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Schätzle H, Arévalo S, Flores E, Schleiff E. A TonB-Like Protein, SjdR, Is Involved in the Structural Definition of the Intercellular Septa in the Heterocyst-Forming Cyanobacterium Anabaena. mBio 2021; 12:e0048321. [PMID: 34101487 PMCID: PMC8262864 DOI: 10.1128/mbio.00483-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 05/04/2021] [Indexed: 12/11/2022] Open
Abstract
Cyanobacteria are photosynthetic organisms with a Gram-negative envelope structure. Certain filamentous species such as Anabaena sp. strain PCC 7120 can fix dinitrogen upon depletion of combined nitrogen. Because the nitrogen-fixing enzyme, nitrogenase, is oxygen sensitive, photosynthesis and nitrogen fixation are spatially separated in Anabaena. Nitrogen fixation takes place in specialized cells called heterocysts, which differentiate from vegetative cells. During heterocyst differentiation, a microoxic environment is created by dismantling photosystem II and restructuring the cell wall. Moreover, solute exchange between the different cell types is regulated to limit oxygen influx into the heterocyst. The septal zone containing nanopores for solute exchange is constricted between heterocysts and vegetative cells, and cyanophycin plugs are located at the heterocyst poles. We identified a protein previously annotated as TonB1 that is largely conserved among cyanobacteria. A mutant of the encoding gene formed heterocysts but was impaired in diazotrophic growth. Mutant heterocysts appeared elongated and exhibited abnormal morphological features, including a reduced cyanophycin plug, an enhanced septum size, and a restricted nanopore zone in the septum. In spite of this, the intercellular transfer velocity of the fluorescent marker calcein was increased in the mutant compared to the wild type. Thus, the protein is required for proper formation of septal structures, expanding our emerging understanding of Anabaena peptidoglycan plasticity and intercellular solute exchange, and is therefore renamed SjdR (septal junction disk regulator). Notably, calcium supplementation compensated for the impaired diazotrophic growth and alterations in septal peptidoglycan in the sjdR mutant, emphasizing the importance of calcium for cell wall structure. IMPORTANCE Multicellularity in bacteria confers an improved adaptive capacity to environmental conditions and stresses. This includes an enhanced capability of resource utilization through a distribution of biochemical processes between constituent cells. This specialization results in a mutual dependency of different cell types, as is the case for nitrogen-fixing heterocysts and photosynthetically active vegetative cells in Anabaena. In this cyanobacterium, intercellular solute exchange is facilitated through nanopores in the peptidoglycan between adjacent cells. To ensure functionality of the specialized cells, septal size as well as the position, size, and frequency of nanopores in the septum need to be tightly established. The novel septal junction disk regulator SjdR characterized here is conserved in the cyanobacterial phylum. It influences septal size and septal nanopore distribution. Consequently, its absence severely affects the intercellular communication and the strains' growth capacity under nitrogen depletion. Thus, SjdR is involved in septal structure remodeling in cyanobacteria.
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Affiliation(s)
- Hannah Schätzle
- Institute for Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
- FIERCE, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Sergio Arévalo
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Seville, Spain
| | - Enrique Flores
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Seville, Spain
| | - Enrico Schleiff
- Institute for Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
- FIERCE, Goethe University Frankfurt, Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences, Frankfurt am Main, Germany
- Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany
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Machine Learning Establishes Single-Cell Calcium Dynamics as an Early Indicator of Antibiotic Response. Microorganisms 2021; 9:microorganisms9051000. [PMID: 34063175 PMCID: PMC8148219 DOI: 10.3390/microorganisms9051000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/28/2021] [Accepted: 04/30/2021] [Indexed: 11/17/2022] Open
Abstract
Changes in bacterial physiology necessarily precede cell death in response to antibiotics. Herein we investigate the early disruption of Ca2+ homeostasis as a marker for antibiotic response. Using a machine learning framework, we quantify the temporal information encoded in single-cell Ca2+ dynamics. We find Ca2+ dynamics distinguish kanamycin sensitive and resistant cells before changes in gross cell phenotypes such as cell growth or protein stability. The onset time (pharmacokinetics) and probability (pharmacodynamics) of these aberrant Ca2+ dynamics are dose and time-dependent, even at the resolution of single-cells. Of the compounds profiled, we find Ca2+ dynamics are also an indicator of Polymyxin B activity. In Polymyxin B treated cells, we find aberrant Ca2+ dynamics precedes the entry of propidium iodide marking membrane permeabilization. Additionally, we find modifying membrane voltage and external Ca2+ concentration alters the time between these aberrant dynamics and membrane breakdown suggesting a previously unappreciated role of Ca2+ in the membrane destabilization during Polymyxin B treatment. In conclusion, leveraging live, single-cell, Ca2+ imaging coupled with machine learning, we have demonstrated the discriminative capacity of Ca2+ dynamics in identifying antibiotic-resistant bacteria.
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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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Bryant DA, Shen G, Turner GM, Soulier N, Laremore TN, Ho MY. Far-red light allophycocyanin subunits play a role in chlorophyll d accumulation in far-red light. PHOTOSYNTHESIS RESEARCH 2020; 143:81-95. [PMID: 31760552 DOI: 10.1007/s11120-019-00689-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/31/2019] [Indexed: 06/10/2023]
Abstract
Some terrestrial cyanobacteria acclimate to and utilize far-red light (FRL; λ = 700-800 nm) for oxygenic photosynthesis, a process known as far-red light photoacclimation (FaRLiP). A conserved, 20-gene FaRLiP cluster encodes core subunits of Photosystem I (PSI) and Photosystem II (PSII), five phycobiliprotein subunits of FRL-bicylindrical cores, and enzymes for synthesis of chlorophyll (Chl) f and possibly Chl d. Deletion mutants for each of the five apc genes of the FaRLiP cluster were constructed in Synechococcus sp. PCC 7335, and all had similar phenotypes. When the mutants were grown in white (WL) or red (RL) light, the cells closely resembled the wild-type (WT) strain grown under the same conditions. However, the WT and mutant strains were very different when grown under FRL. Mutants grown in FRL were unable to assemble FRL-bicylindrical cores, were essentially devoid of FRL-specific phycobiliproteins, but retained RL-type phycobilisomes and WL-PSII. The transcript levels for genes of the FaRLiP cluster in the mutants were similar to those in WT. Surprisingly, the Chl d contents of the mutant strains were greatly reduced (~ 60-99%) compared to WT and so were the levels of FRL-PSII. We infer that Chl d may be essential for the assembly of FRL-PSII, which does not accumulate to normal levels in the mutants. We further infer that the cysteine-rich subunits of FRL allophycocyanin may either directly participate in the synthesis of Chl d or that FRL bicylindrical cores stabilize FRL-PSII to prevent loss of Chl d.
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Affiliation(s)
- Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA.
| | - Gaozhong Shen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Gavin M Turner
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Nathan Soulier
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Tatiana N Laremore
- Proteomics and Mass Spectrometry Core Facility, Huck Institute for the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Ming-Yang Ho
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Life Science, National Taiwan University, Taipei, 10617, Taiwan
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Kaczmarski JA, Hong NS, Mukherjee B, Wey LT, Rourke L, Förster B, Peat TS, Price GD, Jackson CJ. Structural Basis for the Allosteric Regulation of the SbtA Bicarbonate Transporter by the P II-like Protein, SbtB, from Cyanobium sp. PCC7001. Biochemistry 2019; 58:5030-5039. [PMID: 31746199 DOI: 10.1021/acs.biochem.9b00880] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cyanobacteria have evolved a suite of enzymes and inorganic carbon (Ci) transporters that improve photosynthetic performance by increasing the localized concentration of CO2 around the primary CO2-fixating enzyme, Rubisco. This CO2-concentrating mechanism (CCM) is highly regulated, responds to illumination/darkness cycles, and allows cyanobacteria to thrive under limiting Ci conditions. While the transcriptional control of CCM activity is well understood, less is known about how regulatory proteins might allosterically regulate Ci transporters in response to changing conditions. Cyanobacterial sodium-dependent bicarbonate transporters (SbtAs) are inhibited by PII-like regulatory proteins (SbtBs), with the inhibitory effect being modulated by adenylnucleotides. Here, we used isothermal titration calorimetry to show that SbtB from Cyanobium sp. PCC7001 (SbtB7001) binds AMP, ADP, cAMP, and ATP with micromolar-range affinities. X-ray crystal structures of apo and nucleotide-bound SbtB7001 revealed that while AMP, ADP, and cAMP have little effect on the SbtB7001 structure, binding of ATP stabilizes the otherwise flexible T-loop, and that the flexible C-terminal C-loop adopts several distinct conformations. We also show that ATP binding affinity is increased 10-fold in the presence of Ca2+, and we present an X-ray crystal structure of Ca2+ATP:SbtB7001 that shows how this metal ion facilitates additional stabilizing interactions with the apex of the T-loop. We propose that the Ca2+ATP-induced conformational change observed in SbtB7001 is important for allosteric regulation of SbtA activity by SbtB and is consistent with changing adenylnucleotide levels in illumination/darkness cycles.
