scholarly journals Developmental Regulation of the Cell Division Protein FtsZ in Anabaena sp. Strain PCC 7120, a Cyanobacterium Capable of Terminal Differentiation

2000 ◽  
Vol 182 (16) ◽  
pp. 4640-4643 ◽  
Author(s):  
Isabelle Kuhn ◽  
Ling Peng ◽  
Sylvie Bedu ◽  
Cheng-Cai Zhang
Keyword(s):  
Nitrogen Fixation ◽  
Cell Division ◽  
Developmental Regulation ◽  
Terminal Differentiation ◽  
Filamentous Cyanobacterium ◽  
Differentiated Cells ◽  
Rational Explanation ◽  
Anabaena Sp ◽  
Cell Division Protein ◽  
Pcc 7120

ABSTRACT Heterocysts are terminally differentiated cells devoted to nitrogen fixation in the filamentous cyanobacterium Anabaena sp. strain PCC 7120. We show here that the cell division protein FtsZ is present in vegetative cells but undetectable in heterocysts. These results provide a first rational explanation for the inability of mature heterocysts to undergo cell division.

scholarly journals Anabaena sp. Strain PCC 7120 Gene devH Is Required for Synthesis of the Heterocyst Glycolipid Layer

2005 ◽  
Vol 187 (7) ◽  
pp. 2326-2331 ◽  
Author(s):  
Martha E. Ramírez ◽  
Pratibha B. Hebbar ◽  
Ruanbao Zhou ◽  
C. Peter Wolk ◽  
Stephanie E. Curtis
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Regulatory Protein ◽  
Protein A ◽  
Filamentous Cyanobacterium ◽  
Fixed Nitrogen ◽  
Ultrastructural Studies ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Mutant Forms

ABSTRACT In response to deprivation for fixed nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 provides a microoxic intracellular environment for nitrogen fixation through the differentiation of semiregularly spaced vegetative cells into specialized cells called heterocysts. The devH gene is induced during heterocyst development and encodes a product with characteristics of a trans-acting regulatory protein. A devH mutant forms morphologically distinguishable heterocysts but is Fox−, incapable of nitrogen fixation in the presence of oxygen. We demonstrate that rearrangements of nitrogen fixation genes take place normally in the devH mutant and that it is Fix+, i.e., has nitrogenase activity under anoxic conditions. The Fox− phenotype was shown by ultrastructural studies to be associated with the absence of the glycolipid layer of the heterocyst envelope. The expression of glycolipid biosynthetic genes in the mutant is greatly reduced, and heterocyst glycolipids are undetectable.

scholarly journals Heterocyst-Specific Expression of patB, a Gene Required for Nitrogen Fixation in Anabaena sp. Strain PCC 7120

2003 ◽  
Vol 185 (7) ◽  
pp. 2306-2314 ◽  
Author(s):  
Kathryn M. Jones ◽  
William J. Buikema ◽  
Robert Haselkorn
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Removal ◽  
Deletion Mutant ◽  
Filamentous Cyanobacterium ◽  
Specific Expression ◽  
Growth And Survival ◽  
Combined Nitrogen ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Initial Pattern

ABSTRACT The patB gene product is required for growth and survival of the filamentous cyanobacterium Anabaena sp. strain PCC 7120 in the absence of combined nitrogen. A patB::gfp fusion demonstrated that this gene is expressed exclusively in heterocysts. patB mutants have a normal initial pattern of heterocyst spacing along the filament but differentiate excess heterocysts after several days in the absence of combined nitrogen. Expression of hetR and patS, two critical regulators of the heterocyst development cascade, are normal for patB mutants, indicating that patB acts downstream of them in the differentiation pathway. A patB deletion mutant suffers an almost complete cessation of growth and nitrogen fixation within 24 h of combined nitrogen removal. In contrast, a new PatB mutant that is defective in its N-terminal ferredoxin domain, or a previously described mutant that has a frameshift removing its C-terminal helix-turn-helix domain, grows very slowly and differentiates multiple contiguous heterocysts under nitrogen-deficient conditions.

scholarly journals The CRP-family transcriptional regulator DevH regulates expression of heterocyst-specific genes at the later stage of differentiation in the cyanobacterium Anabaena sp. strain PCC 7120

2020 ◽  
Author(s):  
Yohei Kurio ◽  
Yosuke Koike ◽  
Yu Kanesaki ◽  
Satoru Watanabe ◽  
Shigeki Ehira
Keyword(s):  
Nitrogen Fixation ◽  
Gene Cluster ◽  
Transcriptional Regulator ◽  
Heterocyst Differentiation ◽  
Differentiated Cells ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Oxygen Evolving ◽  
Pcc 7120 ◽  
Polysaccharide Layer

