras A. Analysing the Cyanobacterial PipX Interaction Network Using NanoBiT Complementation in Synechococcus elongatus PCC7942. Int J Mol Sci 2024; 25:4702. [PMID: 38731921 PMCID: PMC11083307 DOI: 10.3390/ijms25094702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 05/13/2024] Open
Abstract
The conserved cyanobacterial protein PipX is part of a complex interaction network with regulators involved in essential processes that include metabolic homeostasis and ribosome assembly. Because PipX interactions depend on the relative levels of their different partners and of the effector molecules binding to them, in vivo studies are required to understand the physiological significance and contribution of environmental factors to the regulation of PipX complexes. Here, we have used the NanoBiT complementation system to analyse the regulation of complex formation in Synechococcus elongatus PCC 7942 between PipX and each of its two best-characterized partners, PII and NtcA. Our results confirm previous in vitro analyses on the regulation of PipX-PII and PipX-NtcA complexes by 2-oxoglutarate and on the regulation of PipX-PII by the ATP/ADP ratio, showing the disruption of PipX-NtcA complexes due to increased levels of ADP-bound PII in Synechococcus elongatus. The demonstration of a positive role of PII on PipX-NtcA complexes during their initial response to nitrogen starvation or the impact of a PipX point mutation on the activity of PipX-PII and PipX-NtcA reporters are further indications of the sensitivity of the system. This study reveals additional regulatory complexities in the PipX interaction network, opening a path for future research on cyanobacteria.
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Affiliation(s)
- Carmen Jerez
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, Spain; (C.J.); (A.L.); (P.S.); (S.B.)
- Interfaculty Institute of Microbiology and Infection Biology, University Tübingen, 72076 Tübingen, Germany;
| | - Antonio Llop
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, Spain; (C.J.); (A.L.); (P.S.); (S.B.)
| | - Paloma Salinas
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, Spain; (C.J.); (A.L.); (P.S.); (S.B.)
| | - Sirine Bibak
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, Spain; (C.J.); (A.L.); (P.S.); (S.B.)
| | - Karl Forchhammer
- Interfaculty Institute of Microbiology and Infection Biology, University Tübingen, 72076 Tübingen, Germany;
| | - Asunción Contreras
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03690 San Vicente del Raspeig, Spain; (C.J.); (A.L.); (P.S.); (S.B.)
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Andreas MP, Giessen TW. The biosynthesis of the odorant 2-methylisoborneol is compartmentalized inside a protein shell. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.23.590730. [PMID: 38712110 PMCID: PMC11071394 DOI: 10.1101/2024.04.23.590730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Terpenoids are the largest class of natural products, found across all domains of life. One of the most abundant bacterial terpenoids is the volatile odorant 2-methylisoborneol (2-MIB), partially responsible for the earthy smell of soil and musty taste of contaminated water. Many bacterial 2-MIB biosynthetic gene clusters were thought to encode a conserved transcription factor, named EshA in the model soil bacterium Streptomyces griseus . Here, we revise the function of EshA, now referred to as Sg Enc, and show that it is a Family 2B encapsulin shell protein. Using cryo-electron microscopy, we find that Sg Enc forms an icosahedral protein shell and encapsulates 2-methylisoborneol synthase (2-MIBS) as a cargo protein. Sg Enc contains a cyclic adenosine monophosphate (cAMP) binding domain (CBD)-fold insertion and a unique metal-binding domain, both displayed on the shell exterior. We show that Sg Enc CBDs do not bind cAMP. We find that 2-MIBS cargo loading is mediated by an N-terminal disordered cargo-loading domain and that 2-MIBS activity and Sg Enc shell structure are not modulated by cAMP. Our work redefines the function of EshA and establishes Family 2B encapsulins as cargo-loaded protein nanocompartments involved in secondary metabolite biosynthesis.
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Rachedi R, Risoul V, Foglino M, Aoudache Y, Lang K, Champ S, Kaplan E, Orelle C, Douzi B, Jault JM, Latifi A. Unravelling HetC as a peptidase-based ABC exporter driving functional cell differentiation in the cyanobacterium Nostoc PCC 7120. Microbiol Spectr 2024; 12:e0405823. [PMID: 38358282 PMCID: PMC10986499 DOI: 10.1128/spectrum.04058-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 01/30/2024] [Indexed: 02/16/2024] Open
Abstract
The export of peptides or proteins is essential for a variety of important functions in bacteria. Among the diverse protein-translocation systems, peptidase-containing ABC transporters (PCAT) are involved in the maturation and export of quorum-sensing or antimicrobial peptides in Gram-positive bacteria and of toxins in Gram-negative organisms. In the multicellular and diazotrophic cyanobacterium Nostoc PCC 7120, the protein HetC is essential for the differentiation of functional heterocysts, which are micro-oxic and non-dividing cells specialized in atmospheric nitrogen fixation. HetC shows similarities to PCAT systems, but whether it actually acts as a peptidase-based exporter remains to be established. In this study, we show that the N-terminal part of HetC, encompassing the peptidase domain, displays a cysteine-type protease activity. The conserved catalytic residues conserved in this family of proteases are essential for the proteolytic activity of HetC and the differentiation of heterocysts. Furthermore, we show that the catalytic residue of the ATPase domain of HetC is also essential for cell differentiation. Interestingly, HetC has a cyclic nucleotide-binding domain at its N-terminus which can bind ppGpp in vitro and which is required for its function in vivo. Our results indicate that HetC is a peculiar PCAT that might be regulated by ppGpp to potentially facilitate the export of a signaling peptide essential for cell differentiation, thereby broadening the scope of PCAT role in Gram-negative bacteria.IMPORTANCEBacteria have a great capacity to adapt to various environmental and physiological conditions; it is widely accepted that their ability to produce extracellular molecules contributes greatly to their fitness. Exported molecules are used for a variety of purposes ranging from communication to adjust cellular physiology, to the production of toxins that bacteria secrete to fight for their ecological niche. They use export machineries for this purpose, the most common of which energize transport by hydrolysis of adenosine triphosphate. Here, we demonstrate that such a mechanism is involved in cell differentiation in the filamentous cyanobacterium Nostoc PCC 7120. The HetC protein belongs to the ATP-binding cassette transporter superfamily and presumably ensures the maturation of a yet unknown substrate during export. These results open interesting perspectives on cellular signaling pathways involving the export of regulatory peptides, which will broaden our knowledge of how these bacteria use two cell types to conciliate photosynthesis and nitrogen fixation.
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Affiliation(s)
- Raphaël Rachedi
- Aix-Marseille Université, CNRS, Laboratoire de Chimie Bactérienne LCB, IMM, Marseille, France
| | - Véronique Risoul
- Aix-Marseille Université, CNRS, Laboratoire de Chimie Bactérienne LCB, IMM, Marseille, France
| | - Maryline Foglino
- Aix-Marseille Université, CNRS, Laboratoire de Chimie Bactérienne LCB, IMM, Marseille, France
| | | | - Kevin Lang
- Microbiologie Moléculaire et Biochimie Structurale, UMR5086 Université de Lyon/CNRS, IBCP, Lyon, France
| | - Stéphanie Champ
- Aix-Marseille Université, CNRS, Laboratoire de Chimie Bactérienne LCB, IMM, Marseille, France
| | - Elise Kaplan
- Microbiologie Moléculaire et Biochimie Structurale, UMR5086 Université de Lyon/CNRS, IBCP, Lyon, France
| | - Cédric Orelle
- Microbiologie Moléculaire et Biochimie Structurale, UMR5086 Université de Lyon/CNRS, IBCP, Lyon, France
| | | | - Jean-Michel Jault
- Microbiologie Moléculaire et Biochimie Structurale, UMR5086 Université de Lyon/CNRS, IBCP, Lyon, France
| | - Amel Latifi
- Aix-Marseille Université, CNRS, Laboratoire de Chimie Bactérienne LCB, IMM, Marseille, France
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Li B, Wang XQ, Li QY, Xu D, Li J, Hou WT, Chen Y, Jiang YL, Zhou CZ. Allosteric regulation of nitrate transporter NRT via the signaling protein PII. Proc Natl Acad Sci U S A 2024; 121:e2318320121. [PMID: 38457518 PMCID: PMC10945777 DOI: 10.1073/pnas.2318320121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Accepted: 01/10/2024] [Indexed: 03/10/2024] Open
Abstract
Coordinated carbon and nitrogen metabolism is crucial for bacteria living in the fluctuating environments. Intracellular carbon and nitrogen homeostasis is maintained by a sophisticated network, in which the widespread signaling protein PII acts as a major regulatory hub. In cyanobacteria, PII was proposed to regulate the nitrate uptake by an ABC (ATP-binding cassette)-type nitrate transporter NrtABCD, in which the nucleotide-binding domain of NrtC is fused with a C-terminal regulatory domain (CRD). Here, we solved three cryoelectron microscopy structures of NrtBCD, bound to nitrate, ATP, and PII, respectively. Structural and biochemical analyses enable us to identify the key residues that form a hydrophobic and a hydrophilic cavity along the substrate translocation channel. The core structure of PII, but not the canonical T-loop, binds to NrtC and stabilizes the CRD, making it visible in the complex structure, narrows the substrate translocation channel in NrtB, and ultimately locks NrtBCD at an inhibited inward-facing conformation. Based on these results and previous reports, we propose a putative transport cycle driven by NrtABCD, which is allosterically inhibited by PII in response to the cellular level of 2-oxoglutarate. Our findings provide a distinct regulatory mechanism of ABC transporter via asymmetrically binding to a signaling protein.
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Affiliation(s)
- Bo Li
- Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei230027, China
| | - Xiao-Qian Wang
- Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei230027, China
| | - Qin-Yao Li
- Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei230027, China
| | - Da Xu
- Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei230027, China
| | - Jing Li
- Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei230027, China
| | - Wen-Tao Hou
- Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei230027, China
| | - Yuxing Chen
- Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei230027, China
| | - Yong-Liang Jiang
- Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei230027, China
| | - Cong-Zhao Zhou
- Division of Life Sciences and Medicine, School of Life Sciences, University of Science and Technology of China, Hefei230027, China
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6
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Han SJ, Jiang YL, You LL, Shen LQ, Wu X, Yang F, Cui N, Kong WW, Sun H, Zhou K, Meng HC, Chen ZP, Chen Y, Zhang Y, Zhou CZ. DNA looping mediates cooperative transcription activation. Nat Struct Mol Biol 2024; 31:293-299. [PMID: 38177666 DOI: 10.1038/s41594-023-01149-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 10/04/2023] [Indexed: 01/06/2024]
Abstract
Transcription factors respond to multilevel stimuli and co-occupy promoter regions of target genes to activate RNA polymerase (RNAP) in a cooperative manner. To decipher the molecular mechanism, here we report two cryo-electron microscopy structures of Anabaena transcription activation complexes (TACs): NtcA-TAC composed of RNAP holoenzyme, promoter and a global activator NtcA, and NtcA-NtcB-TAC comprising an extra context-specific regulator, NtcB. Structural analysis showed that NtcA binding makes the promoter DNA bend by ∼50°, which facilitates RNAP to contact NtcB at the distal upstream NtcB box. The sequential binding of NtcA and NtcB induces looping back of promoter DNA towards RNAP, enabling the assembly of a fully activated TAC bound with two activators. Together with biochemical assays, we propose a 'DNA looping' mechanism of cooperative transcription activation in bacteria.