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Affiliation(s)
- Joe A Kaczmarski
- Research School of Chemistry , The Australian National University , 137 Sullivans Creek Road , Canberra , ACT 0200 , Australia
| | - Nan-Sook Hong
- Research School of Chemistry , The Australian National University , 137 Sullivans Creek Road , Canberra , ACT 0200 , Australia
| | - Bratati Mukherjee
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology , The Australian National University , 134 Linnaeus Way , Canberra , ACT 0200 , Australia
| | - Laura T Wey
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology , The Australian National University , 134 Linnaeus Way , Canberra , ACT 0200 , Australia
| | - Loraine Rourke
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology , The Australian National University , 134 Linnaeus Way , Canberra , ACT 0200 , Australia
| | - Britta Förster
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology , The Australian National University , 134 Linnaeus Way , Canberra , ACT 0200 , Australia
| | - Thomas S Peat
- CSIRO Biomedical Program , 343 Royal Parade , Parkville , VIC 3052 , Australia
| | - G Dean Price
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology , The Australian National University , 134 Linnaeus Way , Canberra , ACT 0200 , Australia
| | - Colin J Jackson
- Research School of Chemistry , The Australian National University , 137 Sullivans Creek Road , Canberra , ACT 0200 , Australia
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Ho MY, Niedzwiedzki DM, MacGregor-Chatwin C, Gerstenecker G, Hunter CN, Blankenship RE, Bryant DA. Extensive remodeling of the photosynthetic apparatus alters energy transfer among photosynthetic complexes when cyanobacteria acclimate to far-red light. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1861:148064. [PMID: 31421078 DOI: 10.1016/j.bbabio.2019.148064] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 06/26/2019] [Accepted: 08/09/2019] [Indexed: 01/25/2023]
Abstract
Some cyanobacteria remodel their photosynthetic apparatus by a process known as Far-Red Light Photoacclimation (FaRLiP). Specific subunits of the phycobilisome (PBS), photosystem I (PSI), and photosystem II (PSII) complexes produced in visible light are replaced by paralogous subunits encoded within a conserved FaRLiP gene cluster when cells are grown in far-red light (FRL; λ = 700-800 nm). FRL-PSII complexes from the FaRLiP cyanobacterium, Synechococcus sp. PCC 7335, were purified and shown to contain Chl a, Chl d, Chl f, and pheophytin a, while FRL-PSI complexes contained only Chl a and Chl f. The spectroscopic properties of purified photosynthetic complexes from Synechococcus sp. PCC 7335 were determined individually, and energy transfer kinetics among PBS, PSII, and PSI were analyzed by time-resolved fluorescence (TRF) spectroscopy. Direct energy transfer from PSII to PSI was observed in cells (and thylakoids) grown in red light (RL), and possible routes of energy transfer in both RL- and FRL-grown cells were inferred. Three structural arrangements for RL-PSI were observed by atomic force microscopy of thylakoid membranes, but only arrays of trimeric FRL-PSI were observed in thylakoids from FRL-grown cells. Cells grown in FRL synthesized the FRL-specific complexes but also continued to synthesize some PBS and PSII complexes identical to those produced in RL. Although the light-harvesting efficiency of photosynthetic complexes produced in FRL might be lower in white light than the complexes produced in cells acclimated to white light, the FRL-complexes provide cells with the flexibility to utilize both visible and FRL to support oxygenic photosynthesis. This article is part of a Special Issue entitled Light harvesting, edited by Dr. Roberta Croce.
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Affiliation(s)
- Ming-Yang Ho
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA; Intercollege Graduate Program in Plant Biology, The Pennsylvania State University, University Park, PA, USA
| | - Dariusz M Niedzwiedzki
- Department of Energy, Environmental & Chemical Engineering and Center for Solar Energy and Energy Storage, Washington University, St. Louis, MO, USA
| | | | - Gary Gerstenecker
- Department of Energy, Environmental & Chemical Engineering and Center for Solar Energy and Energy Storage, Washington University, St. Louis, MO, USA
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Robert E Blankenship
- Department of Energy, Environmental & Chemical Engineering and Center for Solar Energy and Energy Storage, Washington University, St. Louis, MO, USA; Departments of Biology and Chemistry, Washington University, St. Louis, MO, USA
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA; Intercollege Graduate Program in Plant Biology, The Pennsylvania State University, University Park, PA, USA; Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA.
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Gao M, Ding BW, Liu YJ. Tuning the fluorescence of calcium-discharged photoprotein obelin via mutating at the His22-Phe88-Trp92 triad - a QM/MM study. Photochem Photobiol Sci 2019; 18:1823-1832. [PMID: 31165126 DOI: 10.1039/c9pp00191c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The fluorescence (FL) of calcium-discharged photoprotein (CaDP) can be altered by easily mutating CaDP without modifying coelenteramide (CLM), which is the decarboxylation product of coelenterazine in calcium-regulated photoprotein. The His22-Phe88-Trp92 triad (the ordering numbers of three amino acids are sorted by a crystal structure (PDB: 2F8P) of calcium-discharged obelin, i.e., CaDP-obelin) is closely related to CaDP-obelin FL, since it exists in close proximity to the 5-p-hydroxyphenyl of CLM. Therefore, it is important to thoroughly investigate how the mutations of this triad affect the emission color of CaDP-obelin FL. In this study, by mutating wild-type CaDP-obelin (WT) at the His22-Phe88-Trp92 triad, we theoretically constructed its nine mutants of separable FL colors. Through combined quantum mechanics and molecular mechanics (QM/MM) calculations and molecular dynamics (MD) simulations, the influence of the mutations of this triad on the CaDP-obelin FL was analyzed considering the H-bond effect and the charge effect. This study demonstrated that the mutations at the His22-Phe88-Trp92 triad redistribute the charges on the D-π-A molecule, CLM, change the charge transfer from the D to the (π + A) moiety, and thereby alter the FL emission. Appending more negative charges on the phenolate moiety of CLM benefits the FL redshift.
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Affiliation(s)
- Meng Gao
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, P. R. China.
| | - Bo-Wen Ding
- School of Environment, Beijing Normal University, Beijing, P. R. China
| | - Ya-Jun Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, P. R. China.
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Picciano AL, Crane BR. A nitric oxide synthase-like protein from Synechococcus produces NO/NO 3- from l-arginine and NADPH in a tetrahydrobiopterin- and Ca 2+-dependent manner. J Biol Chem 2019; 294:10708-10719. [PMID: 31113865 PMCID: PMC6615690 DOI: 10.1074/jbc.ra119.008399] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 05/17/2019] [Indexed: 01/01/2023] Open
Abstract
Nitric oxide synthases (NOSs) are heme-based monooxygenases that convert l-Arg to l-citrulline and nitric oxide (NO), a key signaling molecule and cytotoxic agent in mammals. Bacteria also contain NOS proteins, but the role of NO production within these organisms, where understood, differs considerably from that of mammals. For example, a NOS protein in the marine cyanobacterium Synechococcus sp. PCC 7335 (syNOS) has recently been proposed to function in nitrogen assimilation from l-Arg. syNOS retains the oxygenase (NOSox) and reductase (NOSred) domains present in mammalian NOS enzymes (mNOSs), but also contains an N-terminal globin domain (NOSg) homologous to bacterial flavohemoglobin proteins. Herein, we show that syNOS functions as a dimer and produces NO from l-Arg and NADPH in a tetrahydrobiopterin (H4B)-dependent manner at levels similar to those produced by other NOSs but does not require Ca2+-calmodulin, which regulates NOSred-mediated NOSox reduction in mNOSs. Unlike other bacterial NOSs, syNOS cannot function with tetrahydrofolate and requires high Ca2+ levels (>200 μm) for its activation. NOSg converts NO to NO3- in the presence of O2 and NADPH; however, NOSg did not protect Escherichia coli strains against nitrosative stress, even in a mutant devoid of NO-protective flavohemoglobin. We also found that syNOS does not have NOS activity in E. coli (which lacks H4B) and that the recombinant protein does not confer growth advantages on l-Arg as a nitrogen source. Our findings indicate that syNOS has both NOS and NO oxygenase activities, requires H4B, and may play a role in Ca2+-mediated signaling.
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Affiliation(s)
- Angela L Picciano
- From the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853
| | - Brian R Crane
- From the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853
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A novel Ca 2+-binding protein influences photosynthetic electron transport in Anabaena sp. PCC 7120. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:519-532. [PMID: 31034800 DOI: 10.1016/j.bbabio.2019.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/17/2019] [Accepted: 04/23/2019] [Indexed: 12/25/2022]
Abstract
Ca2+ is a potent signalling molecule that regulates many cellular processes. In cyanobacteria, Ca2+ has been linked to cell growth, stress response and photosynthesis, and to the development of specialist heterocyst cells in certain nitrogen-fixing species. Despite this, the pathways of Ca2+ signal transduction in cyanobacteria are poorly understood, and very few protein components are known. The current study describes a previously unreported Ca2+-binding protein which was called the Ca2+ Sensor EF-hand (CSE), which is conserved in filamentous, nitrogen-fixing cyanobacteria. CSE is shown to bind Ca2+, which induces a conformational change in the protein structure. Poor growth of a strain of Anabaena sp. PCC 7120 overexpressing CSE was attributed to diminished photosynthetic performance. Transcriptomics, biophysics and proteomics analyses revealed modifications in the light-harvesting phycobilisome and photosynthetic reaction centre protein complexes.
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A Novel Calcium Uptake Transporter of Uncharacterized P-Type ATPase Family Supplies Calcium for Cell Surface Integrity in Mycobacterium smegmatis. mBio 2017; 8:mBio.01388-17. [PMID: 28951477 PMCID: PMC5615198 DOI: 10.1128/mbio.01388-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ca2+ plays an important role in the physiology of bacteria. Intracellular Ca2+ concentrations are tightly maintained in the nanomolar range. Molecular mechanisms of Ca2+ uptake in bacteria remain elusive. Here we show that CtpE is responsible for Ca2+ uptake in Mycobacterium smegmatis. It represents a previously uncharacterized P-type ATPase family in bacteria. Disruption of ctpE in M. smegmatis resulted in a mutant with impaired growth under Ca2+-deficient conditions. The growth defect of the mutant could be rescued by Ca2+ or by ectopic expression of ctpE from M. smegmatis or the orthologous gene (Rv0908) from Mycobacterium tuberculosis H37Rv. Radioactive transport assays revealed that CtpE is a Ca2+-specific transporter. Ca2+ deficiency increased expression of ctpE, resulting in increased 45Ca2+ accumulation in cells. ctpE is a gene that is part of an operon, which is negatively regulated by Ca2+. The ctpE mutant also showed hypersensitivity to polymyxin B, increased biofilm formation, and higher cell aggregation, indicating cell envelope defects. Our work establishes, for the first time, the presence of Ca2+ uptake pumps of the energy-dependent P-type ATPase superfamily in bacteria and also implicates that intracellular Ca2+ is essential for growth and cell envelope integrity in M. smegmatis. Ca2+ is essential for gene regulation, enzymatic activity, and maintenance of structural integrity of cell walls in bacteria. Bacteria maintain intracellular calcium concentrations in a narrow range, creating a gradient with low cytoplasmic calcium concentration and high extracellular calcium concentration. Due to this steep gradient, active pumps belonging to family 2 of P-type ATPases and antiporters are used for Ca2+ efflux, whereas Ca2+ uptake is usually carried out by channels. Molecular mechanisms of Ca2+ uptake in bacteria are still elusive and are mainly limited to a nonproteinaceous channel in Escherichia coli and a pH-dependent channel protein from Bacillus subtilis. Energy-dependent active transporters are not reported for Ca2+ uptake from any organism. Here we show that CtpE belonging to a family of previously uncharacterized bacterial P-type ATPases is involved in specific uptake of Ca2+ into Mycobacterium smegmatis. We also demonstrate that intracellular Ca2+ obtained through CtpE is essential for growth and maintenance of cell surface properties under Ca2+-deficient conditions.
