scholarly journals The Cyanotoxin BMAA Induces Heterocyst Specific Gene Expression in Anabaena sp. PCC 7120 under Repressive Conditions

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 478 ◽  
Author(s):  
Alexandra Popova ◽  
Tatiana Semashko ◽  
Natalia Kostina ◽  
Ulla Rasmussen ◽  
Vadim Govorun ◽  
...  
Keyword(s):  
Quantitative Polymerase Chain Reaction ◽  
Specific Gene ◽  
Filamentous Cyanobacteria ◽  
Protein Amino Acid ◽  
Vegetative Cells ◽  
Differentiated Cells ◽  
Anabaena Sp ◽  
Polymerase Chain ◽  
Pcc 7120 ◽  
Diazotrophic Growth

Cyanobacteria synthesize neurotoxic β-N-methylamino-l-alanine (BMAA). The roles of this non-protein amino acid in cyanobacterial cells are insufficiently studied. During diazotrophic growth, filamentous cyanobacteria form single differentiated cells, called heterocysts, which are separated by approximately 12–15 vegetative cells. When combined nitrogen is available, heterocyst formation is blocked and cyanobacterial filaments contain only vegetative cells. In the present study, we discovered that exogenous BMAA induces the process of heterocyst formation in filamentous cyanobacteria under nitrogen-replete conditions that normally repress cell differentiation. BMAA treated cyanobacteria form heterocyst-like dark non-fluorescent non-functional cells. It was found that glutamate eliminates the BMAA mediated derepression. Quantitative polymerase chain reaction (qPCR) permitted to detect the BMAA impact on the transcriptional activity of several genes that are implicated in nitrogen assimilation and heterocyst formation in Anabaena sp. PCC 7120. We demonstrated that the expression of several essential genes increases in the BMAA presence under repressive conditions.

scholarly journals Inactivation of a Heterocyst-Specific Invertase Indicates a Principal Role of Sucrose Catabolism in Heterocysts of Anabaena sp.

2010 ◽  
Vol 192 (20) ◽  
pp. 5526-5533 ◽  
Author(s):  
Rocío López-Igual ◽  
Enrique Flores ◽  
Antonia Herrero
Keyword(s):  
Fluorescent Protein ◽  
Northern Analysis ◽  
Filamentous Cyanobacterium ◽  
Nitrogen Deprivation ◽  
Vegetative Cells ◽  
Anabaena Sp ◽  
Green Fluorescent ◽  
Pcc 7120 ◽  
Diazotrophic Growth

ABSTRACT Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that carries out N2 fixation in specialized cells called heterocysts, which exchange nutrients and regulators with the filament's vegetative cells that perform the photosynthetic fixation of CO2. The Anabaena genome carries two genes coding for alkaline/neutral invertases, invA and invB. As shown by Northern analysis, both genes were expressed monocistronically and induced under nitrogen deprivation, although induction was stronger for invB than for invA. Whereas expression of an InvA-N-GFP fusion (green fluorescent protein [GFP] fused to the N terminus of the InvA protein [InvA-N]) was homogeneous along the cyanobacterial filament, consistent with the lack of dependence on HetR, expression of an InvB-N-GFP fusion upon combined nitrogen deprivation took place mainly in differentiating and mature heterocysts. In an hetR genetic background, the InvB-N-GFP fusion was strongly expressed all along the filament. An insertional mutant of invA could grow diazotrophically but was impaired in nifHDK induction and exhibited an increased frequency of heterocysts, suggesting a regulatory role of the invertase-mediated carbon flux in vegetative cells. In contrast, an invB mutant was strongly impaired in diazotrophic growth, showing a crucial role of sucrose catabolism mediated by the InvB invertase in the heterocysts.

scholarly journals Expression of Shewanella oneidensis MR-1 [FeFe]-Hydrogenase Genes in Anabaena sp. Strain PCC 7120

2012 ◽  
Vol 78 (24) ◽  
pp. 8579-8586 ◽  
Author(s):  
Katrin Gärtner ◽  
Sigal Lechno-Yossef ◽  
Adam J. Cornish ◽  
C. Peter Wolk ◽  
Eric L. Hegg
Keyword(s):  
Renewable Resources ◽  
Shewanella Oneidensis ◽  
Specific Requirement ◽  
Filamentous Cyanobacteria ◽  
Content Type ◽  
Differentiated Cells ◽  
Anabaena Sp ◽  
Pcc 7120

ABSTRACTH2generated from renewable resources holds promise as an environmentally innocuous fuel that releases only energy and water when consumed. In biotechnology, photoautotrophic oxygenic diazotrophs could produce H2from water and sunlight using the cells' endogenous nitrogenases. However, nitrogenases have low turnover numbers and require large amounts of ATP. [FeFe]-hydrogenases found in other organisms can have 1,000-fold higher turnover numbers and no specific requirement for ATP but are very O2sensitive. Certain filamentous cyanobacteria protect nitrogenase from O2by sequestering the enzyme within internally micro-oxic, differentiated cells called heterocysts. We heterologously expressed the [FeFe]-hydrogenase operon fromShewanella oneidensisMR-1 inAnabaenasp. strain PCC 7120 using the heterocyst-specific promoter PhetN. Active [FeFe]-hydrogenase was detected in and could be purified from aerobically grownAnabaenasp. strain PCC 7120, but only when the organism was grown under nitrate-depleted conditions that elicited heterocyst formation. These results suggest that the heterocysts protected the [FeFe]-hydrogenase against inactivation by O2.

