scholarly journals Exogenous Phytohormones Modulates Cypermethrin Stress in Anabaena sp. and Nostoc Muscorum: Toxicity Alleviation by Up-regulation of Ascorbate-glutathione Cycle

2021 ◽  
Author(s):  
Santwana Tiwari ◽  
Sheo Mohan Prasad
Keyword(s):  
Control Level ◽  
Cellular Membrane ◽  
Nostoc Muscorum ◽  
Monodehydroascorbate Reductase ◽  
Total Glutathione ◽  
Anabaena Sp ◽  
Glutathione Cycle ◽  
Pcc 7120 ◽  
Oxidative Biomarkers

Abstract Present study demonstrated the effect of phytohormones KN and IAA under cypermethrin (Cyp1; 2 µg ml− 1 and Cyp2; 4 µg ml− 1) toxicity in two nitrogen fixing cyanobacteria Nostoc muscorum ATCC 27893 and Anabaena sp. PCC 7120 by investigating growth, exopolysaccharides (EPS) contents, protein content, oxidative stress visualization inside the cell and ascorbate- glutathione cycle. Decline in growth were noticed under both the doses of cypermethrin but the decline was more (30%) at higher dose in Anabaena sp. PCC 7120 as compare to N. muscorum. This decrease was due to increased production of oxidative biomarkers (i.e. SOR and H2O2) subsequently membrane got damaged which was noticed by measuring MDA equivalents content (in vivo visualization). Kinetin and IAA alleviated the SOR and H2O2 content resulting in recovery of cellular membrane and the growth was optimized up to control level. Detoxification of H2O2 is guided by enzymes/metabolites of AsA-GSH cycle like ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorabte reductase (DHAR) activity were found to be stimulated at lower dose of cypermethrin as compare to higher dose. while the amount of metabolites: total ascorbate (AsA), total glutathione (GSH) and ratios of reduced/oxidized AsA (AsA/DHA) and GSH (GSH/GSSG) showed significant reduction at both the doses but the reduction was more at higher dose of cypermethrin. Kinetin and IAA positively regulate the AsA-GSH cycle by enhancing the activity of APX, GR, MDHAR and DHAR activity and raising the metabolites content and their reduced/oxidized ratio. This study suggests the increased enzymatic activity and AsA/DHA ratio leads to reduced production of H2O2 in the presence of both the phytohormones which further leads to enhanced growth in both the organism but the effect of KN and IAA was more pronounced in N. muscorum suggesting its resistivity against stress.

scholarly journals Biosensors-Based In Vivo Quantification of 2-Oxoglutarate in Cyanobacteria and Proteobacteria

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 51 ◽  
Author(s):  
Hai-Lin Chen ◽  
Amel Latifi ◽  
Cheng-Cai Zhang ◽  
Christophe Bernard
Keyword(s):  
Conformational Changes ◽  
Nitrogen Assimilation ◽  
Krebs Cycle ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Cellular Level ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

2-oxoglutarate (α-ketoglutarate; 2-OG) is an intermediate of the Krebs cycle, and constitutes the carbon skeleton for nitrogen assimilation and the synthesis of a variety of compounds. In addition to being an important metabolite, 2-OG is a signaling molecule with a broad regulatory repertoire in a variety of organisms, including plants, animals, and bacteria. Although challenging, measuring the levels and variations of metabolic signals in vivo is critical to better understand how cells control specific processes. To measure cellular 2-OG concentrations and dynamics, we designed a set of biosensors based on the fluorescence resonance energy transfer (FRET) technology that can be used in vivo in different organisms. For this purpose, we took advantage of the conformational changes of two cyanobacterial proteins induced by 2-OG binding. We show that these biosensors responded immediately and specifically to different 2-OG levels, and hence allowed to measure 2-OG variations in function of environmental modifications in the proteobacterium Escherichia coli and in the cyanobacterium Anabaena sp. PCC 7120. Our results pave the way to study 2-OG dynamics at the cellular level in uni- and multi-cellular organisms.

scholarly journals Site-Directed Mutagenesis of the Anabaena sp. Strain PCC 7120 Nitrogenase Active Site To Increase Photobiological Hydrogen Production

2010 ◽  
Vol 76 (20) ◽  
pp. 6741-6750 ◽  
Author(s):  
Hajime Masukawa ◽  
Kazuhito Inoue ◽  
Hidehiro Sakurai ◽  
C. Peter Wolk ◽  
Robert P. Hausinger
Keyword(s):  
Active Site ◽  
Electron Flow ◽  
Hydrogen Gas ◽  
Site Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Proton Reduction ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Iron Molybdenum Cofactor