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Alieva RR, Kudryasheva NS. Variability of fluorescence spectra of coelenteramide-containing proteins as a basis for toxicity monitoring. Talanta 2017; 170:425-431. [PMID: 28501192 DOI: 10.1016/j.talanta.2017.04.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 04/10/2017] [Accepted: 04/16/2017] [Indexed: 11/30/2022]
Abstract
Nowadays, physicochemical approach to understanding toxic effects remains underdeveloped. A proper development of such mode would be concerned with simplest bioassay systems. Coelenteramide-Containing Fluorescent Proteins (CLM-CFPs) can serve as proper tools for study primary physicochemical processes in organisms under external exposures. CLM-CFPs are products of bioluminescent reactions of marine coelenterates. As opposed to Green Fluorescent Proteins, the CLM-CFPs are not widely applied in biomedical research, and their potential as colored biomarkers is undervalued now. Coelenteramide, fluorophore of CLM-CFPs, is a photochemically active molecule; it acts as a proton donor in its electron-excited states, generating several forms of different fluorescent state energy and, hence, different fluorescence color, from violet to green. Contributions of the forms to the visible fluorescence depend on the coelenteramide microenvironment in proteins. Hence, CLM-CFPs can serve as fluorescence biomarkers with color differentiation to monitor results of destructive biomolecule exposures. The paper reviews experimental and theoretical studies of spectral-luminescent and photochemical properties of CLM-CFPs, as well as their variation under different exposures - chemicals, temperature, and ionizing radiation. Application of CLM-CFPs as toxicity bioassays of a new type is justified.
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Affiliation(s)
- Roza R Alieva
- Institute of Biophysics SB RAS, Federal Research Center "Krasnoyarsk Science Center SB RAS", Akademgorodok 50/50, Krasnoyarsk 660036, Russia; Siberian Federal University, Svobodny Prospect 79, Krasnoyarsk 660041, Russia
| | - Nadezhda S Kudryasheva
- Institute of Biophysics SB RAS, Federal Research Center "Krasnoyarsk Science Center SB RAS", Akademgorodok 50/50, Krasnoyarsk 660036, Russia; Siberian Federal University, Svobodny Prospect 79, Krasnoyarsk 660041, Russia
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Ho MY, Gan F, Shen G, Zhao C, Bryant DA. Far-red light photoacclimation (FaRLiP) in Synechococcus sp. PCC 7335: I. Regulation of FaRLiP gene expression. PHOTOSYNTHESIS RESEARCH 2017; 131:173-186. [PMID: 27638320 DOI: 10.1007/s11120-016-0309-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 09/09/2016] [Indexed: 06/06/2023]
Abstract
Far-red light photoacclimation (FaRLiP) is a mechanism that allows some cyanobacteria to utilize far-red light (FRL) for oxygenic photosynthesis. During FaRLiP, cyanobacteria remodel photosystem (PS) I, PS II, and phycobilisomes while synthesizing Chl d, Chl f, and far-red-absorbing phycobiliproteins, and these changes enable these organisms to use FRL for growth. In this study, a conjugation-based genetic system was developed for Synechococcus sp. PCC 7335. Three antibiotic cassettes were successfully used to generate knockout mutations in genes in Synechococcus sp. PCC 7335, which should allow up to three gene loci to be modified in one strain. This system was used to delete the rfpA, rfpB, and rfpC genes individually, and characterization of the mutants demonstrated that these genes control the expression of the FaRLiP gene cluster in Synechococcus sp. PCC 7335. The mutant strains exhibited some surprising differences from similar mutants in other FaRLiP strains. Notably, mutations in any of the three master transcription regulatory genes led to enhanced synthesis of phycocyanin and PS II. A time-course study showed that acclimation of the photosynthetic apparatus from that produced in white light to that produced in FRL occurs very slowly over a period 12-14 days in this strain and that it is associated with a substantial reduction (~34 %) in the chlorophyll a content of the cells. This study shows that there are differences in the detailed responses of cyanobacteria to growth in FRL in spite of the obvious similarities in the organization and regulation of the FaRLiP gene cluster.
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Affiliation(s)
- Ming-Yang Ho
- 403C Althouse Laboratory, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
- Intercollege Graduate Degree Program in Plant Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Fei Gan
- 403C Althouse Laboratory, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Gaozhong Shen
- 403C Althouse Laboratory, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Chi Zhao
- 403C Althouse Laboratory, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Donald A Bryant
- 403C Althouse Laboratory, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
- Intercollege Graduate Degree Program in Plant Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA.
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13
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Ho MY, Shen G, Canniffe DP, Zhao C, Bryant DA. Light-dependent chlorophyll f synthase is a highly divergent paralog of PsbA of photosystem II. Science 2016; 353:science.aaf9178. [PMID: 27386923 DOI: 10.1126/science.aaf9178] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 06/22/2016] [Indexed: 12/22/2022]
Abstract
Chlorophyll f (Chl f) permits some cyanobacteria to expand the spectral range for photosynthesis by absorbing far-red light. We used reverse genetics and heterologous expression to identify the enzyme for Chl f synthesis. Null mutants of "super-rogue" psbA4 genes, divergent paralogs of psbA genes encoding the D1 core subunit of photosystem II, abolished Chl f synthesis in two cyanobacteria that grow in far-red light. Heterologous expression of the psbA4 gene, which we rename chlF, enables Chl f biosynthesis in Synechococcus sp. PCC 7002. Because the reaction requires light, Chl f synthase is probably a photo-oxidoreductase that employs catalytically useful Chl a molecules, tyrosine YZ, and plastoquinone (as does photosystem II) but lacks a Mn4Ca1O5 cluster. Introduction of Chl f biosynthesis into crop plants could expand their ability to use solar energy.
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Affiliation(s)
- Ming-Yang Ho
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA. Intercollege Graduate Degree Program in Plant Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Gaozhong Shen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Daniel P Canniffe
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Chi Zhao
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA. Intercollege Graduate Degree Program in Plant Biology, The Pennsylvania State University, University Park, PA 16802, USA. Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA. Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore.
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14
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Walter J, Lynch F, Battchikova N, Aro EM, Gollan PJ. Calcium impacts carbon and nitrogen balance in the filamentous cyanobacterium Anabaena sp. PCC 7120. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3997-4008. [PMID: 27012282 PMCID: PMC4915528 DOI: 10.1093/jxb/erw112] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Calcium is integral to the perception, communication and adjustment of cellular responses to environmental changes. However, the role of Ca(2+) in fine-tuning cellular responses of wild-type cyanobacteria under favourable growth conditions has not been examined. In this study, extracellular Ca(2+) has been altered, and changes in the whole transcriptome of Anabaena sp. PCC 7120 have been evaluated under conditions replete of carbon and combined nitrogen. Ca(2+) induced differential expression of many genes driving primary cellular metabolism, with transcriptional regulation of carbon- and nitrogen-related processes responding with opposing trends. However, physiological effects of these transcriptional responses on biomass accumulation, biomass composition, and photosynthetic activity over the 24h period following Ca(2+) adjustment were found to be minor. It is well known that intracellular carbon:nitrogen balance is integral to optimal cell growth and that Ca(2+) plays an important role in the response of heterocystous cyanobacteria to combined-nitrogen deprivation. This work adds to the current knowledge by demonstrating a signalling role of Ca(2+) for making sensitive transcriptional adjustments required for optimal growth under non-limiting conditions.
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Affiliation(s)
- Julia Walter
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland
| | - Fiona Lynch
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland
| | - Natalia Battchikova
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland
| | - Eva-Mari Aro
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland
| | - Peter J Gollan
- Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland
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15
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Expanding the Role of FurA as Essential Global Regulator in Cyanobacteria. PLoS One 2016; 11:e0151384. [PMID: 26967347 PMCID: PMC4788461 DOI: 10.1371/journal.pone.0151384] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 02/26/2016] [Indexed: 01/03/2023] Open
Abstract
In the nitrogen-fixing heterocyst-forming cyanobacterium Anabaena sp. PCC 7120, the ferric uptake regulator FurA plays a global regulatory role. Failures to eliminate wild-type copies of furA gene from the polyploid genome suggest essential functions. In the present study, we developed a selectively regulated furA expression system by the replacement of furA promoter in the Anabaena sp. chromosomes with the Co2+/Zn2+ inducible coaT promoter from Synechocystis sp. PCC 6803. By removing Co2+ and Zn2+ from the medium and shutting off furA expression, we showed that FurA was absolutely required for cyanobacterial growth. RNA-seq based comparative transcriptome analyses of the furA-turning off strain and its parental wild-type in conjunction with subsequent electrophoretic mobility shift assays and semi-quantitative RT-PCR were carried out in order to identify direct transcriptional targets and unravel new biological roles of FurA. The results of such approaches led us to identify 15 novel direct iron-dependent transcriptional targets belonging to different functional categories including detoxification and defences against oxidative stress, phycobilisome degradation, chlorophyll catabolism and programmed cell death, light sensing and response, heterocyst differentiation, exopolysaccharide biosynthesis, among others. Our analyses evidence novel interactions in the complex regulatory network orchestrated by FurA in cyanobacteria.
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16
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Zhao C, Gan F, Shen G, Bryant DA. RfpA, RfpB, and RfpC are the Master Control Elements of Far-Red Light Photoacclimation (FaRLiP). Front Microbiol 2015; 6:1303. [PMID: 26635768 PMCID: PMC4658448 DOI: 10.3389/fmicb.2015.01303] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/06/2015] [Indexed: 11/24/2022] Open
Abstract
Terrestrial cyanobacteria often occur in niches that are strongly enriched in far-red light (FRL; λ > 700 nm). Some cyanobacteria exhibit a complex and extensive photoacclimation response, known as FRL photoacclimation (FaRLiP). During the FaRLiP response, specialized paralogous proteins replace 17 core subunits of the three major photosynthetic complexes: Photosystem (PS) I, PS II, and the phycobilisome. Additionally, the cells synthesize both chlorophyll (Chl) f and Chl d. Using biparental mating from Escherichia coli, we constructed null mutants of three genes, rfpA, rfpB, and rfpC, in the cyanobacteria Chlorogloeopsis fritschii PCC 9212 and Chroococcidiopsis thermalis PCC 7203. The resulting mutants were no longer able to modify their photosynthetic apparatus to absorb FRL, were no longer able to synthesize Chl f, inappropriately synthesized Chl d in white light, and were unable to transcribe genes of the FaRLiP gene cluster. We conclude that RfpA, RfpB, and RfpC constitute a FRL-activated signal transduction cascade that is the master control switch for the FaRLiP response. FRL is proposed to activate (or inactivate) the histidine kinase activity of RfpA, which leads to formation of the active state of RfpB, the key response regulator and transcription activator. RfpC may act as a phosphate shuttle between RfpA and RfpB. Our results show that reverse genetics via conjugation will be a powerful approach in detailed studies of the FaRLiP response.