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Affiliation(s)
- Shu-Jing Han
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China
| | - Yong-Liang Jiang
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China.
| | - Lin-Lin You
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Li-Qiang Shen
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Xiaoxian Wu
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Feng Yang
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China
| | - Ning Cui
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China
| | - Wen-Wen Kong
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China
| | - Hui Sun
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China
| | - Ke Zhou
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China
| | - Hui-Chao Meng
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China
| | - Zhi-Peng Chen
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China
| | - Yuxing Chen
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China
| | - Yu Zhang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
| | - Cong-Zhao Zhou
- School of Life Sciences and Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, China.
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7
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Hidese R, Ohbayashi R, Kato Y, Matsuda M, Tanaka K, Imamura S, Ashida H, Kondo A, Hasunuma T. ppGpp accumulation reduces the expression of the global nitrogen homeostasis-modulating NtcA regulon by affecting 2-oxoglutarate levels. Commun Biol 2023; 6:1285. [PMID: 38145988 PMCID: PMC10749895 DOI: 10.1038/s42003-023-05632-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 11/23/2023] [Indexed: 12/27/2023] Open
Abstract
The cyanobacterium Synechococcus elongatus PCC 7942 accumulates alarmone guanosine tetraphosphate (ppGpp) under stress conditions, such as darkness. A previous study observed that artificial ppGpp accumulation under photosynthetic conditions led to the downregulation of genes involved in the nitrogen assimilation system, which is activated by the global nitrogen regulator NtcA, suggesting that ppGpp regulates NtcA activity. However, the details of this mechanism have not been elucidated. Here, we investigate the metabolic responses associated with ppGpp accumulation by heterologous expression of the ppGpp synthetase RelQ. The pool size of 2-oxoglutarate (2-OG), which activates NtcA, is significantly decreased upon ppGpp accumulation. De novo 13C-labeled CO2 assimilation into the Calvin-Benson-Bassham cycle and glycolytic intermediates continues irrespective of ppGpp accumulation, whereas the labeling of 2-OG is significantly decreased under ppGpp accumulation. The low 2-OG levels in the RelQ overexpression cells could be because of the inhibition of metabolic enzymes, including aconitase, which are responsible for 2-OG biosynthesis. We propose a metabolic rearrangement by ppGpp accumulation, which negatively regulates 2-OG levels to maintain carbon and nitrogen balance.
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Affiliation(s)
- Ryota Hidese
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Ryudo Ohbayashi
- Laboratory for Chemistry and Life Science Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
- Department of Biological Sciences, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Yuichi Kato
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Mami Matsuda
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
| | - Sousuke Imamura
- Laboratory for Chemistry and Life Science Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
- NTT Space Environment and Enegy Laboratories, Nippon Telegraph and Telephone Corporation, 3-9-11 Midori-cho, Musashino-shi, Tokyo, 180-8585, Japan
| | - Hiroki Ashida
- Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada-Ku, Kobe, 657-8501, Japan
| | - Akihiko Kondo
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
- Research Center for Sustainable Resource Science, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan
| | - Tomohisa Hasunuma
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan.
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan.
- Research Center for Sustainable Resource Science, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan.
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8
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Xing WY, Liu J, Zhang CC. HetF defines a transition point from commitment to morphogenesis during heterocyst differentiation in the cyanobacterium Anabaena sp. PCC 7120. Mol Microbiol 2023; 120:740-753. [PMID: 37804047 DOI: 10.1111/mmi.15177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/16/2023] [Accepted: 09/22/2023] [Indexed: 10/08/2023]
Abstract
The filamentous cyanobacterium Anabaena sp. PCC 7120 is able to form heterocysts for nitrogen fixation. Heterocyst differentiation is initiated by combined-nitrogen deprivation, followed by the commitment step during which the developmental process becomes irreversible. Mature heterocysts are terminally differentiated cells unable to divide, and cell division is required for heterocyst differentiation. Previously, we have shown that the HetF protease regulates cell division and heterocyst differentiation by cleaving PatU3, which is an inhibitor for both events. When hetF is required during the developmental program remains unknown. Here, by controlling the timing of hetF expression during heterocyst differentiation, we provide evidence that hetF is required just before the beginning of heterocyst morphogenesis. Consistent with this finding, transcriptome data show that most of the genes known to be involved in the early step (such as hetR and ntcA) or the commitment step (such as hetP and hetZ) of heterocyst development could be expressed in the ΔhetF mutant. In contrast, most of the genes involved in heterocyst morphogenesis and nitrogen fixation remain repressed in the mutant. These results indicated that in the absence of hetF, heterocyst differentiation is able to be initiated and proceeds to the stage just before heterocyst envelope formation.
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Affiliation(s)
- Wei-Yue Xing
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China
| | - Jing Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China
| | - Cheng-Cai Zhang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China
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9
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Giordano M, Goodman CA, Huang F, Raven JA, Ruan Z. A mechanistic study of the influence of nitrogen and energy availability on the NH4+ sensitivity of nitrogen assimilation in Synechococcus. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:5596-5611. [PMID: 35595516 PMCID: PMC9467657 DOI: 10.1093/jxb/erac219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 05/19/2022] [Indexed: 05/23/2023]
Abstract
In most algae, NO3- assimilation is tightly controlled and is often inhibited by the presence of NH4+. In the marine, non-colonial, non-diazotrophic cyanobacterium Synechococcus UTEX 2380, NO3- assimilation is sensitive to NH4+ only when N does not limit growth. We sequenced the genome of Synechococcus UTEX 2380, studied the genetic organization of the nitrate assimilation related (NAR) genes, and investigated expression and kinetics of the main NAR enzymes, under N or light limitation. We found that Synechococcus UTEX 2380 is a β-cyanobacterium with a full complement of N uptake and assimilation genes and NAR regulatory elements. The nitrate reductase of our strain showed biphasic kinetics, previously observed only in freshwater or soil diazotrophic Synechococcus strains. Nitrite reductase and glutamine synthetase showed little response to our growth treatments, and their activity was usually much higher than that of nitrate reductase. NH4+ insensitivity of NAR genes may be associated with the stimulation of the binding of the regulator NtcA to NAR gene promoters by the high 2-oxoglutarate concentrations produced under N limitation. NH4+ sensitivity in energy-limited cells fits with the fact that, under these conditions, the use of NH4+ rather than NO3- decreases N-assimilation cost, whereas it would exacerbate N shortage under N limitation.
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Affiliation(s)
- Mario Giordano
- STU-UNIVPM Joint Algal Research Center, Marine Biology Institute, Shantou University, Shantou, Guangdong 515063, China
- Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, Ancona 60131, Italy
- CMNS-Cell Biology and Molecular Genetics, 2107 Bioscience Research Building, University of Maryland, College Park, MD 20742-4407, USA
- Institute of Microbiology ASCR, Algatech, Trebon, Czech Republic
- National Research Council, Institute of Marine Science, Venezia, Italy
| | - Charles A Goodman
- CMNS-Cell Biology and Molecular Genetics, 2107 Bioscience Research Building, University of Maryland, College Park, MD 20742-4407, USA
| | - Fengying Huang
- STU-UNIVPM Joint Algal Research Center, Marine Biology Institute, Shantou University, Shantou, Guangdong 515063, China
| | - John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5 DA, UK
- Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Ultimo NSW 2007, Australia
- School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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10
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Kramer BJ, Jankowiak JG, Nanjappa D, Harke MJ, Gobler CJ. Nitrogen and phosphorus significantly alter growth, nitrogen fixation, anatoxin-a content, and the transcriptome of the bloom-forming cyanobacterium, Dolichospermum. Front Microbiol 2022; 13:955032. [PMID: 36160233 PMCID: PMC9490380 DOI: 10.3389/fmicb.2022.955032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/19/2022] [Indexed: 11/27/2022] Open
Abstract
While freshwater cyanobacteria are traditionally thought to be limited by the availability of phosphorus (P), fixed nitrogen (N) supply can promote the growth and/or toxin production of some genera. This study characterizes how growth on N2 (control), nitrate (NO3 -), ammonium (NH4 +), and urea as well as P limitation altered the growth, toxin production, N2 fixation, and gene expression of an anatoxin-a (ATX-A) - producing strain of Dolichospermum sp. 54. The transcriptomes of fixed N and P-limited cultures differed significantly from those of fixed N-deplete, P-replete (control) cultures, while the transcriptomes of P-replete cultures amended with either NH4 + or NO3 - were not significantly different relative to those of the control. Growth rates of Dolichospermum (sp. 54) were significantly higher when grown on fixed N relative to without fixed N; growth on NH4 + was also significantly greater than growth on NO3 -. NH4 + and urea significantly lowered N2 fixation and nifD gene transcript abundance relative to the control while cultures amended with NO3 - exhibited N2 fixation and nifD gene transcript abundance that was not different from the control. Cultures grown on NH4 + exhibited the lowest ATX-A content per cell and lower transcript abundance of genes associated ATX-A synthesis (ana), while the abundance of transcripts of several ana genes were highest under fixed N and P - limited conditions. The significant negative correlation between growth rate and cellular anatoxin quota as well as the significantly higher number of transcripts of ana genes in cultures deprived of fixed N and P relative to P-replete cultures amended with NH4 + suggests ATX-A was being actively synthesized under P limitation. Collectively, these findings indicate that management strategies that do not regulate fixed N loading will leave eutrophic water bodies vulnerable to more intense and toxic (due to increased biomass) blooms of Dolichospermum.