Disruption of the Gene trx-m1 Impedes the Growth of Anabaena sp. PCC 7120 under Nitrogen Starvation

2019 ◽  
Vol 60 (7) ◽  
pp. 1504-1513 ◽  
Author(s):  
Fr�d�ric Deschoenmaeker ◽  
Shoko Mihara ◽  
Tatsuya Niwa ◽  
Hideki Taguchi ◽  
Jiro Nomata ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Cellular Structure ◽  
Nitrogen Starvation ◽  
Nitrogen Response ◽  
Regulation Network ◽  
Anabaena Sp ◽  
Thiol Redox ◽  
Weak Expression ◽  
Pcc 7120 ◽  
Diazotrophic Growth

Abstract Cyanobacteria possess a sophisticated photosynthesis-based metabolism with admirable plasticity. This plasticity is possible via the deep regulation network, the thiol-redox regulations operated by thioredoxin (hereafter, Trx). In this context, we characterized the Trx-m1-deficient mutant strain of Anabaena sp., PCC 7120 (shortly named A.7120), cultivated under nitrogen limitation. Trx-m1 appears to coordinate the nitrogen response and its absence induces large changes in the proteome. Our data clearly indicate that Trx-m1 is crucial for the diazotrophic growth of A.7120. The lack of Trx-m1 resulted in a large differentiation of heterocysts (>20% of total cells), which were barely functional probably due to a weak expression of nitrogenase. In addition, heterocysts of the mutant strain did not display the usual cellular structure of nitrogen-fixative cells. This unveiled why the mutant strain was not able to grow under nitrogen starvation.

scholarly journals Novel DNA-Binding Proteins in the Cyanobacterium Anabaena sp. Strain PCC 7120

2002 ◽  
Vol 184 (14) ◽  
pp. 3931-3940 ◽  
Author(s):  
Olga A. Koksharova ◽  
C. Peter Wolk
Keyword(s):  
Dna Binding ◽  
Insertional Mutagenesis ◽  
Binding Proteins ◽  
Dna Binding Proteins ◽  
Vegetative Cells ◽  
Heterocyst Differentiation ◽  
The Third ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

ABSTRACT As an approach towards elucidation of the biochemical regulation of the progression of heterocyst differentiation in Anabaena sp. strain PCC 7120, we have identified proteins that bind to a 150-bp sequence upstream from hepC, a gene that plays a role in the synthesis of heterocyst envelope polysaccharide. Such proteins were purified in four steps from extracts of vegetative cells of Anabaena sp. Two of these proteins (Abp1 and Abp2) are encoded by neighboring genes in the Anabaena sp. chromosome. The genes that encode the third (Abp3) and fourth (Abp4) proteins are situated at two other loci in that chromosome. Insertional mutagenesis of abp2 and abp3 blocked expression of hepC and hepA and prevented heterocyst maturation and aerobic fixation of N2.

scholarly journals Thioredoxin targets are regulated in heterocysts of cyanobacterium Anabaena sp. PCC 7120 in a light-independent manner

2019 ◽  
Vol 71 (6) ◽  
pp. 2018-2027
Author(s):  
Shoko Mihara ◽  
Kazunori Sugiura ◽  
Keisuke Yoshida ◽  
Toru Hisabori
Keyword(s):  
Redox Regulation ◽  
Regulation System ◽  
Regulation Mechanism ◽  
Light Conditions ◽  
Nitrogen Fixing ◽  
Vegetative Cells ◽  
Target Proteins ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

Abstract In the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, glucose 6-phosphate dehydrogenase (G6PDH) plays an important role in producing the power for reducing nitrogenase under light conditions. Our previous study showed that thioredoxin suppresses G6PDH by reducing its activator protein OpcA, implying that G6PDH is inactivated under light conditions because thioredoxins are reduced by the photosynthetic electron transport system in cyanobacteria. To address how Anabaena sp. PCC 7120 maintains G6PDH activity even under light conditions when nitrogen fixation occurs, we investigated the redox regulation system in vegetative cells and specific nitrogen-fixing cells named heterocysts, individually. We found that thioredoxin target proteins were more oxidized in heterocysts than in vegetative cells under light conditions. Alterations in the redox regulation mechanism of heterocysts may affect the redox states of thioredoxin target proteins, including OpcA, so that G6PDH is activated in heterocysts even under light conditions.

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