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Affiliation(s)
- Chi Zhao
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University University Park, PA, USA
| | - Fei Gan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University University Park, PA, USA
| | - Gaozhong Shen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University University Park, PA, USA
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University University Park, PA, USA ; Department of Chemistry and Biochemistry, Montana State University Bozeman, MT, USA
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17
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Moscatiello R, Zaccarin M, Ercolin F, Damiani E, Squartini A, Roveri A, Navazio L. Identification of ferredoxin II as a major calcium binding protein in the nitrogen-fixing symbiotic bacterium Mesorhizobium loti. BMC Microbiol 2015; 15:16. [PMID: 25648224 PMCID: PMC4322793 DOI: 10.1186/s12866-015-0352-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 01/16/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Legumes establish with rhizobial bacteria a nitrogen-fixing symbiosis which is of the utmost importance for both plant nutrition and a sustainable agriculture. Calcium is known to act as a key intracellular messenger in the perception of symbiotic signals by both the host plant and the microbial partner. Regulation of intracellular free Ca(2+) concentration, which is a fundamental prerequisite for any Ca(2+)-based signalling system, is accomplished by complex mechanisms including Ca(2+) binding proteins acting as Ca(2+) buffers. In this work we investigated the occurrence of Ca(2+) binding proteins in Mesorhizobium loti, the specific symbiotic partner of the model legume Lotus japonicus. RESULTS A soluble, low molecular weight protein was found to share several biochemical features with the eukaryotic Ca(2+)-binding proteins calsequestrin and calreticulin, such as Stains-all blue staining on SDS-PAGE, an acidic isoelectric point and a Ca(2+)-dependent shift of electrophoretic mobility. The protein was purified to homogeneity by an ammonium sulfate precipitation procedure followed by anion-exchange chromatography on DEAE-Cellulose and electroendosmotic preparative electrophoresis. The Ca(2+) binding ability of the M. loti protein was demonstrated by (45)Ca(2+)-overlay assays. ESI-Q-TOF MS/MS analyses of the peptides generated after digestion with either trypsin or endoproteinase AspN identified the rhizobial protein as ferredoxin II and confirmed the presence of Ca(2+) adducts. CONCLUSIONS The present data indicate that ferredoxin II is a major Ca(2+) binding protein in M. loti that may participate in Ca(2+) homeostasis and suggest an evolutionarily ancient origin for protein-based Ca(2+) regulatory systems.
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Affiliation(s)
- Roberto Moscatiello
- Department of Biology, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy.
| | - Mattia Zaccarin
- Department of Molecular Medicine, University of Padova, Viale G. Colombo 3, 35131, Padova, Italy.
| | - Flavia Ercolin
- Department of Biology, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy.
| | - Ernesto Damiani
- Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35131, Padova, Italy.
| | - Andrea Squartini
- Department of Agronomy, Food, Natural Resources, Animals and Environment, DAFNAE, University of Padova, Viale dell'Università 16, 35020, Legnaro, Padova, Italy.
| | - Antonella Roveri
- Department of Molecular Medicine, University of Padova, Viale G. Colombo 3, 35131, Padova, Italy.
| | - Lorella Navazio
- Department of Biology, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy.
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18
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Calcium binding proteins and calcium signaling in prokaryotes. Cell Calcium 2014; 57:151-65. [PMID: 25555683 DOI: 10.1016/j.ceca.2014.12.006] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 11/20/2022]
Abstract
With the continued increase of genomic information and computational analyses during the recent years, the number of newly discovered calcium binding proteins (CaBPs) in prokaryotic organisms has increased dramatically. These proteins contain sequences that closely resemble a variety of eukaryotic calcium (Ca(2+)) binding motifs including the canonical and pseudo EF-hand motifs, Ca(2+)-binding β-roll, Greek key motif and a novel putative Ca(2+)-binding domain, called the Big domain. Prokaryotic CaBPs have been implicated in diverse cellular activities such as division, development, motility, homeostasis, stress response, secretion, transport, signaling and host-pathogen interactions. However, the majority of these proteins are hypothetical, and only few of them have been studied functionally. The finding of many diverse CaBPs in prokaryotic genomes opens an exciting area of research to explore and define the role of Ca(2+) in organisms other than eukaryotes. This review presents the most recent developments in the field of CaBPs and novel advancements in the role of Ca(2+) in prokaryotes.
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19
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Survival strategies in the aquatic and terrestrial world: the impact of second messengers on cyanobacterial processes. Life (Basel) 2014; 4:745-69. [PMID: 25411927 PMCID: PMC4284465 DOI: 10.3390/life4040745] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/31/2014] [Accepted: 11/05/2014] [Indexed: 12/15/2022] Open
Abstract
Second messengers are intracellular substances regulated by specific external stimuli globally known as first messengers. Cells rely on second messengers to generate rapid responses to environmental changes and the importance of their roles is becoming increasingly realized in cellular signaling research. Cyanobacteria are photooxygenic bacteria that inhabit most of Earth's environments. The ability of cyanobacteria to survive in ecologically diverse habitats is due to their capacity to adapt and respond to environmental changes. This article reviews known second messenger-controlled physiological processes in cyanobacteria. Second messengers used in these systems include the element calcium (Ca2+), nucleotide-based guanosine tetraphosphate or pentaphosphate (ppGpp or pppGpp, represented as (p)ppGpp), cyclic adenosine 3',5'-monophosphate (cAMP), cyclic dimeric GMP (c-di-GMP), cyclic guanosine 3',5'-monophosphate (cGMP), and cyclic dimeric AMP (c-di-AMP), and the gaseous nitric oxide (NO). The discussion focuses on processes central to cyanobacteria, such as nitrogen fixation, light perception, photosynthesis-related processes, and gliding motility. In addition, we address future research trajectories needed to better understand the signaling networks and cross talk in the signaling pathways of these molecules in cyanobacteria. Second messengers have significant potential to be adapted as technological tools and we highlight possible novel and practical applications based on our understanding of these molecules and the signaling networks that they control.
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20
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Nomura H, Shiina T. Calcium signaling in plant endosymbiotic organelles: mechanism and role in physiology. MOLECULAR PLANT 2014; 7:1094-1104. [PMID: 24574521 DOI: 10.1093/mp/ssu020] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Recent studies have demonstrated that chloroplasts and mitochondria evoke specific Ca(2+) signals in response to biotic and abiotic stresses in a stress-dependent manner. The identification of Ca(2+) transporters and Ca(2+) signaling molecules in chloroplasts and mitochondria implies that they play roles in controlling not only intra-organellar functions, but also extra-organellar processes such as plant immunity and stress responses. It appears that organellar Ca(2+) signaling might be more important to plant cell functions than previously thought. This review briefly summarizes what is known about the molecular basis of Ca(2+) signaling in plant mitochondria and chloroplasts.
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Affiliation(s)
- Hironari Nomura
- Department of Health and Nutrition, Gifu Women's University, 80 Taromaru, Gifu 501-2592, Japan
| | - Takashi Shiina
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Sakyo-ku Kyoto 606-8522, Japan
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21
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Sarkisova SA, Lotlikar SR, Guragain M, Kubat R, Cloud J, Franklin MJ, Patrauchan MA. A Pseudomonas aeruginosa EF-hand protein, EfhP (PA4107), modulates stress responses and virulence at high calcium concentration. PLoS One 2014; 9:e98985. [PMID: 24918783 PMCID: PMC4053335 DOI: 10.1371/journal.pone.0098985] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 05/09/2014] [Indexed: 12/18/2022] Open
Abstract
Pseudomonas aeruginosa is a facultative human pathogen, and a major cause of nosocomial infections and severe chronic infections in endocarditis and in cystic fibrosis (CF) patients. Calcium (Ca2+) accumulates in pulmonary fluids of CF patients, and plays a role in the hyperinflammatory response to bacterial infection. Earlier we showed that P. aeruginosa responds to increased Ca2+ levels, primarily through the increased production of secreted virulence factors. Here we describe the role of putative Ca2+-binding protein, with an EF-hand domain, PA4107 (EfhP), in this response. Deletion mutations of efhP were generated in P. aeruginosa strain PAO1 and CF pulmonary isolate, strain FRD1. The lack of EfhP abolished the ability of P. aeruginosa PAO1 to maintain intracellular Ca2+ homeostasis. Quantitative high-resolution 2D-PAGE showed that the efhP deletion also affected the proteomes of both strains during growth with added Ca2+. The greatest proteome effects occurred when the pulmonary isolate was cultured in biofilms. Among the proteins that were significantly less abundant or absent in the mutant strains were proteins involved in iron acquisition, biosynthesis of pyocyanin, proteases, and stress response proteins. In support, the phenotypic responses of FRD1 ΔefhP showed that the mutant strain lost its ability to produce pyocyanin, developed less biofilm, and had decreased resistance to oxidative stress (H2O2) when cultured at high [Ca2+]. Furthermore, the mutant strain was unable to produce alginate when grown at high [Ca2+] and no iron. The effect of the ΔefhP mutations on virulence was determined in a lettuce model of infection. Growth of wild-type P. aeruginosa strains at high [Ca2+] causes an increased area of disease. In contrast, the lack of efhP prevented this Ca2+-induced increase in the diseased zone. The results indicate that EfhP is important for Ca2+ homeostasis and virulence of P. aeruginosa when it encounters host environments with high [Ca2+].