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Affiliation(s)
- Benjamin J. Kramer
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY, United States
| | | | - Deepak Nanjappa
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY, United States
| | - Matthew J. Harke
- Gloucester Marine Genomics Institute, Gloucester, MA, United States
| | - Christopher J. Gobler
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY, United States
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11
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Abstract
Heterocyst differentiation that occurs in some filamentous cyanobacteria, such as Anabaena sp. PCC 7120, provides a unique model for prokaryotic developmental biology. Heterocyst cells are formed in response to combined-nitrogen deprivation and possess a microoxic environment suitable for nitrogen fixation following extensive morphological and physiological reorganization. A filament of Anabaena is a true multicellular organism, as nitrogen and carbon sources are exchanged among different cells and cell types through septal junctions to ensure filament growth. Because heterocysts are terminally differentiated cells and unable to divide, their activity is an altruistic behavior dedicated to providing fixed nitrogen for neighboring vegetative cells. Heterocyst development is also a process of one-dimensional pattern formation, as heterocysts are semiregularly intercalated among vegetative cells. Morphogens form gradients along the filament and interact with each other in a fashion that fits well into the Turing model, a mathematical framework to explain biological pattern formation. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Xiaoli Zeng
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China; ,
| | - Cheng-Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China; , .,Institut WUT-AMU, Aix-Marseille Université and Wuhan University of Technology, Wuhan, Hubei, China.,Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
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12
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Kallio P, Kugler A, Pyytövaara S, Stensjö K, Allahverdiyeva Y, Gao X, Lindblad P, Lindberg P. Photoautotrophic production of renewable ethylene by engineered cyanobacteria: Steering the cell metabolism towards biotechnological use. PHYSIOLOGIA PLANTARUM 2021; 173:579-590. [PMID: 33864400 DOI: 10.1111/ppl.13430] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 04/05/2021] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
Ethylene is a volatile hydrocarbon with a massive global market in the plastic industry. The ethylene now used for commercial applications is produced exclusively from nonrenewable petroleum sources, while competitive biotechnological production systems do not yet exist. This review focuses on the currently developed photoautotrophic bioproduction strategies that enable direct solar-driven conversion of CO2 into ethylene, based on the use of genetically engineered photosynthetic cyanobacteria expressing heterologous ethylene forming enzyme (EFE) from Pseudomonas syringae. The emphasis is on the different engineering strategies to express EFE and to direct the cellular carbon flux towards the primary metabolite 2-oxoglutarate, highlighting associated metabolic constraints, and technical considerations on cultivation strategies and conditional parameters. While the research field has progressed towards more robust strains with better production profiles, and deeper understanding of the associated metabolic limitations, it is clear that there is room for significant improvement to reach industrial relevance. At the same time, existing information and the development of synthetic biology tools for engineering cyanobacteria open new possibilities for improving the prospects for the sustainable production of renewable ethylene.
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Affiliation(s)
- Pauli Kallio
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, Finland
| | - Amit Kugler
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden
| | - Samuli Pyytövaara
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, Finland
| | - Karin Stensjö
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden
| | - Yagut Allahverdiyeva
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, Finland
| | - Xiang Gao
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, China
| | - Peter Lindblad
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden
| | - Pia Lindberg
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden
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13
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Matilla MA, Velando F, Martín-Mora D, Monteagudo-Cascales E, Krell T. A catalogue of signal molecules that interact with sensor kinases, chemoreceptors and transcriptional regulators. FEMS Microbiol Rev 2021; 46:6356564. [PMID: 34424339 DOI: 10.1093/femsre/fuab043] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 08/10/2021] [Indexed: 12/12/2022] Open
Abstract
Bacteria have evolved many different signal transduction systems that sense signals and generate a variety of responses. Generally, most abundant are transcriptional regulators, sensor histidine kinases and chemoreceptors. Typically, these systems recognize their signal molecules with dedicated ligand-binding domains (LBDs), which, in turn, generate a molecular stimulus that modulates the activity of the output module. There are an enormous number of different LBDs that recognize a similarly diverse set of signals. To give a global perspective of the signals that interact with transcriptional regulators, sensor kinases and chemoreceptors, we manually retrieved information on the protein-ligand interaction from about 1,200 publications and 3D structures. The resulting 811 proteins were classified according to the Pfam family into 127 groups. These data permit a delineation of the signal profiles of individual LBD families as well as distinguishing between families that recognize signals in a promiscuous manner and those that possess a well-defined ligand range. A major bottleneck in the field is the fact that the signal input of many signaling systems is unknown. The signal repertoire reported here will help the scientific community design experimental strategies to identify the signaling molecules for uncharacterised sensor proteins.
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Affiliation(s)
- Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Félix Velando
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - David Martín-Mora
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Elizabet Monteagudo-Cascales
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
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14
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Wang L, Niu TC, Valladares A, Lin GM, Zhang JY, Herrero A, Chen WL, Zhang CC. The developmental regulator PatD modulates assembly of the cell-division protein FtsZ in the cyanobacterium Anabaena sp. PCC 7120. Environ Microbiol 2021; 23:4823-4837. [PMID: 34296514 DOI: 10.1111/1462-2920.15682] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/07/2021] [Accepted: 07/19/2021] [Indexed: 01/02/2023]
Abstract
FtsZ is a tubulin-like GTPase that polymerizes to initiate the process of cell division in bacteria. Heterocysts are terminally differentiated cells of filamentous cyanobacteria that have lost the capacity for cell division and in which the ftsZ gene is downregulated. However, mechanisms of FtsZ regulation during heterocyst differentiation have been scarcely investigated. The patD gene is NtcA dependent and involved in the optimization of heterocyst frequency in Anabaena sp. PCC 7120. Here, we report that the inactivation of patD caused the formation of multiple FtsZ-rings in vegetative cells, cell enlargement, and the retention of peptidoglycan synthesis activity in heterocysts, whereas its ectopic expression resulted in aberrant FtsZ polymerization and cell division. PatD interacted with FtsZ, increased FtsZ precipitation in sedimentation assays, and promoted the formation of thick straight FtsZ bundles that differ from the toroidal aggregates formed by FtsZ alone. These results suggest that in the differentiating heterocysts, PatD interferes with the assembly of FtsZ. We propose that in Anabaena FtsZ is a bifunctional protein involved in both vegetative cell division and regulation of heterocyst differentiation. In the differentiating cells PatD-FtsZ interactions appear to set an FtsZ activity that is insufficient for cell division but optimal to foster differentiation.
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Affiliation(s)
- Li Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Tian-Cai Niu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China
| | - Ana Valladares
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Seville, Spain
| | - Gui-Ming Lin
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China
| | - Ju-Yuan Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China
| | - Antonia Herrero
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Seville, Spain
| | - Wen-Li Chen
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Cheng-Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.,Institut AMU-WUT, Aix-Marseille University and Wuhan University of Technology, Wuhan, Hubei, 430070, China
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15
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Chen Z, Shang JL, Hou S, Li T, Li Q, Yang YW, Hess WR, Qiu BS. Genomic and transcriptomic insights into the habitat adaptation of the diazotrophic paddy-field cyanobacterium Nostoc sphaeroides. Environ Microbiol 2021; 23:5802-5822. [PMID: 33848055 DOI: 10.1111/1462-2920.15521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 03/25/2021] [Accepted: 04/08/2021] [Indexed: 12/13/2022]
Abstract
Nitrogen-fixing cyanobacteria are common in paddy fields, one of the most productive wetland ecosystems. Here, we present the complete genome of Nostoc sphaeroides, a paddy-field diazotroph used for food and medicine for more than 1700 years and deciphered the transcriptional regulation during the developmental transition from hormogonia to vegetative filaments with heterocysts. The genome of N. sphaeroides consists of one circular chromosome (6.48 Mb), one of the largest ever reported megaplasmids (2.34 Mb), and seven plasmids. Multiple gene families involved in the adaption to high solar radiation and water fluctuation conditions were found expanded, while genes involved in anoxic adaptation and phosphonate utilization are located on the megaplasmid, suggesting its indispensable role in environmental adaptation. Distinct gene expression patterns were observed during the light-intensity-regulated transition from hormogonia to vegetative filaments, specifically, genes encoding proteins involved in photosynthetic light reaction, carbon fixation, nitrogen metabolism and heterocyst differentiation were significantly upregulated, whereas genes related to cell motility were down-regulated. Our results provide genomic and transcriptomic insights into the adaptation of a filamentous nitrogen-fixing cyanobacterium to the highly dynamic paddy-field habitat, suggesting N. sphaeroides as an excellent system to understand the transition from aquatic to terrestrial habitats and to support sustainable rice production.
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Affiliation(s)
- Zhen Chen
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China.,Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, 435002, China
| | - Jin-Long Shang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Shengwei Hou
- Department of Biological Sciences, University of Southern California, CA, Los Angeles, 90089, USA
| | - Tao Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Science, Wuhan, Hubei, 430072, China
| | - Qi Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Science, Wuhan, Hubei, 430072, China
| | - Yi-Wen Yang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Wolfgang R Hess
- Genetics and Experimental Bioinformatics, Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, 79104, Germany
| | - Bao-Sheng Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
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16
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Gunawardana D. An in silico Study of Two Transcription Factors Controlling Diazotrophic Fates of the Azolla Major Cyanobiont Trichormus azollae. Bioinform Biol Insights 2020; 14:1177932220977490. [PMID: 33402818 PMCID: PMC7747107 DOI: 10.1177/1177932220977490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 11/01/2020] [Indexed: 11/17/2022] Open
Abstract
The cyanobiont Trichormus azollae lives symbiotically within fronds of the genus Azolla, and assimilates atmospheric nitrogen upon N-limitation, which earmarks this symbiosis to be a valuable biofertilizer in rice cultivation, among many other benefits that also include carbon sequestration. Therefore, studying the regulation of nitrogen fixation in Trichormus azollae is of great importance and benefit, especially the two topmost rungs of regulation, the NtcA and HetR transcription factors that are able to regulate the expression of myriads of downstream genes. Bioinformatics tools were used to zoom in on the NtcA and HetR transcription factors from Trichormus azollae to elaborate on what makes this particular cyanobiont different from other symbiotic as well as more distinct counterparts, in their commitment to nitrogen fixation. The utility of Azolla plants in tropical agriculture in particular merits the "top down N-regulation" by cyanobiont as a significant niche area of study, to make sense of superior N-fixing capabilities. The Trichormus azollae NtcA sequence was found as a phylogenetic outlier to horizontally infecting cyanobionts, which points to a distinct identity compared to symbiotic counterparts. There were borderline (60%-70%) levels of acceptable bootstrap support for the phylogenetic position of the Azolla cyanobiont's NtcA protein compared to other cyanobionts. Furthermore, the NtcA global nitrogen regulator in the Azolla cyanobiont has an extra cysteine at position 128, in addition to two other more conspicuous cysteines (positions, 157 and 164). A simulated homology model of the NtcA protein from Trichormus azollae, points to a single unique cysteine (Cysteine-128) as a key residue at the center of a lengthy C-helix, which forms a coiled-coil interface, through likely disulfide bond formation. Three cysteine (Cysteines: 128, 157, 164) architecture is exclusively found in Trichormus azollae and is absent in other cyanobacteria. A separate proline to alanine mutation in position 97-again exclusive to Trichormus azollae-appears to influence the flexibility of effector binding domain (EBD) to 2-oxoglutarate. The Trichormus azollae HetR sequence was found outside of horizontally-infecting cyanobiont sequences that formed a common clade, with the exception of the cyanobiont from the genus Cycas that formed one line of descent with the Trichormus azollae counterpart. Five (out of 6) serines predicted to be phosphorylated in the Trichormus azollae HetR sequence, are conserved in the Nostoc punctiforme counterpart, showcasing that phosphorylation is likley conserved in both vertically-transmitted and horizontally-acquired cyanobionts. A key Serine-127, within a conserved motif TSLTS, although conserved in heterocystous subsection IV and V cyanobacteria, are mutated in subsection III cyanobacteria that form trichomes but are unable to form heterocysts. I conclude that the NtcA protein from Trichormus azollae to be strategically divergent at specific amino acids that gives it an advantage in function as a 2-oxoglutarate-mediated transcription factor. The Trichormus azollae HetR transcription factor appears to possess parallel functionality to horizontally acquired counterparts. Especially Cysteine-128 in the NtcA transcription factor of the Azolla cyanobiont is an interesting proposition for future structure-function studies.