SummaryHeterocysts are terminally differentiated cells of filamentous cyanobacteria, which are specialized for nitrogen fixation. Because nitrogenase, an enzyme for nitrogen fixation, is easily inactivated by oxygen, the intracellular environment of heterocysts is kept microoxic. In heterocysts, the oxygen-evolving photosystem II is inactivated, a heterocyst-specific envelope with an outer polysaccharide layer and an inner glycolipid layer is formed to limit oxygen entry, and oxygen consumption is activated. Heterocyst differentiation, which is accompanied by drastic morphological and physiological changes, requires strictly controlled gene expression systems. Here, we investigated the functions of a CRP-family transcriptional regulator, DevH, in the process of heterocyst differentiation. A devH-knockdown strain, devHKD, was created by replacing the original promoter with the gifA promoter, which is repressed during heterocyst differentiation. Although devHKD formed morphologically distinct cells with the heterocyst envelope polysaccharide layer, it was unable to grow diazotrophically. Genes involved in construction of the microoxic environment, such as cox operons and the hgl island, were not upregulated in devHKD. Moreover, expression of the nif gene cluster was completely abolished. Even under anaerobic conditions, the nif gene cluster was not induced in devHKD. Thus, DevH is necessary for the establishment of a microoxic environment and induction of nitrogenase in heterocysts.

scholarly journals Transcriptional Regulation of the Heterocyst Patterning Gene patA from Anabaena sp. Strain PCC 7120

2010 ◽  
Vol 192 (18) ◽  
pp. 4732-4740 ◽  
Author(s):  
Shirley S. Young-Robbins ◽  
Douglas D. Risser ◽  
Jennifer R. Moran ◽  
Robert Haselkorn ◽  
Sean M. Callahan
Keyword(s):  
Cell Division ◽  
Periodic Pattern ◽  
Filamentous Cyanobacterium ◽  
Nitrogen Deprivation ◽  
Translational Start Site ◽  
Terminal Domain ◽  
Anabaena Sp ◽  
Altered Cell ◽  
Translational Start ◽  
Pcc 7120

ABSTRACT The filamentous cyanobacterium Anabaena sp. strain PCC 7120 forms a periodic pattern of nitrogen-fixing heterocysts when grown in the absence of combined nitrogen. PatA is necessary for proper patterning of heterocysts along filaments. In this study, apparent transcriptional start points (tsps) were identified at nucleotides −305, −614, and −645 relative to the translational start site (−305, −614, and −645 tsps). Transcriptional reporter fusions were used to show that transcription from the −305 tsp was induced in all cells of filaments in response to nitrogen deprivation, required hetR for induction, and increased in a patA mutant. Transcription from −614/−645 tsp reporter fusions was spatially regulated and occurred primarily in cells that would become heterocysts. Complementation of a patA mutant strain by alleles encoding substitutions in, or deletion of, the putative phosphoacceptor C-terminal domain indicates that the PATAN domain can function independently of the C-terminal domain of PatA. Localization of a ring of PatA-GFP at sites of cell division, as well as the formation of enlarged cells with altered cell morphology when patA was overexpressed, suggests that PatA may participate in cell division.

scholarly journals Manipulation of Pattern of Cell Differentiation in a hetR Mutant of Anabaena sp. PCC 7120 by Overexpressing hetZ Alone or with hetP

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 60 ◽  
Author(s):  
He Zhang ◽  
Xudong Xu
Keyword(s):  
Cell Differentiation ◽  
Peptide Inhibitor ◽  
Filamentous Cyanobacterium ◽  
Heterocyst Differentiation ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

In the filamentous cyanobacterium, Anabaena sp. PCC 7120, single heterocysts differentiate at semi-regular intervals in response to nitrogen stepdown. HetR is a principal regulator of heterocyst differentiation, and hetP and hetZ are two genes that are regulated directly by HetR. In a hetR mutant generated from the IHB (Institute of Hydrobiology) substrain of PCC 7120, heterocyst formation can be restored by moderate expression of hetZ and hetP. The resulting heterocysts are located at terminal positions. We used a tandem promoter, PrbcLPpetE, to express hetZ and hetP strongly in the hetR mutant. Co-expression of hetZ and hetP enabled the hetR mutant to form multiple contiguous heterocysts at both terminal and intercalary positions. Expression of hetZ, alone resulted in terminally located heterocysts, whereas expression of hetP, alone produced enlarged cells in strings. In the absence of HetR, formation of heterocysts was insensitive to the peptide inhibitor, RGSGR.

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.

scholarly journals Anabaena sp. Strain PCC 7120 hetY Gene Influences Heterocyst Development

2003 ◽  
Vol 185 (23) ◽  
pp. 6995-7000 ◽  
Author(s):  
Ho-Sung Yoon ◽  
Martin H. Lee ◽  
Jin Xiong ◽  
James W. Golden
Keyword(s):  
Atp Binding ◽  
Binding Motif ◽  
Filamentous Cyanobacterium ◽  
Hypothetical Proteins ◽  
Nitrogen Fixing ◽  
Fixed Nitrogen ◽  
Anabaena Sp ◽  
Time Required ◽  
Pcc 7120 ◽  
Heterocyst Development

ABSTRACT The filamentous cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120 responds to starvation for fixed nitrogen by producing a semiregular pattern of nitrogen-fixing cells called heterocysts. Overexpression of the hetY gene partially suppressed heterocyst formation, resulting in an abnormal heterocyst pattern. Inactivation of hetY increased the time required for heterocyst maturation and caused defects in heterocyst morphology. The 489-bp hetY gene (alr2300), which is adjacent to patS (asl2301), encodes a protein that belongs to a conserved family of bacterial hypothetical proteins that contain an ATP-binding motif.

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