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Affiliation(s)
- Svetlana A. Sarkisova
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Shalaka R. Lotlikar
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Manita Guragain
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Ryan Kubat
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - John Cloud
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Michael J. Franklin
- Department of Microbiology, Montana State University, Bozeman, Montana, United States of America
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, United States of America
| | - Marianna A. Patrauchan
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, United States of America
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22
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Singh S, Mishra AK. Regulation of calcium ion and its effect on growth and developmental behavior in wild type and ntcA mutant of Anabaena sp. PCC 7120 under varied levels of CaCl2. Microbiology (Reading) 2014. [DOI: 10.1134/s002626171403014x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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23
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Alieva RR, Belogurova NV, Petrova AS, Kudryasheva NS. Effects of alcohols on fluorescence intensity and color of a discharged-obelin-based biomarker. Anal Bioanal Chem 2014; 406:2965-74. [PMID: 24618986 DOI: 10.1007/s00216-014-7685-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 02/05/2014] [Accepted: 02/07/2014] [Indexed: 10/25/2022]
Abstract
Photoproteins are responsible for bioluminescence of marine coelenterates; bioluminescent and fluorescent biomarkers based on photoproteins are useful for monitoring of calcium-dependent processes in medical investigations. Here, we present the analysis of intensity and color of light-induced fluorescence of Ca(2+)-discharged photoprotein obelin in the presence of alcohols (ethanol and glycerol). Complex obelin spectra obtained at different concentrations of the alcohols at 350- and 280-nm excitation (corresponding to polypeptide-bound coelenteramide and tryptophan absorption regions) were deconvoluted into Gaussian components; fluorescent intensity and contributions of the components to experimental spectra were analyzed. Five Gaussian components were found in different spectral regions-ultraviolet (tryptophan emission), blue-green (coelenteramide emission), and red (hypothetical indole-coelenteramide exciplex emission). Inhibition coefficients and contributions of the components to experimental fluorescent spectra showed that presence of alcohols increased contributions of ultraviolet, violet, and red components, but decreased contributions of components in the blue-green region. The effects were related to (1) changes of proton transfer efficiency in fluorescent S*1 state of coelenteramide in the obelin active center and (2) formation of indole-coelenteramide exciplex at 280-nm photoexcitation. The data show that variation of fluorescence color and intensity in the presence of alcohols and dependence of emission spectra on excitation wavelength should be considered while applying the discharged obelin as a fluorescence biomarker.
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Affiliation(s)
- Roza R Alieva
- Siberian Federal University, Svobodny Prospect 79, 660041, Krasnoyarsk, Russia
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24
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Li L, Nan J, Li D, Brostromer E, Wang Z, Liu C, Hou Q, Fan X, Ye Z, Su XD. Structural genomics studies of human caries pathogen Streptococcus mutans. ACTA ACUST UNITED AC 2014; 15:91-9. [PMID: 24474570 DOI: 10.1007/s10969-014-9172-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 01/17/2014] [Indexed: 10/25/2022]
Abstract
Gram-positive bacterium Streptococcus mutans is the primary causative agent of human dental caries. To better understand this pathogen at the atomic structure level and to establish potential drug and vaccine targets, we have carried out structural genomics research since 2005. To achieve the goal, we have developed various in-house automation systems including novel high-throughput crystallization equipment and methods, based on which a large-scale, high-efficiency and low-cost platform has been establish in our laboratory. From a total of 1,963 annotated open reading frames, 1,391 non-membrane targets were selected prioritized by protein sequence similarities to unknown structures, and clustered by restriction sites to allow for cost-effective high-throughput conventional cloning. Selected proteins were over-expressed in different strains of Escherichia coli. Clones expressed soluble proteins were selected, expanded, and expressed proteins were purified and subjected to crystallization trials. Finally, protein crystals were subjected to X-ray analysis and structures were determined by crystallographic methods. Using the previously established procedures, we have so far obtained more than 200 kinds of protein crystals and 100 kinds of crystal structures involved in different biological pathways. In this paper we demonstrate and review a possibility of performing structural genomics studies at moderate laboratory scale. Furthermore, the techniques and methods developed in our study can be widely applied to conventional structural biology research practice.
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Affiliation(s)
- Lanfen Li
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, 100871, China,
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25
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Fan XX, Zhou YF, Liu X, Li LF, Su XD. Ellman's reagent in promoting crystallization and structure determination of Anabaena CcbP. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:1409-14. [PMID: 23143261 PMCID: PMC3515393 DOI: 10.1107/s1744309112034938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 08/07/2012] [Indexed: 06/01/2023]
Abstract
Obtaining crystals presented a bottleneck in the structural study of Anabaena cyanobacterial Ca2+-binding protein (CcbP). In this report, the promoting effect of Ellman's reagent [5,5'-dithiobis(2-nitrobenzoic acid); DTNB] on the crystallization of CcbP is described. CcbP contains one free cysteine. A quick and simple oxidation reaction with DTNB blocked the free cysteine in purified CcbP and generated a homogenous monomeric protein for crystallization. The crystal structure of DTNB-modified CcbP was determined by the single-wavelength anomalous diffraction method. Structure analysis indicated that DTNB modification facilitated crystallization of CcbP by inducing polar interactions in the crystal lattice. DTNB-mediated cysteine modification was demonstrated to have little effect on the overall structure and the Ca2+ binding of CcbP. Thus, DTNB modification may provide a simple and general approach for protein modification to improve the success of crystallization screening.
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Affiliation(s)
- Xue-Xin Fan
- State Key Laboratory of Protein and Plant Gene Research, and Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, No. 5 Yiheyuan Road, Beijing 100871, People’s Republic of China
| | - Yan-Feng Zhou
- Immune Disease Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Xiang Liu
- The High Throughput Molecular Drug Discovery Center, Tianjin International Joint Academy of Biotechnology and Medicine, 220 DongTing Road, Tianjin 300457, People’s Republic of China
| | - Lan-Fen Li
- State Key Laboratory of Protein and Plant Gene Research, and Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, No. 5 Yiheyuan Road, Beijing 100871, People’s Republic of China
| | - Xiao-Dong Su
- State Key Laboratory of Protein and Plant Gene Research, and Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, No. 5 Yiheyuan Road, Beijing 100871, People’s Republic of China
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Muro-Pastor AM, Hess WR. Heterocyst differentiation: from single mutants to global approaches. Trends Microbiol 2012; 20:548-57. [DOI: 10.1016/j.tim.2012.07.005] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 07/08/2012] [Accepted: 07/12/2012] [Indexed: 02/05/2023]
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Stael S, Wurzinger B, Mair A, Mehlmer N, Vothknecht UC, Teige M. Plant organellar calcium signalling: an emerging field. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:1525-42. [PMID: 22200666 PMCID: PMC3966264 DOI: 10.1093/jxb/err394] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
This review provides a comprehensive overview of the established and emerging roles that organelles play in calcium signalling. The function of calcium as a secondary messenger in signal transduction networks is well documented in all eukaryotic organisms, but so far existing reviews have hardly addressed the role of organelles in calcium signalling, except for the nucleus. Therefore, a brief overview on the main calcium stores in plants-the vacuole, the endoplasmic reticulum, and the apoplast-is provided and knowledge on the regulation of calcium concentrations in different cellular compartments is summarized. The main focus of the review will be the calcium handling properties of chloroplasts, mitochondria, and peroxisomes. Recently, it became clear that these organelles not only undergo calcium regulation themselves, but are able to influence the Ca(2+) signalling pathways of the cytoplasm and the entire cell. Furthermore, the relevance of recent discoveries in the animal field for the regulation of organellar calcium signals will be discussed and conclusions will be drawn regarding potential homologous mechanisms in plant cells. Finally, a short overview on bacterial calcium signalling is included to provide some ideas on the question where this typically eukaryotic signalling mechanism could have originated from during evolution.
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Affiliation(s)
- Simon Stael
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
| | - Bernhard Wurzinger
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
| | - Andrea Mair
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
| | - Norbert Mehlmer
- Department of Biology I, Botany, LMU Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany
| | - Ute C. Vothknecht
- Department of Biology I, Botany, LMU Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany
- Center for Integrated Protein Science (Munich) at the Department of Biology of the LMU Munich, D-81377 Munich, Germany
| | - Markus Teige
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
- To whom correspondence should be addressed.
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Chouhan B, Denesyuk A, Heino J, Johnson MS, Denessiouk K. Conservation of the human integrin-type beta-propeller domain in bacteria. PLoS One 2011; 6:e25069. [PMID: 22022374 PMCID: PMC3192720 DOI: 10.1371/journal.pone.0025069] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 08/26/2011] [Indexed: 11/18/2022] Open
Abstract
Integrins are heterodimeric cell-surface receptors with key functions in cell-cell and cell-matrix adhesion. Integrin α and β subunits are present throughout the metazoans, but it is unclear whether the subunits predate the origin of multicellular organisms. Several component domains have been detected in bacteria, one of which, a specific 7-bladed β-propeller domain, is a unique feature of the integrin α subunits. Here, we describe a structure-derived motif, which incorporates key features of each blade from the X-ray structures of human αIIbβ3 and αVβ3, includes elements of the FG-GAP/Cage and Ca(2+)-binding motifs, and is specific only for the metazoan integrin domains. Separately, we searched for the metazoan integrin type β-propeller domains among all available sequences from bacteria and unicellular eukaryotic organisms, which must incorporate seven repeats, corresponding to the seven blades of the β-propeller domain, and so that the newly found structure-derived motif would exist in every repeat. As the result, among 47 available genomes of unicellular eukaryotes we could not find a single instance of seven repeats with the motif. Several sequences contained three repeats, a predicted transmembrane segment, and a short cytoplasmic motif associated with some integrins, but otherwise differ from the metazoan integrin α subunits. Among the available bacterial sequences, we found five examples containing seven sequential metazoan integrin-specific motifs within the seven repeats. The motifs differ in having one Ca(2+)-binding site per repeat, whereas metazoan integrins have three or four sites. The bacterial sequences are more conserved in terms of motif conservation and loop length, suggesting that the structure is more regular and compact than those example structures from human integrins. Although the bacterial examples are not full-length integrins, the full-length metazoan-type 7-bladed β-propeller domains are present, and sometimes two tandem copies are found.