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17
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Inactivation of Three RG(S/T)GR Pentapeptide-Containing Negative Regulators of HetR Results in Lethal Differentiation of Anabaena PCC 7120. Life (Basel) 2020; 10:life10120326. [PMID: 33291589 PMCID: PMC7761841 DOI: 10.3390/life10120326] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 11/27/2020] [Accepted: 12/01/2020] [Indexed: 12/19/2022] Open
Abstract
The filamentous cyanobacterium Anabaena sp. PCC 7120 produces, during the differentiation of heterocysts, a short peptide PatS and a protein HetN, both containing an RGSGR pentapeptide essential for activity. Both act on the master regulator HetR to guide heterocyst pattern formation by controlling the binding of HetR to DNA and its turnover. A third small protein, PatX, with an RG(S/T)GR motif is present in all HetR-containing cyanobacteria. In a nitrogen-depleted medium, inactivation of patX does not produce a discernible change in phenotype, but its overexpression blocks heterocyst formation. Mutational analysis revealed that PatX is not required for normal intercellular signaling, but it nonetheless is required when PatS is absent to prevent rapid ectopic differentiation. Deprivation of all three negative regulators—PatS, PatX, and HetN—resulted in synchronous differentiation. However, in a nitrogen-containing medium, such deprivation leads to extensive fragmentation, cell lysis, and aberrant differentiation, while either PatX or PatS as the sole HetR regulator can establish and maintain a semiregular heterocyst pattern. These results suggest that tight control over HetR by PatS and PatX is needed to sustain vegetative growth and regulated development. The mutational analysis has been interpreted in light of the opposing roles of negative regulators of HetR and the positive regulator HetL.
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18
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Brandenburg F, Klähn S. Small but Smart: On the Diverse Role of Small Proteins in the Regulation of Cyanobacterial Metabolism. Life (Basel) 2020; 10:E322. [PMID: 33271798 PMCID: PMC7760959 DOI: 10.3390/life10120322] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/25/2020] [Accepted: 11/26/2020] [Indexed: 12/17/2022] Open
Abstract
Over the past few decades, bioengineered cyanobacteria have become a major focus of research for the production of energy carriers and high value chemical compounds. Besides improvements in cultivation routines and reactor technology, the integral understanding of the regulation of metabolic fluxes is the key to designing production strains that are able to compete with established industrial processes. In cyanobacteria, many enzymes and metabolic pathways are regulated differently compared to other bacteria. For instance, while glutamine synthetase in proteobacteria is mainly regulated by covalent enzyme modifications, the same enzyme in cyanobacteria is controlled by the interaction with unique small proteins. Other prominent examples, such as the small protein CP12 which controls the Calvin-Benson cycle, indicate that the regulation of enzymes and/or pathways via the attachment of small proteins might be a widespread mechanism in cyanobacteria. Accordingly, this review highlights the diverse role of small proteins in the control of cyanobacterial metabolism, focusing on well-studied examples as well as those most recently described. Moreover, it will discuss their potential to implement metabolic engineering strategies in order to make cyanobacteria more definable for biotechnological applications.
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Affiliation(s)
| | - Stephan Klähn
- Helmholtz Centre for Environmental Research—UFZ, 04318 Leipzig, Germany;
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19
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Rachedi R, Foglino M, Latifi A. Stress Signaling in Cyanobacteria: A Mechanistic Overview. Life (Basel) 2020; 10:life10120312. [PMID: 33256109 PMCID: PMC7760821 DOI: 10.3390/life10120312] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/22/2020] [Accepted: 11/25/2020] [Indexed: 12/22/2022] Open
Abstract
Cyanobacteria are highly diverse, widely distributed photosynthetic bacteria inhabiting various environments ranging from deserts to the cryosphere. Throughout this range of niches, they have to cope with various stresses and kinds of deprivation which threaten their growth and viability. In order to adapt to these stresses and survive, they have developed several global adaptive responses which modulate the patterns of gene expression and the cellular functions at work. Sigma factors, two-component systems, transcriptional regulators and small regulatory RNAs acting either separately or collectively, for example, induce appropriate cyanobacterial stress responses. The aim of this review is to summarize our current knowledge about the diversity of the sensors and regulators involved in the perception and transduction of light, oxidative and thermal stresses, and nutrient starvation responses. The studies discussed here point to the fact that various stresses affecting the photosynthetic capacity are transduced by common mechanisms.
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20
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Rapid Transcriptional Reprogramming Triggered by Alteration of the Carbon/Nitrogen Balance Has an Impact on Energy Metabolism in Nostoc sp. PCC 7120. Life (Basel) 2020; 10:life10110297. [PMID: 33233741 PMCID: PMC7699953 DOI: 10.3390/life10110297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/12/2020] [Accepted: 11/18/2020] [Indexed: 12/12/2022] Open
Abstract
Nostoc (Anabaena) sp. PCC 7120 is a filamentous cyanobacterial species that fixes N2 to nitrogenous compounds using specialised heterocyst cells. Changes in the intracellular ratio of carbon to nitrogen (C/N balance) is known to trigger major transcriptional reprogramming of the cell, including initiating the differentiation of vegetative cells to heterocysts. Substantial transcriptional analysis has been performed on Nostoc sp. PCC 7120 during N stepdown (low to high C/N), but not during C stepdown (high to low C/N). In the current study, we shifted the metabolic balance of Nostoc sp. PCC 7120 cultures grown at 3% CO2 by introducing them to atmospheric conditions containing 0.04% CO2 for 1 h, after which the changes in gene expression were measured using RNAseq transcriptomics. This analysis revealed strong upregulation of carbon uptake, while nitrogen uptake and metabolism and early stages of heterocyst development were downregulated in response to the shift to low CO2. Furthermore, gene expression changes revealed a decrease in photosynthetic electron transport and increased photoprotection and reactive oxygen metabolism, as well a decrease in iron uptake and metabolism. Differential gene expression was largely attributed to change in the abundances of the metabolites 2-phosphoglycolate and 2-oxoglutarate, which signal a rapid shift from fluent photoassimilation to glycolytic metabolism of carbon after transition to low CO2. This work shows that the C/N balance in Nostoc sp. PCC 7120 rapidly adjusts the metabolic strategy through transcriptional reprogramming, enabling survival in the fluctuating environment.
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21
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Understanding the Differences in the Growth and Toxin Production of Anatoxin-Producing Cuspidothrix issatschenkoi Cultured with Inorganic and Organic N Sources from a New Perspective: Carbon/Nitrogen Metabolic Balance. Toxins (Basel) 2020; 12:toxins12110724. [PMID: 33228063 PMCID: PMC7699347 DOI: 10.3390/toxins12110724] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/14/2020] [Accepted: 11/17/2020] [Indexed: 11/22/2022] Open
Abstract
Cyanotoxins are the underlying cause of the threat that globally pervasive Cyanobacteria Harmful algal blooms (CyanoHABs) pose to humans. Major attention has been focused on the cyanobacterial hepatotoxin microcystins (MCs); however, there is a dearth of studies on cyanobacterial neurotoxin anatoxins. In this study, we explored how an anatoxin-producing Cuspidothrix issatschenkoi strain responded to culture with inorganic and organic nitrogen sources in terms of growth and anatoxins production. The results of our study revealed that ʟ- alanine could greatly boost cell growth, and was associated with the highest cell productivity, while urea significantly stimulated anatoxin production with the maximum anatoxin yield reaching 25.86 μg/mg dry weight, which was 1.56-fold higher than that in the control group (BG11). To further understand whether the carbon/nitrogen balance in C. issatschenkoi would affect anatoxin production, we explored growth and toxin production in response to different carbon/nitrogen ratios (C/N). Anatoxin production was mildly promoted when the C/N ratio was within low range, and significantly inhibited when the C/N ratio was within high range, showing approximately a three-fold difference. Furthermore, the transcriptional profile revealed that anaC gene expression was significantly up-regulated over 2–24 h when the C/N ratio was increased, and was significantly down-regulated after 96 h. Overall, our results further enriched the evidence that urea can stimulate cyanotoxin production, and ʟ-alanine could boost C. issatschenkoi proliferation, thus providing information for better management of aquatic systems. Moreover, by focusing on the intracellular C/N metabolic balance, this study explained the anatoxin production dynamics in C. issatschenkoi in response to different N sources.
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22
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Prabhakant A, Panigrahi A, Krishnan M. Allosteric Response of DNA Recognition Helices of Catabolite Activator Protein to cAMP and DNA Binding. J Chem Inf Model 2020; 60:6366-6376. [PMID: 33108170 DOI: 10.1021/acs.jcim.0c00617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The homodimeric catabolite activator protein (CAP) regulates the transcription of several bacterial genes based on the cellular concentration of cyclic adenosine monophosphate (cAMP). The binding of cAMP to CAP triggers allosteric communication between the cAMP binding domains (CBD) and DNA binding domains (DBD) of CAP, which entails repositioning of DNA recognition helices (F-helices) in the DBD to dock favorably to the target DNA. Despite considerable progress, much remains to be understood about the mechanistic details of DNA recognition by CAP and about the map of allosteric pathways involved in CAP-mediated gene transcription. The present study uses molecular dynamics and umbrella sampling simulations to investigate the mechanism of cAMP- and DNA-induced changes in the conformation and energetics of F-helices observed during the allosteric regulation of CAP by cAMP and the subsequent binding to the DNA promoter region. Using novel collective variables, the free energy profiles associated with the orientation and dynamics of F-helices in the unliganded, cAMP-bound, and cAMP-DNA-bound states of CAP are calculated and compared. The binding-induced alterations in the resultant free energy profiles reveal important flexibility constraints imposed on DBD upon cAMP and DNA binding. A comprehensive analysis of residue-wise interaction maps reveals potential allosteric pathways between CBD and DBD that facilitate the allosteric transduction of regulatory signals in CAP. The revelation that the predicted allosteric pathways crisscross the intersubunit interface offers important clues on the microscopic origin of the intersubunit cooperativity and dimer stability of CAP.
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Affiliation(s)
- Akshay Prabhakant
- Center for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology, Gachibowli, Hyderabad, Telangana 500032, India
| | - Abhinandan Panigrahi
- Center for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology, Gachibowli, Hyderabad, Telangana 500032, India
| | - Marimuthu Krishnan
- Center for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology, Gachibowli, Hyderabad, Telangana 500032, India
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Labella JI, Cantos R, Salinas P, Espinosa J, Contreras A. Distinctive Features of PipX, a Unique Signaling Protein of Cyanobacteria. Life (Basel) 2020; 10:life10060079. [PMID: 32481703 PMCID: PMC7344720 DOI: 10.3390/life10060079] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 05/23/2020] [Accepted: 05/26/2020] [Indexed: 12/20/2022] Open
Abstract
PipX is a unique cyanobacterial protein identified by its ability to bind to PII and NtcA, two key regulators involved in the integration of signals of the nitrogen/carbon and energy status, with a tremendous impact on nitrogen assimilation and gene expression in cyanobacteria. PipX provides a mechanistic link between PII, the most widely distributed signaling protein, and NtcA, a global transcriptional regulator of cyanobacteria. PII, required for cell survival unless PipX is inactivated or down-regulated, functions by protein–protein interactions with transcriptional regulators, transporters, and enzymes. In addition, PipX appears to be involved in a wider signaling network, supported by the following observations: (i) PII–PipX complexes interact with PlmA, an as yet poorly characterized transcriptional regulator also restricted to cyanobacteria; (ii) the pipX gene is functionally connected with pipY, a gene encoding a universally conserved pyridoxal phosphate binding protein (PLPBP) involved in vitamin B6 and amino acid homeostasis, whose loss-of-function mutations cause B6-dependent epilepsy in humans, and (iii) pipX is part of a relatively robust, six-node synteny network that includes pipY and four additional genes that might also be functionally connected with pipX. In this overview, we propose that the study of the protein–protein interaction and synteny networks involving PipX would contribute to understanding the peculiarities and idiosyncrasy of signaling pathways that are conserved in cyanobacteria.