ABSTRACT Cyanobacteria use sunlight and water to produce hydrogen gas (H2), which is potentially useful as a clean and renewable biofuel. Photobiological H2 arises primarily as an inevitable by-product of N2 fixation by nitrogenase, an oxygen-labile enzyme typically containing an iron-molybdenum cofactor (FeMo-co) active site. In Anabaena sp. strain 7120, the enzyme is localized to the microaerobic environment of heterocysts, a highly differentiated subset of the filamentous cells. In an effort to increase H2 production by this strain, six nitrogenase amino acid residues predicted to reside within 5 � of the FeMo-co were mutated in an attempt to direct electron flow selectively toward proton reduction in the presence of N2. Most of the 49 variants examined were deficient in N2-fixing growth and exhibited decreases in their in vivo rates of acetylene reduction. Of greater interest, several variants examined under an N2 atmosphere significantly increased their in vivo rates of H2 production, approximating rates equivalent to those under an Ar atmosphere, and accumulated high levels of H2 compared to the reference strains. These results demonstrate the feasibility of engineering cyanobacterial strains for enhanced photobiological production of H2 in an aerobic, nitrogen-containing environment.

scholarly journals Thioredoxin Dependent Changes in the Redox States of FurA from Anabaena sp. PCC 7120

Antioxidants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 913
Author(s):  
Jorge Guío ◽  
María Teresa Bes ◽  
Mónica Balsera ◽  
Laura Calvo-Begueria ◽  
Emma Sevilla ◽  
...  
Keyword(s):  
Reductase Activity ◽  
Thioredoxin Reductase ◽  
Zinc Ion ◽  
Exchange Reactions ◽  
Redox Partner ◽  
Redox Partners ◽  
Anabaena Sp ◽  
Pcc 7120

FurA is a multifunctional regulator in cyanobacteria that contains five cysteines, four of them arranged into two CXXC motifs. Lack of a structural zinc ion enables FurA to develop disulfide reductase activity. In vivo, FurA displays several redox isoforms, and the oxidation state of its cysteines determines its activity as regulator and its ability to bind different metabolites. Because of the relationship between FurA and the control of genes involved in oxidative stress defense and photosynthetic metabolism, we sought to investigate the role of type m thioredoxin TrxA as a potential redox partner mediating dithiol-disulfide exchange reactions necessary to facilitate the interaction of FurA with its different ligands. Both in vitro cross-linking assays and in vivo two-hybrid studies confirmed the interaction between FurA and TrxA. Light to dark transitions resulted in reversible oxidation of a fraction of the regulator present in Anabaena sp. PCC7120. Reconstitution of an electron transport chain using E. coli NADPH-thioredoxin-reductase followed by alkylation of FurA reduced cysteines evidenced the ability of TrxA to reduce FurA. Furthermore, the use of site-directed mutants allowed us to propose a plausible mechanism for FurA reduction. These results point to TrxA as one of the redox partners that modulates FurA performance.

scholarly journals ThetrpEGene Negatively Regulates Differentiation of Heterocysts at the Level of Induction in Anabaena sp. Strain PCC 7120

2014 ◽  
Vol 197 (2) ◽  
pp. 362-370 ◽  
Author(s):  
Patrick Videau ◽  
Loralyn M. Cozy ◽  
Jasmine E. Young ◽  
Blake Ushijima ◽  
Reid T. Oshiro ◽  
...  
Keyword(s):  
Repeat Sequence ◽  
Mutant Phenotype ◽  
Wild Type ◽  
Content Type ◽  
Type Pattern ◽  
In The Wild ◽  
Anabaena Sp ◽  
Pcc 7120

Levels of 2-oxoglutarate (2-OG) reflect nitrogen status in many bacteria. In heterocystous cyanobacteria, a spike in the 2-OG level occurs shortly after the removal of combined nitrogen from cultures and is an integral part of the induction of heterocyst differentiation. In this work, deletion of one of the two annotatedtrpEgenes inAnabaenasp. strain PCC 7120 resulted in a spike in the 2-OG level and subsequent differentiation of a wild-type pattern of heterocysts when filaments of the mutant were transferred from growth on ammonia to growth on nitrate. In contrast, 2-OG levels were unaffected in the wild type, which did not differentiate under the same conditions. An inverted-repeat sequence located upstream oftrpEbound a central regulator of differentiation, HetR,in vitroand was necessary for HetR-dependent transcription of a reporter fusion and complementation of the mutant phenotypein vivo. Functional complementation of the mutant phenotype with the addition of tryptophan suggested that levels of tryptophan, rather than the demonstrated anthranilate synthase activity of TrpE, mediated the developmental response of the wild type to nitrate. A model is presented for the observed increase in 2-OG in thetrpEmutant.