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Affiliation(s)
- Bhanupratap Chouhan
- Department of Biosciences, Åbo Akademi University, Turku, Finland
- Turku Center for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland
| | | | - Jyrki Heino
- Department of Biochemistry and Food Chemistry, University of Turku, Turku, Finland
| | - Mark S. Johnson
- Department of Biosciences, Åbo Akademi University, Turku, Finland
| | - Konstantin Denessiouk
- Turku Center for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland
- * E-mail:
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Specific degradation of photosystem II D1 protein by a protease (Alr3815) in heterocysts of the cyanobacterium Anabaena sp. PCC7120. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s11434-010-4329-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Hu Y, Zhang X, Shi Y, Zhou Y, Zhang W, Su XD, Xia B, Zhao J, Jin C. Structures of Anabaena calcium-binding protein CcbP: insights into Ca2+ signaling during heterocyst differentiation. J Biol Chem 2011; 286:12381-8. [PMID: 21330362 DOI: 10.1074/jbc.m110.201186] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Ca2+-binding proteins play pivotal roles in both eukaryotic and prokaryotic cells. CcbP from cyanobacterium Anabaena sp. strain PCC 7120 is a major Ca2+-binding protein involved in heterocyst differentiation, a process that forms specialized nitrogen-fixing cells. The three-dimensional structures of both Ca2+-free and Ca2+-bound forms of CcbP are essential for elucidating the Ca2+-signaling mechanism. However, CcbP shares low sequence identity with proteins of known structures, and its Ca2+-binding sites remain unknown. Here, we report the solution structures of CcbP in both Ca2+-free and Ca2+-bound forms determined by nuclear magnetic resonance spectroscopy. CcbP adopts an overall new fold and contains two Ca2+-binding sites with distinct Ca2+-binding abilities. Mutation of Asp38 at the stronger Ca2+-binding site of CcbP abolished its ability to regulate heterocyst formation in vivo. Surprisingly, the β-barrel subdomain of CcbP, which does not participate in Ca2+-binding, topologically resembles the Src homology 3 (SH3) domain and might act as a protein-protein interaction module. Our results provide the structural basis of the unique Ca2+ signaling mechanism during heterocyst differentiation.
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Affiliation(s)
- Yunfei Hu
- Beijing Nuclear Magnetic Resonance Center, State Key Laboratory of Plant and Protein Engineering, College of Life Sciences, Peking University, Beijing, China
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Calcium and iron regulate swarming and type III secretion in Vibrio parahaemolyticus. J Bacteriol 2010; 192:6025-38. [PMID: 20851895 DOI: 10.1128/jb.00654-10] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Here, we probe the response to calcium during growth on a surface and show that calcium influences the transcriptome and stimulates motility and virulence of Vibrio parahaemolyticus. Swarming (but not swimming) gene expression and motility were enhanced by calcium. Calcium also elevated transcription of one of the organism's two type III secretion systems (T3SS1 but not T3SS2) and heightened cytotoxicity toward host cells in coculture. Calcium stimulation of T3SS gene expression has not been reported before, although low calcium is an inducing signal for the T3SS of many organisms. EGTA was also found to increase T3SS1 gene expression and virulence; however, this was demonstrated to be the consequence of iron rather than calcium chelation. Ectopic expression of exsA, encoding the T3SS1 AraC-type regulator, was used to define the extent of the T3SS1 regulon and verify its coincident induction by calcium and EGTA. To begin to understand the regulatory mechanisms modulating the calcium response, a calcium-repressed, LysR-type transcription factor named CalR was identified and shown to repress swarming and T3SS1 gene expression. Swarming and T3SS1 gene expression were also demonstrated to be linked by LafK, a σ(54)-dependent regulator of swarming, and additionally connected by a negative-feedback loop on the swarming regulon propagated by ExsA. Thus, calcium and iron, two ions pertinent for a marine organism and pathogen, play a signaling role with global consequences on the regulation of gene sets that are relevant for surface colonization and infection.
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Discharged photoprotein obelin: fluorescence peculiarities. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2010; 101:103-8. [PMID: 20678944 DOI: 10.1016/j.jphotobiol.2010.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 06/30/2010] [Accepted: 07/01/2010] [Indexed: 11/20/2022]
Abstract
Photoprotein obelin, the enzyme-substrate complex of polypeptide with 2-hydroperoxycoelenterazine, is responsible for bioluminescence of marine hydroid Obelia longissima. Addition of Ca(2+) to the photoprotein triggers the bioluminescent reaction with light emission. The product of the bioluminescent reaction--enzyme-bound coelenteramide--is a fluorescent protein called 'discharged' obelin. It is stable and highly fluorescent. The paper considers dependence of its light-induced fluorescence on Ca(2+) concentration. Increase of Ca(2+) concentration enhanced the fluorescence intensity of discharged obelin; the dependence was found as linear in double logarithmic coordinates at Ca(2+) concentration range 10(-7)-10(-6) M, both in excitation and emission spectra. The spectra were divided into components; contributions of the components to experimental excitation and emission spectra depended on Ca(2+) concentration. The data suggest enzymatic conformational transition in discharged obelin at approximately 5 x 10(-7) M of Ca(2+) concentration. Spectra variations were attributed to acidity changes of discharged obelin chromophore (coelenteramide) in its fluorescent state S(1)*.
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Abstract
Many multicellular cyanobacteria produce specialized nitrogen-fixing heterocysts. During diazotrophic growth of the model organism Anabaena (Nostoc) sp. strain PCC 7120, a regulated developmental pattern of single heterocysts separated by about 10 to 20 photosynthetic vegetative cells is maintained along filaments. Heterocyst structure and metabolic activity function together to accommodate the oxygen-sensitive process of nitrogen fixation. This article focuses on recent research on heterocyst development, including morphogenesis, transport of molecules between cells in a filament, differential gene expression, and pattern formation.
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Affiliation(s)
- Krithika Kumar
- Department of Biology, Texas A&M University, College Station, 77843, USA
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Stucken K, John U, Cembella A, Murillo AA, Soto-Liebe K, Fuentes-Valdés JJ, Friedel M, Plominsky AM, Vásquez M, Glöckner G. The smallest known genomes of multicellular and toxic cyanobacteria: comparison, minimal gene sets for linked traits and the evolutionary implications. PLoS One 2010; 5:e9235. [PMID: 20169071 PMCID: PMC2821919 DOI: 10.1371/journal.pone.0009235] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 01/14/2010] [Indexed: 11/24/2022] Open
Abstract
Cyanobacterial morphology is diverse, ranging from unicellular spheres or rods to multicellular structures such as colonies and filaments. Multicellular species represent an evolutionary strategy to differentiate and compartmentalize certain metabolic functions for reproduction and nitrogen (N2) fixation into specialized cell types (e.g. akinetes, heterocysts and diazocytes). Only a few filamentous, differentiated cyanobacterial species, with genome sizes over 5 Mb, have been sequenced. We sequenced the genomes of two strains of closely related filamentous cyanobacterial species to yield further insights into the molecular basis of the traits of N2 fixation, filament formation and cell differentiation. Cylindrospermopsis raciborskii CS-505 is a cylindrospermopsin-producing strain from Australia, whereas Raphidiopsis brookii D9 from Brazil synthesizes neurotoxins associated with paralytic shellfish poisoning (PSP). Despite their different morphology, toxin composition and disjunct geographical distribution, these strains form a monophyletic group. With genome sizes of approximately 3.9 (CS-505) and 3.2 (D9) Mb, these are the smallest genomes described for free-living filamentous cyanobacteria. We observed remarkable gene order conservation (synteny) between these genomes despite the difference in repetitive element content, which accounts for most of the genome size difference between them. We show here that the strains share a specific set of 2539 genes with >90% average nucleotide identity. The fact that the CS-505 and D9 genomes are small and streamlined compared to those of other filamentous cyanobacterial species and the lack of the ability for heterocyst formation in strain D9 allowed us to define a core set of genes responsible for each trait in filamentous species. We presume that in strain D9 the ability to form proper heterocysts was secondarily lost together with N2 fixation capacity. Further comparisons to all available cyanobacterial genomes covering almost the entire evolutionary branch revealed a common minimal gene set for each of these cyanobacterial traits.
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Affiliation(s)
- Karina Stucken
- Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
- Millenium Nucleus EMBA, Santiago, Chile
| | - Uwe John
- Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
| | - Allan Cembella
- Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
| | - Alejandro A. Murillo
- Department of Molecular Genetic and Microbiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millenium Nucleus EMBA, Santiago, Chile
| | - Katia Soto-Liebe
- Department of Molecular Genetic and Microbiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millenium Nucleus EMBA, Santiago, Chile
| | - Juan J. Fuentes-Valdés
- Department of Molecular Genetic and Microbiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millenium Nucleus EMBA, Santiago, Chile
| | - Maik Friedel
- Leibniz Institute for Age Research-Fritz Lipmann Institute, Jena, Germany
| | - Alvaro M. Plominsky
- Department of Molecular Genetic and Microbiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millenium Nucleus EMBA, Santiago, Chile
| | - Mónica Vásquez
- Department of Molecular Genetic and Microbiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millenium Nucleus EMBA, Santiago, Chile
- * E-mail: (MV); (GG)
| | - Gernot Glöckner
- Leibniz Institute for Age Research-Fritz Lipmann Institute, Jena, Germany
- Institute for Biochemistry I, University of Cologne, Cologne, Germany
- Leibniz Institute for Freshwater Ecology and Inland Fisheries, Berlin, Germany
- * E-mail: (MV); (GG)
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Flores E, Herrero A. Compartmentalized function through cell differentiation in filamentous cyanobacteria. Nat Rev Microbiol 2010; 8:39-50. [PMID: 19966815 DOI: 10.1038/nrmicro2242] [Citation(s) in RCA: 280] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Within the wide biodiversity that is found in the bacterial world, Cyanobacteria represents a unique phylogenetic group that is responsible for a key metabolic process in the biosphere - oxygenic photosynthesis - and that includes representatives exhibiting complex morphologies. Many cyanobacteria are multicellular, growing as filaments of cells in which some cells can differentiate to carry out specialized functions. These differentiated cells include resistance and dispersal forms as well as a metabolically specialized form that is devoted to N(2) fixation, known as the heterocyst. In this Review we address cyanobacterial intercellular communication, the supracellular structure of the cyanobacterial filament and the basic principles that govern the process of heterocyst differentiation.
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Affiliation(s)
- Enrique Flores
- Instituto de Bioqumica Vegetal y Fotosntesis, CSIC and Universidad de Sevilla, Amrico Vespucio 49, E41092 Seville, Spain.