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Ganesh I, Gwon DA, Lee JW. Gas-Sensing Transcriptional Regulators. Biotechnol J 2020; 15:e1900345. [PMID: 32362055 DOI: 10.1002/biot.201900345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 04/08/2020] [Indexed: 11/10/2022]
Abstract
Gas molecules are ubiquitous in the environment and are used as nutrient and energy sources for living organisms. Many organisms, therefore, have developed gas-sensing systems to respond efficiently to changes in the atmospheric environment. In microorganisms and plants, two-component systems (TCSs) and transcription factors (TFs) are two primary mechanisms to sense gas molecules. In this review, gas-sensing transcriptional regulators, TCSs, and TFs, focusing on protein structures, mechanisms of gas molecule interaction, DNA binding regions of transcriptional regulators, signal transduction mechanisms, and gene expression regulation are discussed. At first, transcriptional regulators that directly sense gas molecules with the help of a prosthetic group is described and then gas-sensing systems that indirectly recognize the presence of gas molecules is explained. Overall, this review provides a comprehensive understanding of gas-sensing transcriptional regulators in microorganisms and plants, and proposes a future perspective on the use of gas-sensing transcriptional regulators.
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Affiliation(s)
- Irisappan Ganesh
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Da-Ae Gwon
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Jeong Wook Lee
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea.,School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
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25
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Walter J, Leganés F, Aro EM, Gollan PJ. The small Ca 2+-binding protein CSE links Ca 2+ signalling with nitrogen metabolism and filament integrity in Anabaena sp. PCC 7120. BMC Microbiol 2020; 20:57. [PMID: 32160863 PMCID: PMC7065334 DOI: 10.1186/s12866-020-01735-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 02/24/2020] [Indexed: 02/02/2023] Open
Abstract
Background Filamentous cyanobacteria represent model organisms for investigating multicellularity. For many species, nitrogen-fixing heterocysts are formed from photosynthetic vegetative cells under nitrogen limitation. Intracellular Ca2+ has been implicated in the highly regulated process of heterocyst differentiation but its role remains unclear. Ca2+ is known to operate more broadly in metabolic signalling in cyanobacteria, although the signalling mechanisms are virtually unknown. A Ca2+-binding protein called the Ca2+ Sensor EF-hand (CSE) is found almost exclusively in filamentous cyanobacteria. Expression of asr1131 encoding the CSE protein in Anabaena sp. PCC 7120 was strongly induced by low CO2 conditions, and rapidly downregulated during nitrogen step-down. A previous study suggests a role for CSE and Ca2+ in regulation of photosynthetic activity in response to changes in carbon and nitrogen availability. Results In the current study, a mutant Anabaena sp. PCC 7120 strain lacking asr1131 (Δcse) was highly prone to filament fragmentation, leading to a striking phenotype of very short filaments and poor growth under nitrogen-depleted conditions. Transcriptomics analysis under nitrogen-replete conditions revealed that genes involved in heterocyst differentiation and function were downregulated in Δcse, while heterocyst inhibitors were upregulated, compared to the wild-type. Conclusions These results indicate that CSE is required for filament integrity and for proper differentiation and function of heterocysts upon changes in the cellular carbon/nitrogen balance. A role for CSE in transmitting Ca2+ signals during the first response to changes in metabolic homeostasis is discussed.
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Affiliation(s)
- Julia Walter
- Department of Biochemistry, Molecular Plant Biology, University of Turku, Tykistökatu 6A, 6. krs, 20520, Turku, Finland.,Present address: Department of Plant Sciences, Environmental Plant Physiology, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Francisco Leganés
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Calle Darwin 2, 28049, Madrid, Spain
| | - Eva-Mari Aro
- Department of Biochemistry, Molecular Plant Biology, University of Turku, Tykistökatu 6A, 6. krs, 20520, Turku, Finland
| | - Peter J Gollan
- Department of Biochemistry, Molecular Plant Biology, University of Turku, Tykistökatu 6A, 6. krs, 20520, Turku, Finland.
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He P, Cai X, Chen K, Fu X. Identification of small RNAs involved in nitrogen fixation in Anabaena sp. PCC 7120 based on RNA-seq under steady state conditions. ANN MICROBIOL 2020. [DOI: 10.1186/s13213-020-01557-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Abstract
Purpose
Anabaena sp. PCC7120 is a genetically tractable model organism for nitrogen fixation and photosynthesis research. The importance of small regulatory RNAs (sRNAs) as mediators of a number of cellular processes in bacteria has begun to be recognized. Bacterial sRNA binds to target genes through base pairing, and play a regulatory role. Many studies have shown that bacterial sRNA can regulate cell stress response, carbon and nitrogen fixation, and so on. However, little is known about sRNAs in Anabaena sp. PCC 7120 regarded to nitrogen fixation under later steady state.
Methods
To provide a comprehensive study of sRNAs in this model organism, the sRNA (< 200 nt) extracted from Anabaena sp. PCC 7120 under nitrogen step-down treatment of 12 days, together with the sRNA from the control, was analyzed using deep RNA sequencing. Possible target genes regulated by all identified putative sRNAs were predicted by IntaRNA and further analyzed for functional categorizations for biological pathways.
Result
Totally, 14,132 transcripts were produced from the de novo assembly. Among them, transcripts that are located either in the intergenic region or antisense strand were kept, which resulted in 1219 sRNA candidates, for further analysis. RPKM-based differential expression analysis showed that 418 sRNAs were significantly differentially expressed between the samples from control (nitrogen addition, N+) and nitrogen depletion, (N−). Among them, 303 sRNAs were significantly upregulated, whereas 115 sRNAs were significantly downregulated. RT-PCR of 18 randomly chosen sRNAs showed a similar pattern as RNA-seq result, which confirmed the reliability of the RNA-seq data. In addition, the possible target genes regulated by unique sRNAs of Anabaena sp. PCC 7120 under nitrogen addition (N+) condition or that under nitrogen depletion (N−) condition were analyzed for functional categorization and biological pathways, which provided the evidences that sRNAs were indeed involved in many different metabolic pathways.
Conclusion
The information from the present study provides a valuable reference for understanding the sRNA-mediated regulation of the nitrogen fixation in Anabaena PCC 7120 under steady state conditions.
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patD, a Gene Regulated by NtcA, Is Involved in the Optimization of Heterocyst Frequency in the Cyanobacterium Anabaena sp. Strain PCC 7120. J Bacteriol 2019; 201:JB.00457-19. [PMID: 31405917 DOI: 10.1128/jb.00457-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 08/04/2019] [Indexed: 11/20/2022] Open
Abstract
In the filamentous multicellular cyanobacterium Anabaena sp. strain PCC 7120, 5 to 10% of the cells differentiate into heterocysts, which are specialized in N2 fixation. Heterocysts and vegetative cells are mutually dependent for filament growth through nutrient exchange. Thus, the heterocyst frequency should be optimized to maintain the cellular carbon and nitrogen (C/N) balance for filament fitness in the environment. Here, we report the identification of patD, whose expression is directly activated in developing cells by the transcription factor NtcA. The inactivation of patD increases heterocyst frequency and promotes the upregulation of the positive regulator of heterocyst development hetR, whereas its overexpression decreases the heterocyst frequency. The change in heterocyst frequency resulting from the inactivation of patD leads to the reduction in competitiveness of the filaments under combined-nitrogen-depleted conditions. These results indicate that patD regulates heterocyst frequency in Anabaena sp. PCC 7120, ensuring its optimal filament growth.IMPORTANCE Microorganisms have evolved various strategies in order to adapt to the environment and compete with other organisms. Heterocyst differentiation is a prokaryotic model for studying complex cellular regulation. The NtcA-regulated gene patD controls the ratio of heterocysts relative to vegetative cells on the filaments of Anabaena sp. strain PCC 7120. Such a regulation provides a mechanism through which carbon fixation by vegetative cells and nitrogen fixation by heterocysts are properly balanced to ensure optimal growth and keep a competitive edge for long-term survival.
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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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Guío J, Sarasa-Buisan C, Velázquez-Campoy A, Bes MT, Fillat MF, Peleato ML, Sevilla E. 2-oxoglutarate modulates the affinity of FurA for the ntcA promoter in Anabaena sp. PCC 7120. FEBS Lett 2019; 594:278-289. [PMID: 31538336 DOI: 10.1002/1873-3468.13610] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 09/13/2019] [Accepted: 09/14/2019] [Indexed: 11/11/2022]
Abstract
2-oxoglutarate (2-OG) is a central metabolite that acts as a signaling molecule informing about the status of the carbon/nitrogen balance of the cell. In recent years, some transcriptional regulators and even two-component systems have been described as 2-OG sensors. In the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, two master regulators, NtcA and FurA, are deeply involved in the regulation of nitrogen metabolism. Both of them show a complex intertwined regulatory circuit to achieve a suitable regulation of nitrogen fixation. In this work, 2-OG is found to bind FurA, modulating the specific binding of FurA to the ntcA promoter. This study provides evidence of a new additional control point in the complex network controlled by the NtcA and FurA proteins.
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Affiliation(s)
- Jorge Guío
- Departamento de Bioquímica y Biología Molecular y Celular, Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Spain
| | - Cristina Sarasa-Buisan
- Departamento de Bioquímica y Biología Molecular y Celular, Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- Departamento de Bioquímica y Biología Molecular y Celular, Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Spain.,Aragon Institute for Health Research (IIS Aragon), Zaragoza, Spain.,Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain.,Fundacion ARAID, Government of Aragon, Zaragoza, Spain
| | - María Teresa Bes
- Departamento de Bioquímica y Biología Molecular y Celular, Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Spain
| | - María F Fillat
- Departamento de Bioquímica y Biología Molecular y Celular, Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Spain
| | - María Luisa Peleato
- Departamento de Bioquímica y Biología Molecular y Celular, Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Spain
| | - Emma Sevilla
- Departamento de Bioquímica y Biología Molecular y Celular, Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Spain
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Abstract
The filamentous cyanobacterium Anabaena can form heterocysts specialized in N2 fixation, mostly through a cascade of transcriptional activation in response to the nitrogen starvation signal 2-oxoglutarate. It is reported now that a transcription repressor, CalA, acts as a safety device to prevent heterocyst development under certain conditions where the 2-oxoglutarate level may touch the threshold to trigger unnecessary initiation of heterocyst development. Such a control may increase the fitness of Anabaena under a constantly changing environment.