Cold-stress-altered phosphorylation of EF-Tu in the cyanobacterium Anabaena sp. strain PCC 7120

2007 ◽  
Vol 53 (5) ◽  
pp. 551-558 ◽  
Author(s):  
Bassam El-Fahmawi ◽  
George W. Owttrim
Keyword(s):  
Cold Stress ◽  
Prolonged Exposure ◽  
De Novo ◽  
Affinity Purification ◽  
Translation Elongation ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

Growth of prokaryotes at reduced temperature results in the formation of a cold-adapted ribosome through association with de novo synthesized polypeptides. In vitro and in vivo phosphorylation studies combined with affinity purification and mass spectrometry identified that the phosphorylation status of translation elongation factor EF-Tu was altered in response to cold stress in the photosynthetic, Gram-negative cyanobacterium Anabaena sp. strain PCC 7120. In response to a temperature downshift from 30 to 20 °C, EF-Tu was rapidly and transiently hyperphosphorylated during the acclimation phase followed by a reduction in phosphorylation below background levels in response to prolonged exposure. EF-Tu was identified as a phosphothreonine protein. Unexpectedly, ribosomal protein S2 was also observed to be a phosphoprotein continuously phosphorylated during cold stress. The phosphorylation status of EF-Tu has previously been associated with translational regulation in other systems, with a reduction in translation elongation occurring in response to phosphorylation. These results provide evidence for a novel mechanism by which translation is initially downregulated in response to cold stress in Anabaena.

scholarly journals Role of Two NtcA-Binding Sites in the Complex ntcA Gene Promoter of the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

2008 ◽  
Vol 190 (22) ◽  
pp. 7584-7590 ◽  
Author(s):  
Elvira Olmedo-Verd ◽  
Ana Valladares ◽  
Enrique Flores ◽  
Antonia Herrero ◽  
Alicia M. Muro-Pastor
Keyword(s):  
Binding Sites ◽  
Gene Promoter ◽  
Filamentous Cyanobacterium ◽  
Mobility Shift ◽  
Dnase I Footprinting ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

ABSTRACT Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that fixes N2 in specialized cells called heterocysts, which differentiate from vegetative cells in a process that requires the nitrogen control transcription factor NtcA. 2-Oxoglutarate-stimulated binding of purified NtcA to wild-type and modified versions of the ntcA gene promoter from Anabaena sp. was analyzed by mobility shift and DNase I footprinting assays, and the role of NtcA-binding sites in the expression of the ntcA gene during heterocyst differentiation was studied in vivo by using an ntcA-gfp translational fusion and primer extension analysis. Mutation of neither of the two identified NtcA-binding sites eliminated localized expression of ntcA in proheterocysts, but mutation of both sites led to very low, nonlocalized expression.

scholarly journals Specificities of and functional coordination between the two Cas6 maturation endonucleases in Anabaena sp. PCC 7120 assign orphan CRISPR arrays to three groups

2020 ◽  
Author(s):  
Viktoria Reimann ◽  
Marcus Ziemann ◽  
Hui Li ◽  
Tao Zhu ◽  
Juliane Behler ◽  
...  
Keyword(s):  
Translation System ◽  
Type I ◽  
Direct Repeats ◽  
Gene Cassettes ◽  
Mutant Strains ◽  
A Cell ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Cas Proteins

AbstractThe majority of bacteria and archaea possess an RNA-guided adaptive and inheritable immune system against viruses and other foreign genetic elements that consists of clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins. In most CRISPR-Cas systems, the maturation of CRISPR-derived small RNAs (crRNAs) is essential for functionality. In some bacteria, multiple instances of cas gene-free (orphan) repeat-spacer arrays exist, while additional instances of arrays that are linked to cas gene cassettes are present elsewhere in the genome.In the cyanobacterium Anabaena sp. PCC 7120, ten CRISPR-Cas repeat-spacer arrays are present, but only two cas gene cassettes plus a Tn7-associated eleventh array are observed. In this study, we deleted the two cas6 genes alr1482 (Type III-D) or alr1566 (Type I-D) and tested the specificities of the two corresponding enzymes in the resulting mutant strains, as recombinant proteins and in a cell-free transcription-translation system. The results assign the direct repeats (DRs) to three different groups. While Alr1566 is specific for one group, Alr1482 has a higher preference for the DRs of the second group but can also cleave those of the first group. We found that this cross-recognition limits crRNA accumulation for the Type I-D system in vivo.We also show that the DR of the cas gene-free CRISPR array of cyanophage N-1 is processed by these enzymes, suggesting that it is fully competent in association with host-encoded Cas proteins. The data support a strong tendency for array fragmentation in multicellular cyanobacteria and disfavor other possibilities, such as the nonfunctionality of these orphan repeat-spacer arrays. Our data demonstrate the functional coordination of Cas6 endonucleases with both neighboring and remote repeat-spacer arrays in the CRISPR-Cas system of cyanobacteria.

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