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Leganés F, Forchhammer K, Fernández-Piñas F. Role of calcium in acclimation of the cyanobacterium Synechococcus elongatus PCC 7942 to nitrogen starvation. MICROBIOLOGY-SGM 2009; 155:25-34. [PMID: 19118343 DOI: 10.1099/mic.0.022251-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A Ca2+ signal is required for the process of heterocyst differentiation in the filamentous diazotrophic cyanobacterium Anabaena sp. PCC 7120. This paper presents evidence that a transient increase in intracellular free Ca2+ is also involved in acclimation to nitrogen starvation in the unicellular non-diazotrophic cyanobacterium Synechococcus elongatus PCC 7942. The Ca2+ transient was triggered in response to nitrogen step-down or the addition of 2-oxoglutarate (2-OG), or its analogues 2,2-difluoropentanedioic acid (DFPA) and 2-methylenepentanedioic acid (2-MPA), to cells growing with combined nitrogen, suggesting that an increase in intracellular 2-OG levels precedes the Ca2+ transient. The signalling protein P(II) and the transcriptional regulator NtcA appear to be needed to trigger the signal. Suppression of the Ca2+ transient by the intracellular Ca2+ chelator N,N'-[1,2-ethanediylbis(oxy-2,1-phenylene)]bis[N-[2-[(acetyloxy)methoxy]-2-oxoethyl]]-,bis[(acetyloxy)methyl] ester (BAPTA-AM) inhibited expression of the glnB and glnN genes, which are involved in acclimation to nitrogen starvation and transcriptionally activated by NtcA. BAPTA-AM treatment partially inhibited expression of the nblA gene, which is involved in phycobiliprotein degradation following nutrient starvation and is regulated by NtcA and NblR; in close agreement, BAPTA-AM treatment partially inhibited bleaching following nitrogen starvation. Taken together, the results presented here strongly suggest an involvement of a defined Ca2+ transient in acclimation of S. elongatus to nitrogen starvation through NtcA-dependent regulation.
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Affiliation(s)
- Francisco Leganés
- Departamento de Biología, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Karl Forchhammer
- Lehrstuhl für Mikrobiologie-Organismische Interaktionen, Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
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Abstract
Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that differentiates heterocysts in response to deprivation of combined nitrogen. A hetF deletion strain lacked heterocysts and had aberrant cell morphology. Site-directed mutagenesis of the predicted active-site histidine and cysteine residues of this putative caspase-hemoglobinase fold protease abolished HetF function, supporting the hypothesis that HetF is a protease. Deletion of patA, which is necessary for the formation of most intercalary heterocysts, or hetF resulted in an increase in HetR protein, and extra copies of hetF on a plasmid functionally bypassed the deletion of patA. A hetR-gfp translational fusion expressed from an inducible promoter demonstrated that hetF-dependent downregulation of HetR levels occurs rapidly in vegetative cells, as well as developing heterocysts. "Mosaic" filaments in which only one cell of a filament had a copy of hetR or hetF indicated that hetF is required for differentiation only in cells that will become heterocysts. hetF was required for transcription from a hetR-dependent transcription start point of the hetR promoter and induction of transcription from the patS promoter. The inverse correlation between the level of HetR protein and transcription from hetR-dependent promoters suggests that the transcriptional activity of HetR is regulated by HetF and PatA.
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Raymond J, Swingley WD. Phototroph genomics ten years on. PHOTOSYNTHESIS RESEARCH 2008; 97:5-19. [PMID: 18568416 DOI: 10.1007/s11120-008-9308-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Accepted: 04/23/2008] [Indexed: 05/26/2023]
Abstract
The onset of the genome era means different things to different people, but it is clear that this new age brings with it paradigm shifts that will forever affect biological research. Less clear is just how these shifts are changing the scope and scale of research. Are gigabases of raw data more useful than a single well-understood gene? Do we really need a full genome to understand the physiology of a single organism? The photosynthetic field is poised at the periphery of the bulk of genome sequencing work--understandably skewed toward health-related disciplines--and, as such, is subject to different motivations, limitations, and primary focus for each new genome. To understand some of these differences, we focus here on various indicators of the impact that genomics has had on the photosynthetic community, now a full decade since the publication of the first photosynthetic genome. Many useful indicators are indexed in public databases, providing pre- and post-genome sequence snapshots of changes in factors such as publication rate, number of proteins characterized, and sequenced genome coverage versus known diversity. As more genomes are sequenced and metagenomic projects begin to pour out billions of bases, it becomes crucial to understand how to harness this data in order to accumulate possible benefits and avoid possible pitfalls, especially as resources become increasingly directed toward natural environments governed by photosynthetic activity, ranging from hot springs to tropical forest ecosystems to the open ocean.
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Affiliation(s)
- Jason Raymond
- School of Natural Sciences, University of California, Merced, Merced, CA, USA.
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CabC, an EF-hand calcium-binding protein, is involved in Ca2+-mediated regulation of spore germination and aerial hypha formation in Streptomyces coelicolor. J Bacteriol 2008; 190:4061-8. [PMID: 18375559 DOI: 10.1128/jb.01954-07] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Ca(2+) was reported to regulate spore germination and aerial hypha formation in streptomycetes; the underlying mechanism of this regulation is not known. cabC, a gene encoding an EF-hand calcium-binding protein, was disrupted or overexpressed in Streptomyces coelicolor M145. On R5- agar, the disruption of cabC resulted in denser aerial hyphae with more short branches, swollen hyphal tips, and early-germinating spores on the spore chain, while cabC overexpression significantly delayed development. Manipulation of the Ca(2+) concentration in R5- agar could reverse the phenotypes of cabC disruption or overexpression mutants and mimic mutant phenotypes with M145, suggesting that the mutant phenotypes were due to changes in the intracellular Ca(2+) concentration. CabC expression was strongly activated in aerial hyphae, as determined by Western blotting against CabC and confocal laser scanning microscopy detection of CabC::enhanced green fluorescent protein (EGFP). CabC::EGFP fusion proteins were evenly distributed in substrate mycelia, aerial mycelia, and spores. Taken together, these results demonstrate that CabC is involved in Ca(2+)-mediated regulation of spore germination and aerial hypha formation in S. coelicolor. CabC most likely acts as a Ca(2+) buffer and exerts its regulatory effects by controlling the intracellular Ca(2+) concentration.
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Zhao W, Ye Z, Zhao J. RbrA, a cyanobacterial rubrerythrin, functions as a FNR-dependent peroxidase in heterocysts in protection of nitrogenase from damage by hydrogen peroxide in Anabaena sp. PCC 7120. Mol Microbiol 2008; 66:1219-30. [PMID: 18001348 DOI: 10.1111/j.1365-2958.2007.05994.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The heterocyst is a specialized cell for nitrogen fixation in some filamentous cyanobacteria. Here we report that a rubrerythrin (RbrA) from Anabaena sp. PCC 7120 functions as a peroxidase in heterocysts and plays an important role in protection of nitrogenase. The electron donor for RbrA in H(2)O(2) reduction is NADPH and the electron transfer from NADPH to RbrA depends on ferredoxin:NADP(+) oxidoreductase. A rbrA mutant (r27) grew much more slowly than the wild type under diazotrophic conditions. Its nitrogenase activity measured in air was only 8% of that measured under anoxic conditions. Staining r27 filaments with 2',7'-dichlorodihydrofluorescein diacetate indicated that heterocysts had a higher H(2)O(2) concentration than the vegetative cells. The expression of rbrA was controlled by two promoters and the promoter for the smaller transcript was regulated by HetR. Spatial expression of rbrA was studied and the results showed that the transcription is localized predominantly in heterocysts. In a mutant lacking nifH and rbrA, the H(2)O(2) concentration in heterocysts was lower than that in the vegetative cells, suggesting that NifH is involved in H(2)O(2) generation. Our results demonstrate that RbrA is a critical enzyme for H(2)O(2) decomposition and provide evidence that nitrogenase autoprotection is important in heterocysts.
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Affiliation(s)
- Weixing Zhao
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing, 100871, China
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Gao K, Yu H, Brown MT. Solar PAR and UV radiation affects the physiology and morphology of the cyanobacterium Anabaena sp. PCC 7120. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2007; 89:117-24. [DOI: 10.1016/j.jphotobiol.2007.09.006] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Revised: 09/05/2007] [Accepted: 09/13/2007] [Indexed: 10/22/2022]
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Zhang Y, Pu H, Wang Q, Cheng S, Zhao W, Zhang Y, Zhao J. PII Is Important in Regulation of Nitrogen Metabolism but Not Required for Heterocyst Formation in the Cyanobacterium Anabaena sp. PCC 7120. J Biol Chem 2007; 282:33641-33648. [PMID: 17875643 DOI: 10.1074/jbc.m706500200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PII is an important signal protein for regulation of nitrogen metabolism in bacteria and plants. We constructed a mutant of glnB, encoding PII, in a heterocystous cyanobacterium, Anabaena sp. PCC 7120, with a cre-loxP system. The mutant (MP2alpha) grew more slowly than the wild type under all nitrogen regimens. It excreted a large amount of ammonium when grown on nitrate due to altered activities of glutamine synthetase and nitrate reductase. MP2alpha had a low nitrogenase activity but was able to form heterocysts under diazotrophic conditions, suggesting that PII is not required for heterocyst differentiation. Analysis of the PII with mass spectroscopy found tyrosine nitration at Tyr-51 under diazotrophic conditions while no phosphorylation at Ser-49 was detected. The strains 51F and 49A, which have PII with mutations of Y51F and S49A, respectively, were constructed to analyze the functions of the two key residues on the T-loop. Like MP2alpha, they had low nitrogenase activity and grew slowly under diazotrophic conditions. 49A was also impaired in nitrate uptake and formed heterocysts in the presence of nitrate. The up-regulation of ntcA after nitrogen step-down, which was present in the wild type, was not observed in 51F and 49A. While our results showed that the Ser-49 residue is important to the function of PII in Anabaena sp. PCC 7120, evidence from the PII pattern of the wild type and 49A in non-denaturing gel electrophoresis suggested that Ser-49 is not modified. The possible physiological roles of tyrosine nitration of PII are discussed.
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Affiliation(s)
- Ying Zhang
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Hai Pu
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Qingsong Wang
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Shu Cheng
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Weixing Zhao
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Yan Zhang
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Jindong Zhao
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China.
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Hu B, Yang G, Zhao W, Zhang Y, Zhao J. MreB is important for cell shape but not for chromosome segregation of the filamentous cyanobacterium Anabaena sp. PCC 7120. Mol Microbiol 2007; 63:1640-52. [PMID: 17367385 DOI: 10.1111/j.1365-2958.2007.05618.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
MreB is a bacterial actin that plays important roles in determination of cell shape and chromosome partitioning in Escherichia coli and Caulobacter crescentus. In this study, the mreB from the filamentous cyanobacterium Anabaena sp. PCC 7120 was inactivated. Although the mreB null mutant showed a drastic change in cell shape, its growth rate, cell division and the filament length were unaltered. Thus, MreB in Anabaena maintains cell shape but is not required for chromosome partitioning. The wild type and the mutant had eight and 10 copies of chromosomes per cell respectively. We demonstrated that DNA content in two daughter cells after cell division in both strains was not always identical. The ratios of DNA content in two daughter cells had a Gaussian distribution with a standard deviation much larger than a value expected if the DNA content in two daughter cells were identical, suggesting that chromosome partitioning is a random process. The multiple copies of chromosomes in cyanobacteria are likely required for chromosome random partitioning in cell division.