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cyAbrB Transcriptional Regulators as Safety Devices To Inhibit Heterocyst Differentiation in Anabaena sp. Strain PCC 7120. J Bacteriol 2019; 201:JB.00244-19. [PMID: 31085690 DOI: 10.1128/jb.00244-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Accepted: 05/07/2019] [Indexed: 12/17/2022] Open
Abstract
Cyanobacteria are monophyletic organisms that perform oxygenic photosynthesis. While they exhibit great diversity, they have a common set of genes. However, the essentiality of them for viability has hampered the elucidation of their functions. One example of these genes is cyabrB1 (also known as calA in Anabaena sp. strain PCC 7120), encoding a transcriptional regulator. In the present study, we investigated the function of calA/cyabrB1 in the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 through CRISPR interference, a method that we recently utilized for the photosynthetic production of a useful chemical in this strain. Conditional knockdown of calA/cyabrB1 in the presence of nitrate resulted in the formation of heterocysts. Two genes, hetP and hepA, which are required for heterocyst formation, were upregulated by calA/cyabrB1 knockdown in the presence of combined nitrogen sources. These genes are known to be induced by HetR, a master regulator of heterocyst formation. hetR was not induced by calA/cyabrB1 knockdown. hetP and hepA were repressed by direct binding of CalA/cyAbrB1 to their promoter regions in a HetR-independent manner. In addition, the overexpression of calA/cyabrB1 abolished heterocyst formation upon nitrogen depletion. Also, knockout of calB/cyabrB2 (a paralogue gene of calA/cyabrB1), in addition to knockdown of calA/cyabrB1, enhanced heterocyst formation in the presence of nitrate, suggesting functional redundancy of cyAbrB proteins. We propose that a balance between amounts of HetR and CalA/cyAbrB1 is a key factor influencing heterocyst differentiation during nitrogen stepdown. We concluded that cyAbrB proteins are essential safety devices that inhibit heterocyst differentiation.IMPORTANCE Spore formation in Bacillus subtilis and Streptomyces has been extensively studied as models of prokaryotic nonterminal cell differentiation. In these organisms, many cells/hyphae differentiate simultaneously, which is governed by a network in which one regulator stands at the top. Differentiation of heterocysts in Anabaena sp. strain PCC 7120 is unique because it is terminal, and only 5 to 10% of vegetative cells differentiate into heterocysts. In this study, we identified CalA/cyAbrB1 as a repressor of two genes that are essential for heterocyst formation independently of HetR, a master activator for heterocyst differentiation. This finding is reasonable for unique cell differentiation of Anabaena because CalA/cyAbrB1 could suppress heterocyst differentiation tightly in vegetative cells, while only cells in which HetR is overexpressed could differentiate into heterocysts.
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Flores E, Picossi S, Valladares A, Herrero A. Transcriptional regulation of development in heterocyst-forming cyanobacteria. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:673-684. [DOI: 10.1016/j.bbagrm.2018.04.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 04/27/2018] [Accepted: 04/27/2018] [Indexed: 01/02/2023]
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Hampel JJ, McCarthy MJ, Neudeck M, Bullerjahn GS, McKay RML, Newell SE. Ammonium recycling supports toxic Planktothrix blooms in Sandusky Bay, Lake Erie: Evidence from stable isotope and metatranscriptome data. HARMFUL ALGAE 2019; 81:42-52. [PMID: 30638497 DOI: 10.1016/j.hal.2018.11.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/10/2018] [Accepted: 11/16/2018] [Indexed: 05/03/2023]
Abstract
Sandusky Bay, Lake Erie, receives high nutrient loadings (nitrogen and phosphorus) from the Sandusky River, which drains an agricultural watershed. Eutrophication and cyanobacterial harmful algal blooms (cyanoHABs) persist throughout summer. Planktothrix agardhii is the dominant bloom-forming species and the main producer of microcystins in Sandusky Bay. Non-N2 fixing cyanobacteria, such as Planktothrix and Microcystis, thrive on chemically reduced forms of nitrogen, such as ammonium (NH4+) and urea. Ammonium regeneration and potential uptake rates and total microbial community demand for NH4+ were quantified in Sandusky Bay. Potential NH4+ uptake rates in the light increased from June to August at all stations. Dark uptake rates also increased seasonally and, by the end of August, were on par with light uptake rates. Regeneration rates followed a similar pattern and were significantly higher in August than June. Ammonium uptake kinetics during a Planktothrix-dominated bloom in Sandusky Bay and a Microcystis-dominated bloom in Maumee Bay were also compared. The highest half saturation constant (Km) in Sandusky Bay was measured in June and decreased throughout the season. In contrast, Km values in Maumee Bay were lowest at the beginning of summer and increased in October. A significant increase in Vmax in Sandusky Bay was observed between July and the end of August, reflective of intense competition for depleted NH4+. Metatranscriptome results from Sandusky Bay show a shift from cyanophycin synthetase (luxury NH4+ uptake; cphA1) expression in early summer to cyanophycinase (intracellular N mobilization; cphB/cphA2) expression in August, supporting the interpretation that the microbial community is nitrogen-starved in late summer. Combined, our results show that, in late summer, when nitrogen concentrations are low, cyanoHABs in Sandusky Bay rely on regenerated NH4+ to support growth and toxin production. Increased dark NH4+ uptake late in summer suggests an important heterotrophic contribution to NH4+ depletion in the phycosphere. Kinetic experiments in the two bays suggest a competitive advantage for Planktothrix over Microcystis in Sandusky Bay due to its higher affinity for NH4+ at low concentrations.
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Affiliation(s)
- Justyna J Hampel
- Department of Earth & Environmental Sciences, Wright State University, Dayton, OH, United States.
| | - Mark J McCarthy
- Department of Earth & Environmental Sciences, Wright State University, Dayton, OH, United States
| | - Michelle Neudeck
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, United States
| | - George S Bullerjahn
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, United States
| | - Robert Michael L McKay
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, United States
| | - Silvia E Newell
- Department of Earth & Environmental Sciences, Wright State University, Dayton, OH, United States
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Zhang CC, Zhou CZ, Burnap RL, Peng L. Carbon/Nitrogen Metabolic Balance: Lessons from Cyanobacteria. TRENDS IN PLANT SCIENCE 2018; 23:1116-1130. [PMID: 30292707 DOI: 10.1016/j.tplants.2018.09.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 09/07/2018] [Accepted: 09/11/2018] [Indexed: 05/20/2023]
Abstract
Carbon and nitrogen are the two most abundant nutrient elements for all living organisms, and their metabolism is tightly coupled. What are the signaling mechanisms that cells use to sense and control the carbon/nitrogen (C/N) metabolic balance following environmental changes? Based on studies in cyanobacteria, it was found that 2-phosphoglycolate derived from the oxygenase activity of Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) and 2-oxoglutarate from the Krebs cycle act as the carbon- and nitrogen-starvation signals, respectively, and their concentration ratio likely reflects the status of the C/N metabolic balance. We will present and discuss the regulatory principles underlying the signaling mechanisms, which are likely to be conserved in other photosynthetic organisms. These concepts may also contribute to developments in the field of biofuel engineering or improvements in crop productivity.
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Affiliation(s)
- Cheng-Cai Zhang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, People's Republic of China; Aix-Marseille Université, CNRS, LCB, France.
| | - Cong-Zhao Zhou
- School of Life Sciences and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230027, People's Republic of China
| | - Robert L Burnap
- Department of Microbiology and Molecular Genetics, Henry Bellmon Research Center, Oklahoma State University, Stillwater, OK 74078, USA
| | - Ling Peng
- Aix-Marseille Université, CNRS, Centre Interdisciplinaire de Nanoscience de Marseille, Equipe Labellisée Ligue Contre le Cancer, CINaM UMR 7325, 13288 Marseille, France
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Forcada-Nadal A, Llácer JL, Contreras A, Marco-Marín C, Rubio V. The P II-NAGK-PipX-NtcA Regulatory Axis of Cyanobacteria: A Tale of Changing Partners, Allosteric Effectors and Non-covalent Interactions. Front Mol Biosci 2018; 5:91. [PMID: 30483512 PMCID: PMC6243067 DOI: 10.3389/fmolb.2018.00091] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 10/18/2018] [Indexed: 11/13/2022] Open
Abstract
PII, a homotrimeric very ancient and highly widespread (bacteria, archaea, plants) key sensor-transducer protein, conveys signals of abundance or poorness of carbon, energy and usable nitrogen, converting these signals into changes in the activities of channels, enzymes, or of gene expression. PII sensing is mediated by the PII allosteric effectors ATP, ADP (and, in some organisms, AMP), 2-oxoglutarate (2OG; it reflects carbon abundance and nitrogen scarcity) and, in many plants, L-glutamine. Cyanobacteria have been crucial for clarification of the structural bases of PII function and regulation. They are the subject of this review because the information gathered on them provides an overall structure-based view of a PII regulatory network. Studies on these organisms yielded a first structure of a PII complex with an enzyme, (N-acetyl-Lglutamate kinase, NAGK), deciphering how PII can cause enzyme activation, and how it promotes nitrogen stockpiling as arginine in cyanobacteria and plants. They have also revealed the first clear-cut mechanism by which PII can control gene expression. A small adaptor protein, PipX, is sequestered by PII when nitrogen is abundant and is released when is scarce, swapping partner by binding to the 2OG-activated transcriptional regulator NtcA, co-activating it. The structures of PII-NAGK, PII-PipX, PipX alone, of NtcA in inactive and 2OG-activated forms and as NtcA-2OG-PipX complex, explain structurally PII regulatory functions and reveal the changing shapes and interactions of the T-loops of PII depending on the partner and on the allosteric effectors bound to PII. Cyanobacterial studies have also revealed that in the PII-PipX complex PipX binds an additional transcriptional factor, PlmA, thus possibly expanding PipX roles beyond NtcA-dependency. Further exploration of these roles has revealed a functional interaction of PipX with PipY, a pyridoxal-phosphate (PLP) protein involved in PLP homeostasis whose mutations in the human ortholog cause epilepsy. Knowledge of cellular levels of the different components of this PII-PipX regulatory network and of KD values for some of the complexes provides the basic background for gross modeling of the system at high and low nitrogen abundance. The cyanobacterial network can guide searches for analogous components in other organisms, particularly of PipX functional analogs.