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Affiliation(s)
- Bin Hu
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
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Jang J, Wang L, Jeanjean R, Zhang CC. PrpJ, a PP2C-type protein phosphatase located on the plasma membrane, is involved in heterocyst maturation in the cyanobacterium Anabaena sp. PCC 7120. Mol Microbiol 2007; 64:347-58. [PMID: 17371502 DOI: 10.1111/j.1365-2958.2007.05654.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein phosphatases play important roles in the regulation of cell growth, division and differentiation. The cyanobacterium Anabaena PCC 7120 is able to differentiate heterocysts specialized in nitrogen fixation. To protect the nitrogenase from inactivation by oxygen, heterocyst envelope possesses a layer of polysaccharide and a layer of glycolipids. In the present study, we characterized All1731 (PrpJ), a protein phosphatase from Anabaena PCC 7120. prpJ was constitutively expressed in both vegetative cells and heterocysts. Under diazotrophic conditions, the mutant DeltaprpJ (S20) did not grow, lacked only one of the two heterocyst glycolipids, and fragmented extensively at the junctions between developing cells and vegetative cells. No heterocyst glycolipid layer could be observed in the mutant by electron microscopy. The inactivation of prpJ affected the expression of hglE(A) and nifH, two genes necessary for the formation of the glycolipid layer of heterocysts and the nitrogenase respectively. PrpJ displayed a phosphatase activity characteristic of PP2C-type protein phosphatases, and was localized on the plasma membrane. The function of prpJ establishes a new control point for heterocyst maturation because it regulates the synthesis of only one of the two heterocyst glycolipids while all other genes so far analysed regulate the synthesis of both heterocyst glycolipids.
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Affiliation(s)
- Jichan Jang
- Laboratoire de Chimie Bactérienne, CNRS-UPR9043, Institut de Biologie Structurale et Microbiologie, 31 chemin Joseph Aiguier, 13402 Marseille cedex 20, France
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Koropatkin NM, Koppenaal DW, Pakrasi HB, Smith TJ. The structure of a cyanobacterial bicarbonate transport protein, CmpA. J Biol Chem 2006; 282:2606-14. [PMID: 17121816 DOI: 10.1074/jbc.m610222200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyanobacteria, blue-green algae, are the most abundant autotrophs in aquatic environments and form the base of the food chain by fixing carbon and nitrogen into cellular biomass. To compensate for the low selectivity of Rubisco for CO2 over O2, cyanobacteria have developed highly efficient CO2-concentrating machinery of which the ABC transport system CmpABCD from Synechocystis PCC 6803 is one component. Here, we have described the structure of the bicarbonate-binding protein CmpA in the absence and presence of bicarbonate and carbonic acid. CmpA is highly homologous to the nitrate transport protein NrtA. CmpA binds carbonic acid at the entrance to the ligand-binding pocket, whereas bicarbonate binds in nearly an identical location compared with nitrate binding to NrtA. Unexpectedly, bicarbonate binding is accompanied by a metal ion, identified as Ca2+ via inductively coupled plasma optical emission spectrometry. The binding of bicarbonate and metal appears to be highly cooperative and suggests that CmpA may co-transport bicarbonate and calcium or that calcium acts a cofactor in bicarbonate transport.
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Sakr S, Thyssen M, Denis M, Zhang CC. Relationship among several key cell cycle events in the developmental cyanobacterium Anabaena sp. strain PCC 7120. J Bacteriol 2006; 188:5958-65. [PMID: 16885464 PMCID: PMC1540088 DOI: 10.1128/jb.00524-06] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When grown in the absence of a source of combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 develops, within 24 h, a differentiated cell type called a heterocyst that is specifically involved in the fixation of N(2). Cell division is required for heterocyst development, suggesting that the cell cycle could control this developmental process. In this study, we investigated several key events of the cell cycle, such as cell growth, DNA synthesis, and cell division, and explored their relationships to heterocyst development. The results of analyses by flow cytometry indicated that the DNA content increased as the cell size expanded during cell growth. The DNA content of heterocysts corresponded to the subpopulation of vegetative cells that had a big cell size, presumably those at the late stages of cell growth. Consistent with these results, most proheterocysts exhibited two nucleoids, which were resolved into a single nucleoid in most mature heterocysts. The ring structure of FtsZ, a protein required for the initiation of bacterial cell division, was present predominantly in big cells and rarely in small cells. When cell division was inhibited and consequently cells became elongated, little change in DNA content was found by measurement using flow cytometry, suggesting that inhibition of cell division may block further synthesis of DNA. The overexpression of minC, which encodes an inhibitor of FtsZ polymerization, led to the inhibition of cell division, but cells expanded in spherical form to become giant cells; structures with several cells attached together in the form of a cloverleaf could be seen frequently. These results may indicate that the relative amounts of FtsZ and MinC affect not only cell division but also the placement of the cell division planes and the cell morphology. MinC overexpression blocked heterocyst differentiation, consistent with the requirement of cell division in the control of heterocyst development.
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Affiliation(s)
- Samer Sakr
- Laboratoire de Chimie Bactérienne, CNRS-UPR 9043, Institut de Biologie Structurale et Microbiologie, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France
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Shi Y, Zhao W, Zhang W, Ye Z, Zhao J. Regulation of intracellular free calcium concentration during heterocyst differentiation by HetR and NtcA in Anabaena sp. PCC 7120. Proc Natl Acad Sci U S A 2006; 103:11334-9. [PMID: 16849429 PMCID: PMC1544087 DOI: 10.1073/pnas.0602839103] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Calcium ions are important to some prokaryotic cellular processes, such as heterocyst differentiation of cyanobacteria. Intracellular free Ca(2+)concentration, [Ca(2+)](i), increases several fold in heterocysts and is regulated by CcbP, a Ca(2+)-binding protein found in heterocyst-forming cyanobacteria. We demonstrate here that CcbP is degraded by HetR, a serine-type protease that controls heterocyst differentiation. The degradation depends on Ca(2+) and appears to be specific because HetR did not digest other tested proteins. CcbP was found to bind two Ca(2+) per molecule with K(D) values of 200 nM and 12.8 microM. Degradation of CcbP releases bound Ca(2+) that contributes significantly to the increase of [Ca(2+)](i) during the process of heterocyst differentiation in Anabaena sp. strain PCC 7120. We suggest that degradation of CcbP is a mechanism of positive autoregulation of HetR. The down-regulation of ccbP in differentiating cells and mature heterocysts, which also is critical to the regulation of [Ca(2+)](i), depends on NtcA. Coexpression of ntcA and a ccbP promoter-controlled gfp in Escherichia coli diminished production of GFP, and the decrease is enhanced by alpha-ketoglutarate. It was also found that NtcA could bind a fragment of the ccbP promoter containing an NtcA-binding sequence in a alpha-ketoglutarate-dependent fashion. Therefore, [Ca(2+)](i) is regulated by a collaboration of HetR and NtcA in heterocyst differentiation in Anabaena sp. strain PCC 7120.
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Affiliation(s)
- Yunming Shi
- State Key Lab of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Weixing Zhao
- State Key Lab of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Wei Zhang
- State Key Lab of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Zi Ye
- State Key Lab of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | - Jindong Zhao
- State Key Lab of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
- To whom correspondence should be addressed. E-mail:
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Zhang CC, Laurent S, Sakr S, Peng L, Bédu S. Heterocyst differentiation and pattern formation in cyanobacteria: a chorus of signals. Mol Microbiol 2006; 59:367-75. [PMID: 16390435 DOI: 10.1111/j.1365-2958.2005.04979.x] [Citation(s) in RCA: 205] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Heterocyst differentiation in filamentous cyanobacteria provides an excellent prokaryotic model for studying multicellular behaviour and pattern formation. In Anabaena sp. strain PCC 7120, for example, 5-10% of the cells along each filament are induced, when deprived of combined nitrogen, to differentiate into heterocysts. Heterocysts are specialized in the fixation of N(2) under oxic conditions and are semi-regularly spaced among vegetative cells. This developmental programme leads to spatial separation of oxygen-sensitive nitrogen fixation (by heterocysts) and oxygen-producing photosynthesis (by vegetative cells). The interdependence between these two cell types ensures filament growth under conditions of combined-nitrogen limitation. Multiple signals have recently been identified as necessary for the initiation of heterocyst differentiation, the formation of the heterocyst pattern and pattern maintenance. The Krebs cycle metabolite 2-oxoglutarate (2-OG) serves as a signal of nitrogen deprivation. Accumulation of a non-metabolizable analogue of 2-OG triggers the complex developmental process of heterocyst differentiation. Once heterocyst development has been initiated, interactions among the various components involved in heterocyst differentiation determine the developmental fate of each cell. The free calcium concentration is crucial to heterocyst differentiation. Lateral diffusion of the PatS peptide or a derivative of it from a developing cell may inhibit the differentiation of neighbouring cells. HetR, a protease showing DNA-binding activity, is crucial to heterocyst differentiation and appears to be the central processor of various early signals involved in the developmental process. How the various signalling pathways are integrated and used to control heterocyst differentiation processes is a challenging question that still remains to be elucidated.
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Affiliation(s)
- Cheng-Cai Zhang
- Laboratoire de Chimie Bactérienne, UPR9043-CNRS, Institut de Biologie Structurale et Microbiologie, 31, chemin Joseph Aiguier, 13402 Marseille cedex 20, France.
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Wang Y, Xu X. Regulation by hetC of genes required for heterocyst differentiation and cell division in Anabaena sp. strain PCC 7120. J Bacteriol 2006; 187:8489-93. [PMID: 16321953 PMCID: PMC1316993 DOI: 10.1128/jb.187.24.8489-8493.2005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Unlike those of the wild-type strain, proheterocysts of the Anabaena sp. strain PCC 7120 hetC strain keep dividing. ftsZ, the most critical cell division gene, is up-regulated in hetC proheterocysts. Heterocyst differentiation genes hglD, hglE, patB, nifB, and xisA are no longer expressed in the hetC mutant. hetC also regulates the expression of patA, a pattern formation gene.
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Affiliation(s)
- Yu Wang
- The State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, People's Republic of China
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