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Affiliation(s)
- Alicia Forcada-Nadal
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas, Valencia, Spain.,Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain
| | - José Luis Llácer
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas, Valencia, Spain.,Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras - Instituto de Salud Carlos III, Valencia, Spain
| | - Asunción Contreras
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain
| | - Clara Marco-Marín
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas, Valencia, Spain.,Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras - Instituto de Salud Carlos III, Valencia, Spain
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas, Valencia, Spain.,Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras - Instituto de Salud Carlos III, Valencia, Spain
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36
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Bolay P, Muro-Pastor MI, Florencio FJ, Klähn S. The Distinctive Regulation of Cyanobacterial Glutamine Synthetase. Life (Basel) 2018; 8:E52. [PMID: 30373240 PMCID: PMC6316151 DOI: 10.3390/life8040052] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 10/23/2018] [Accepted: 10/25/2018] [Indexed: 12/02/2022] Open
Abstract
Glutamine synthetase (GS) features prominently in bacterial nitrogen assimilation as it catalyzes the entry of bioavailable nitrogen in form of ammonium into cellular metabolism. The classic example, the comprehensively characterized GS of enterobacteria, is subject to exquisite regulation at multiple levels, among them gene expression regulation to control GS abundance, as well as feedback inhibition and covalent modifications to control enzyme activity. Intriguingly, the GS of the ecologically important clade of cyanobacteria features fundamentally different regulatory systems to those of most prokaryotes. These include the interaction with small proteins, the so-called inactivating factors (IFs) that inhibit GS linearly with their abundance. In addition to this protein interaction-based regulation of GS activity, cyanobacteria use alternative elements to control the synthesis of GS and IFs at the transcriptional level. Moreover, cyanobacteria evolved unique RNA-based regulatory mechanisms such as glutamine riboswitches to tightly tune IF abundance. In this review, we aim to outline the current knowledge on the distinctive features of the cyanobacterial GS encompassing the overall control of its activity, sensing the nitrogen status, transcriptional and post-transcriptional regulation, as well as strain-specific differences.
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Affiliation(s)
- Paul Bolay
- Helmholtz Centre for Environmental Research, Department of Solar Materials, Permoserstrasse 15, D-04318 Leipzig, Germany.
| | - M Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Américo Vespucio 49, E-41092 Seville, Spain.
| | - Francisco J Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Américo Vespucio 49, E-41092 Seville, Spain.
| | - Stephan Klähn
- Helmholtz Centre for Environmental Research, Department of Solar Materials, Permoserstrasse 15, D-04318 Leipzig, Germany.
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37
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Biosensors-Based In Vivo Quantification of 2-Oxoglutarate in Cyanobacteria and Proteobacteria. Life (Basel) 2018; 8:life8040051. [PMID: 30373229 PMCID: PMC6315671 DOI: 10.3390/life8040051] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 10/24/2018] [Accepted: 10/25/2018] [Indexed: 01/12/2023] Open
Abstract
2-oxoglutarate (α-ketoglutarate; 2-OG) is an intermediate of the Krebs cycle, and constitutes the carbon skeleton for nitrogen assimilation and the synthesis of a variety of compounds. In addition to being an important metabolite, 2-OG is a signaling molecule with a broad regulatory repertoire in a variety of organisms, including plants, animals, and bacteria. Although challenging, measuring the levels and variations of metabolic signals in vivo is critical to better understand how cells control specific processes. To measure cellular 2-OG concentrations and dynamics, we designed a set of biosensors based on the fluorescence resonance energy transfer (FRET) technology that can be used in vivo in different organisms. For this purpose, we took advantage of the conformational changes of two cyanobacterial proteins induced by 2-OG binding. We show that these biosensors responded immediately and specifically to different 2-OG levels, and hence allowed to measure 2-OG variations in function of environmental modifications in the proteobacterium Escherichia coli and in the cyanobacterium Anabaena sp. PCC 7120. Our results pave the way to study 2-OG dynamics at the cellular level in uni- and multi-cellular organisms.
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38
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Herrero A, Flores E. Genetic responses to carbon and nitrogen availability in Anabaena. Environ Microbiol 2018; 21:1-17. [PMID: 30066380 DOI: 10.1111/1462-2920.14370] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/27/2018] [Accepted: 07/29/2018] [Indexed: 11/27/2022]
Abstract
Heterocyst-forming cyanobacteria are filamentous organisms that perform oxygenic photosynthesis and CO2 fixation in vegetative cells and nitrogen fixation in heterocysts, which are formed under deprivation of combined nitrogen. These organisms can acclimate to use different sources of nitrogen and respond to different levels of CO2 . Following work mainly done with the best studied heterocyst-forming cyanobacterium, Anabaena, here we summarize the mechanisms of assimilation of ammonium, nitrate, urea and N2 , the latter involving heterocyst differentiation, and describe aspects of CO2 assimilation that involves a carbon concentration mechanism. These processes are subjected to regulation establishing a hierarchy in the assimilation of nitrogen sources -with preference for the most reduced nitrogen forms- and a dependence on sufficient carbon. This regulation largely takes place at the level of gene expression and is exerted by a variety of transcription factors, including global and pathway-specific transcriptional regulators. NtcA is a CRP-family protein that adjusts global gene expression in response to the C-to-N balance in the cells, and PacR is a LysR-family transcriptional regulator (LTTR) that extensively acclimates the cells to oxygenic phototrophy. A cyanobacterial-specific transcription factor, HetR, is involved in heterocyst differentiation, and other LTTR factors are specifically involved in nitrate and CO2 assimilation.
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Affiliation(s)
- Antonia Herrero
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Américo Vespucio 49, E-41092, Seville, Spain
| | - Enrique Flores
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Américo Vespucio 49, E-41092, Seville, Spain
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39
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Popova AA, Rasmussen U, Semashko TA, Govorun VM, Koksharova OA. Stress effects of cyanotoxin β-methylamino-L-alanine (BMAA) on cyanobacterial heterocyst formation and functionality. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:369-377. [PMID: 29624906 DOI: 10.1111/1758-2229.12647] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/28/2018] [Accepted: 04/01/2018] [Indexed: 06/08/2023]
Abstract
Various species of cyanobacteria, diatoms and dinoflagellates are capable of synthesizing the non-proteinogenic neurotoxic amino acid β-N-methylamino-L-alanine (BMAA), which is known to be a causative agent of human neurodegeneration. Similar to most cyanotoxins, the biological and ecological functions of BMAA in cyanobacteria are unknown. In this study, we show for the first time that BMAA, in micromolar amounts, inhibits the formation of heterocysts (specialized nitrogen-fixing cells) in heterocystous, diazotrophic cyanobacteria [Anabaena sp. PCC 7120, Nostoc punctiforme PCC 73102 (ATCC 29133), Nostoc sp. strain 8963] under conditions of nitrogen starvation. The inhibitory effect of BMAA is abolished by the addition of glutamate. To understand the genetic reason for the observed phenomenon, we used qPCR to study the expression of key genes involved in cell differentiation and nitrogen metabolism in the model cyanobacterium Anabaena sp. PCC 7120. We observed that in the presence of BMAA, Anabaena sp. PCC 7120 does not express two essential genes associated with heterocyst differentiation, namely, hetR and hepA. We also found that addition of BMAA to cyanobacterial cultures with mature heterocysts inhibits nifH gene expression and nitrogenase activity.
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Affiliation(s)
- Alexandra A Popova
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square, 2, 123182 Moscow, Russia
| | - Ulla Rasmussen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden
| | - Tatiana A Semashko
- Scientific-Research Institute of Physical-Chemical Medicine, Moscow 119435, Russia
| | - Vadim M Govorun
- Scientific-Research Institute of Physical-Chemical Medicine, Moscow 119435, Russia
| | - Olga A Koksharova
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square, 2, 123182 Moscow, Russia
- Lomonosov Moscow State University, Belozersky Institute of Physical-Chemical Biology, Leninskie Gory, 1, 40, Moscow, 119992, Russia
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40
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Teramoto T, Azai C, Terauchi K, Yoshimura M, Ohta T. Soft X-Ray Imaging of Cellular Carbon and Nitrogen Distributions in Heterocystous Cyanobacteria. PLANT PHYSIOLOGY 2018; 177:52-61. [PMID: 29581180 PMCID: PMC5933111 DOI: 10.1104/pp.17.01767] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/20/2018] [Indexed: 05/29/2023]
Abstract
Soft x-ray microscopy (SXM) is a minimally invasive technique for single-cell high-resolution imaging as well as the visualization of intracellular distributions of light elements such as carbon, nitrogen, and oxygen. We used SXM to observe photosynthesis and nitrogen fixation in the filamentous cyanobacterium Anabaena sp. PCC 7120, which can form heterocysts during nitrogen starvation. Statistical and spectroscopic analyses from SXM images around the K-absorption edge of nitrogen revealed a significant difference in the carbon-to-nitrogen (C/N) ratio between vegetative cells and heterocysts. Application of this analysis to soft x-ray images of Anabaena sp. PCC 7120 revealed inhomogenous C/N ratios in the cells. Furthermore, soft x-ray tomography of Anabaena sp. PCC 7120 revealed differing cellular C/N ratios, indicating different carbon and nitrogen distributions between vegetative cells and heterocysts in three dimensions.
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Affiliation(s)
- Takahiro Teramoto
- College of Science and Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan
| | - Chihiro Azai
- College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Japan
| | - Kazuki Terauchi
- College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Japan
| | | | - Toshiaki Ohta
- SR Center, Ritsumeikan University, Kusatsu 525-8577, Japan
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41
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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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42
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Wang Y, Feng H, Zhu Y, Gao P. Structural insights into glutathione-mediated activation of the master regulator PrfA in Listeria monocytogenes. Protein Cell 2018; 8:308-312. [PMID: 28271443 PMCID: PMC5359189 DOI: 10.1007/s13238-017-0390-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Affiliation(s)
- Yong Wang
- Key Laboratory of Infection and Immunity, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Han Feng
- Key Laboratory of Infection and Immunity, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yalan Zhu
- Key Laboratory of Infection and Immunity, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pu Gao
- Key Laboratory of Infection and Immunity, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
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43
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Domínguez-Martín MA, López-Lozano A, Clavería-Gimeno R, Velázquez-Campoy A, Seidel G, Burkovski A, Díez J, García-Fernández JM. Differential NtcA Responsiveness to 2-Oxoglutarate Underlies the Diversity of C/N Balance Regulation in Prochlorococcus. Front Microbiol 2018; 8:2641. [PMID: 29375510 PMCID: PMC5767323 DOI: 10.3389/fmicb.2017.02641] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 12/19/2017] [Indexed: 11/29/2022] Open
Abstract
Previous studies showed differences in the regulatory response to C/N balance in Prochlorococcus with respect to other cyanobacteria, but no information was available about its causes, or the ecological advantages conferred to thrive in oligotrophic environments. We addressed the changes in key enzymes (glutamine synthetase, isocitrate dehydrogenase) and the ntcA gene (the global nitrogen regulator) involved in C/N metabolism and its regulation, in three model Prochlorococcus strains: MED4, SS120, and MIT9313. We observed a remarkable level of diversity in their response to azaserine, a glutamate synthase inhibitor which increases the concentration of the key metabolite 2-oxoglutarate, used to sense the C/N balance by cyanobacteria. Besides, we studied the binding between the global nitrogen regulator (NtcA) and the promoter of the glnA gene in the same Prochlorococcus strains, and its dependence on the 2-oxoglutarate concentration, by using isothermal titration calorimetry, surface plasmon resonance, and electrophoretic mobility shift. Our results show a reduction in the responsiveness of NtcA to 2-oxoglutarate in Prochlorococcus, especially in the MED4 and SS120 strains. This suggests a trend to streamline the regulation of C/N metabolism in late-branching Prochlorococcus strains (MED4 and SS120), in adaptation to the rather stable conditions found in the oligotrophic ocean gyres where this microorganism is most abundant.
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Affiliation(s)
- María A Domínguez-Martín
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Córdoba, Spain
| | - Antonio López-Lozano
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Córdoba, Spain
| | - Rafael Clavería-Gimeno
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Units BIFI-IQFR-CSIC and GBsC-BIFI-CSIC, Universidad de Zaragoza, Zaragoza, Spain.,Aragon Institute for Health Research (IIS Aragon), Zaragoza, Spain.,Instituto Aragonés de Ciencias de la Salud, Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Units BIFI-IQFR-CSIC and GBsC-BIFI-CSIC, Universidad de Zaragoza, Zaragoza, Spain.,Aragon Institute for Health Research (IIS Aragon), Zaragoza, Spain.,Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Barcelona, Spain.,Fundación ARAID, Gobierno de Aragón, Zaragoza, Spain
| | - Gerald Seidel
- Professur für Mikrobiologie, Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Burkovski
- Professur für Mikrobiologie, Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jesús Díez
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Córdoba, Spain
| | - José M García-Fernández
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Córdoba, Spain
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44
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Coordinating carbon and nitrogen metabolic signaling through the cyanobacterial global repressor NdhR. Proc Natl Acad Sci U S A 2017; 115:403-408. [PMID: 29279392 DOI: 10.1073/pnas.1716062115] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The coordination of carbon and nitrogen metabolism is essential for bacteria to adapt to nutritional variations in the environment, but the underlying mechanism remains poorly understood. In autotrophic cyanobacteria, high CO2 levels favor the carboxylase activity of ribulose 1,5 bisphosphate carboxylase/oxygenase (RuBisCO) to produce 3-phosphoglycerate, whereas low CO2 levels promote the oxygenase activity of RuBisCO, leading to 2-phosphoglycolate (2-PG) production. Thus, the 2-PG level is reversely correlated with that of 2-oxoglutarate (2-OG), which accumulates under a high carbon/nitrogen ratio and acts as a nitrogen-starvation signal. The LysR-type transcriptional repressor NAD(P)H dehydrogenase regulator (NdhR) controls the expression of genes related to carbon metabolism. Based on genetic and biochemical studies, we report here that 2-PG is an inducer of NdhR, while 2-OG is a corepressor, as found previously. Furthermore, structural analyses indicate that binding of 2-OG at the interface between the two regulatory domains (RD) allows the NdhR tetramer to adopt a repressor conformation, whereas 2-PG binding to an intradomain cleft of each RD triggers drastic conformational changes leading to the dissociation of NdhR from its target DNA. We further confirmed the effect of 2-PG or 2-OG levels on the transcription of the NdhR regulon. Together with previous findings, we propose that NdhR can sense 2-OG from the Krebs cycle and 2-PG from photorespiration, two key metabolites that function together as indicators of intracellular carbon/nitrogen status, thus representing a fine sensor for the coordination of carbon and nitrogen metabolism in cyanobacteria.
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45
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Banerjee S, Subramanian A, Chattopadhyay J, Sarkar RR. Exploring the role of GS-GOGAT cycle in microcystin synthesis and regulation - a model based analysis. MOLECULAR BIOSYSTEMS 2017; 13:2603-2614. [PMID: 29034927 DOI: 10.1039/c7mb00342k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Toxic cyanobacteria blooms populate water bodies by consuming external nutrients and releasing cyanotoxins that are detrimental for other aquatic species, producing a significant impact on the plankton ecosystem and food web. To exercise population-level control of toxin production, understanding the biochemical mechanisms that explain cyanotoxin regulation within a bacterial cell is of utmost importance. In this study, we explore the mechanistic events to investigate the dependence of toxin microcystin on external nitrogen, a known regulator of the toxin, and for the first time, propose a kinetic model that analyzes the intracellular conditions required to ensure nitrogen dependence on microcystin. We hypothesize that the GS-GOGAT cycle is manipulated by variable influx of different intracellular metabolites that can either disturb or promote the balance between the enzyme microcystin synthetase and substrate glutamate to produce variable microcystin levels. As opposed to the popular notion that nitrogen starvation increases microcystin synthesis, our analyses suggest that under certain intracellular metabolite regimes, this relationship can either be completely lost or reversed. External nitrogen can only complement the conditions fixed by intracellular glutamate, glutamine and 2-oxoglutarate. This mechanistic understanding can provide an experimentally testable hypothesis for exploring the less-known biology of microcystin synthesis and designing specific interventions.
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Affiliation(s)
- Swarnendu Banerjee
- Agricultural and Ecological Research Unit, Indian Statistical Institute, 203, B. T. Road, Kolkata 700108, India
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46
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Ehira S, Shimmori Y, Watanabe S, Kato H, Yoshikawa H, Ohmori M. The nitrogen-regulated response regulator NrrA is a conserved regulator of glycogen catabolism in β-cyanobacteria. Microbiology (Reading) 2017; 163:1711-1719. [DOI: 10.1099/mic.0.000549] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Shigeki Ehira
- Department of Biological Science, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan
| | - Yuka Shimmori
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan
| | - Satoru Watanabe
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
| | - Hiroaki Kato
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
| | - Hirofumi Yoshikawa
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
| | - Masayuki Ohmori
- Department of Biological Science, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
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47
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Esteves-Ferreira AA, Inaba M, Obata T, Fort A, Fleming GTA, Araújo WL, Fernie AR, Sulpice R. A Novel Mechanism, Linked to Cell Density, Largely Controls Cell Division in Synechocystis. PLANT PHYSIOLOGY 2017; 174:2166-2182. [PMID: 28646084 PMCID: PMC5543973 DOI: 10.1104/pp.17.00729] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 06/20/2017] [Indexed: 05/28/2023]
Abstract
Many studies have investigated the various genetic and environmental factors regulating cyanobacterial growth. Here, we investigated the growth and metabolism of Synechocystis sp. PCC 6803 under different nitrogen sources, light intensities, and CO2 concentrations. Cells grown on urea showed the highest growth rates. However, for all conditions tested, the daily growth rates in batch cultures decreased steadily over time, and stationary phase was obtained with similar cell densities. Unexpectedly, metabolic and physiological analyses showed that growth rates during log phase were not controlled primarily by the availability of photoassimilates. Further physiological investigations indicated that nutrient limitation, quorum sensing, light quality, and light intensity (self-shading) were not the main factors responsible for the decrease in the growth rate and the onset of the stationary phase. Moreover, cell division rates in fed-batch cultures were positively correlated with the dilution rates. Hence, not only light, CO2, and nutrients can affect growth but also a cell-cell interaction. Accordingly, we propose that cell-cell interaction may be a factor responsible for the gradual decrease of growth rates in batch cultures during log phase, culminating with the onset of stationary phase.
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Affiliation(s)
- Alberto A Esteves-Ferreira
- National University of Ireland-Galway, Plant Systems Biology Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, Galway, Ireland
- CAPES Foundation, Ministry of Education of Brazil, Brasilia DF 70040 020, Brazil
| | - Masami Inaba
- National University of Ireland-Galway, Plant Systems Biology Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, Galway, Ireland
| | - Toshihiro Obata
- Central Metabolism Laboratory, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Max Planck Society, 14476 Potsdam-Golm, Germany
| | - Antoine Fort
- National University of Ireland-Galway, Genetics and Biotechnology Research Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, Galway, Ireland
| | - Gerard T A Fleming
- National University of Ireland-Galway, Microbiology, School of Natural Sciences, Galway, Ireland
| | - Wagner L Araújo
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Vicosa, Minas Gerais, Brazil
| | - Alisdair R Fernie
- Central Metabolism Laboratory, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Max Planck Society, 14476 Potsdam-Golm, Germany
| | - Ronan Sulpice
- National University of Ireland-Galway, Plant Systems Biology Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, Galway, Ireland
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48
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Muro-Pastor AM, Brenes-Álvarez M, Vioque A. A combinatorial strategy of alternative promoter use during differentiation of a heterocystous cyanobacterium. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:449-458. [PMID: 28585763 DOI: 10.1111/1758-2229.12555] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 05/24/2017] [Accepted: 05/29/2017] [Indexed: 06/07/2023]
Abstract
Heterocystous cyanobacteria such as Nostoc sp. are filamentous photosynthetic organisms that, in response to nitrogen deficiency, undergo a differentiation process transforming certain, semi-regularly spaced cells into heterocysts, devoted to nitrogen fixation. During transition to a nitrogen-fixing regime, growth of most vegetative cells in the filament is temporarily arrested due to nutritional deprivation, but developing heterocysts require intense transcriptional activity. Therefore, the coexistence of arrested vegetative cells and actively developing prospective heterocysts relies on the simultaneous operation of somewhat opposite transcriptional programs. We have identified genes with multiple nitrogen-responsive transcriptional starts appearing in seemingly paradoxical combinations. For instance, sigA, encoding the RNA polymerase housekeeping sigma factor, is transcribed from one major nitrogen stress-repressed promoter and from a second, nitrogen stress-induced promoter. Here, we show that both promoters are expressed with complementary temporal dynamics. Using a gfp reporter we also show that transcription from the inducible promoter takes place exclusively in differentiating heterocysts and is already detected before any morphological or fluorescence signature of differentiation is observed. Tandem promoters with opposite dynamics could operate a compensatory mechanism in which repression of transcription from the major promoter operative in vegetative cells is offset by transcription from a new promoter only in developing heterocyst.
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Affiliation(s)
- Alicia M Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, E-41092, Spain
| | - Manuel Brenes-Álvarez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, E-41092, Spain
| | - Agustín Vioque
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, E-41092, Spain
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49
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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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50
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Sandmann G, Mautz J, Breitenbach J. Control of light-dependent keto carotenoid biosynthesis in Nostoc 7120 by the transcription factor NtcA. ACTA ACUST UNITED AC 2017; 71:303-311. [PMID: 27564697 DOI: 10.1515/znc-2016-0117] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 07/19/2016] [Indexed: 11/15/2022]
Abstract
In Nostoc PCC 7120, two different ketolases, CrtW and CrtO are involved in the formation of keto carotenoids from β-carotene. In contrast to other cyanobacteria, CrtW catalyzes the formation of monoketo echinenone whereas CrtO is the only enzyme for the synthesis of diketo canthaxanthin. This is the major photo protective carotenoid in this cyanobacterium. Under high-light conditions, basic canthaxanthin formation was transcriptionally up-regulated. Upon transfer to high light, the transcript levels of all investigated carotenogenic genes including those coding for phytoene synthase, phytoene desaturase and both ketolases were increased. These transcription changes proceeded via binding of the transcription factor NtcA to the promoter regions of the carotenogenic genes. The binding was absolutely dependent on the presence of reductants and oxo-glutarate. Light-stimulated transcript formation was inhibited by DCMU. Therefore, photosynthetic electron transport is proposed as the sensor for high-light and a changing redox state as a signal for NtcA binding.
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