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

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.

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The Ser/Thr Kinase PknH Is Essential for Maintaining Heterocyst Pattern in the Cyanobacterium Anabaena sp. Strain PCC 7120

Life ◽

10.3390/life8030034 ◽

2018 ◽

Vol 8 (3) ◽

pp. 34 ◽

Cited By ~ 6

Author(s):

Shun-ichi Fukushima ◽

Shigeki Ehira

Keyword(s):

Pattern Formation ◽

Lateral Inhibition ◽

Time Lapse ◽

Filamentous Cyanobacterium ◽

Nitrogen Deprivation ◽

Heterocyst Differentiation ◽

Cyanobacterium Anabaena ◽

Reporter Strains ◽

Anabaena Sp ◽

Pcc 7120

In the filamentous cyanobacterium Anabaena sp. strain, PCC 7120, heterocysts (which are nitrogen-fixing cells) are formed in the absence of combined nitrogen in the medium. Heterocysts are separated from one another by 10 to 15 vegetative cells along the filaments, which consist of a few hundred of cells. hetR is necessary for heterocyst differentiation; and patS and hetN, expressed in heterocysts, play important roles in heterocyst pattern formation by laterally inhibiting the expression of hetR in adjacent cells. The results of this study indicated that pknH, which encodes a Ser/Thr kinase, was also involved in heterocyst pattern formation. In the pknH mutant, the heterocyst pattern was normal within 24 h after nitrogen deprivation, but multiple contiguous heterocysts were formed from 24 to 48 h. A time-lapse analysis of reporter strains harboring a fusion between gfp and the hetR promoter indicated that pknH was required to suppress hetR expression in cells adjacent to the preexisting heterocysts. These results indicated that pknH was necessary for the lateral inhibition of heterocyst differentiation to maintain the heterocyst pattern.

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Inactivation of patS and hetN causes lethal levels of heterocyst differentiation in the filamentous cyanobacterium Anabaena sp. PCC 7120

Molecular Microbiology ◽

10.1111/j.1365-2958.2005.04678.x ◽

2005 ◽

Vol 57 (1) ◽

pp. 111-123 ◽

Cited By ~ 55

Author(s):

Pritty B. Borthakur ◽

Christine C. Orozco ◽

Shirley S. Young-Robbins ◽

Robert Haselkorn ◽

Sean M. Callahan

Keyword(s):

Filamentous Cyanobacterium ◽

Heterocyst Differentiation ◽

Cyanobacterium Anabaena ◽

Anabaena Sp ◽

Pcc 7120

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Regulation of Genes Involved in Heterocyst Differentiation in the Cyanobacterium Anabaena sp. Strain PCC 7120 by a Group 2 Sigma Factor SigC

Life ◽

10.3390/life5010587 ◽

2015 ◽

Vol 5 (1) ◽

pp. 587-603 ◽

Cited By ~ 6

Author(s):

Shigeki Ehira ◽

Shogo Miyazaki

Keyword(s):

Sigma Factor ◽

Heterocyst Differentiation ◽

Cyanobacterium Anabaena ◽

Anabaena Sp ◽

Group 2 ◽

Pcc 7120

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

Journal of Bacteriology ◽

10.1128/jb.184.14.3931-3940.2002 ◽

2002 ◽

Vol 184 (14) ◽

pp. 3931-3940 ◽

Cited By ~ 26

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.

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Early candidacy for differentiation into heterocysts in the filamentous cyanobacterium Anabaena sp. PCC 7120

Archives of Microbiology ◽

10.1007/s00203-009-0525-4 ◽

2009 ◽

Vol 192 (1) ◽

pp. 23-31 ◽

Cited By ~ 18

Author(s):

Masakazu Toyoshima ◽

Naobumi V. Sasaki ◽

Makoto Fujiwara ◽

Shigeki Ehira ◽

Masayuki Ohmori ◽

...

Keyword(s):

Filamentous Cyanobacterium ◽

Cyanobacterium Anabaena ◽

Anabaena Sp ◽

Pcc 7120

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An increase in the level of 2-oxoglutarate promotes heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120

Microbiology ◽

10.1099/mic.0.26462-0 ◽

2003 ◽

Vol 149 (11) ◽

pp. 3257-3263 ◽

Cited By ~ 43

Author(s):

Jian-Hong Li ◽

Sophie Laurent ◽

Viren Konde ◽

Sylvie Bédu ◽

Cheng-Cai Zhang

Keyword(s):

Inorganic Nitrogen ◽

Cell Types ◽

Filamentous Cyanobacterium ◽

Nitrogen Status ◽

Gene Encoding ◽

Combined Nitrogen ◽

Cyanobacterium Anabaena ◽

Anabaena Sp ◽

Pcc 7120 ◽

Heterocyst Development

In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, a starvation of combined nitrogen induces differentiation of heterocysts, cells specialized in nitrogen fixation. How do filaments perceive the limitation of the source of combined nitrogen, and what determines the proportion of heterocysts? In cyanobacteria, 2-oxoglutarate provides a carbon skeleton for the incorporation of inorganic nitrogen. Recently, it has been proposed that the concentration of 2-oxoglutarate reflects the nitrogen status in cyanobacteria. To investigate the effect of 2-oxoglutarate on heterocyst development, a heterologous gene encoding a 2-oxoglutarate permease under the control of a regulated promoter was expressed in Anabaena sp. PCC 7120. The increase of 2-oxoglutarate within cells can trigger heterocyst differentiation in a subpopulation of filaments even in the presence of nitrate. In the absence of a source of combined nitrogen, it can increase heterocyst frequency, advance the timing of commitment to heterocyst development and further increase the proportion of heterocysts in a patS mutant. Here, it is proposed that the intracellular concentration of 2-oxoglutarate is involved in the determination of the proportion of the two cell types according to the carbon/nitrogen status of the filament.

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c-di-GMP Homeostasis Is Critical for Heterocyst Development in Anabaena sp. PCC 7120

Frontiers in Microbiology ◽

10.3389/fmicb.2021.793336 ◽

2021 ◽

Vol 12 ◽

Author(s):

Min Huang ◽

Ju-Yuan Zhang ◽

Xiaoli Zeng ◽

Cheng-Cai Zhang

Keyword(s):

Nitrogen Starvation ◽

Filamentous Cyanobacterium ◽

Nitrogen Deprivation ◽

Heterocyst Differentiation ◽

Combined Nitrogen ◽

Heterocyst Frequency ◽

Genes Encoding ◽

Anabaena Sp ◽

Opposing Effects ◽

Pcc 7120

c-di-GMP is a ubiquitous bacterial signal regulating various physiological process. Anabaena PCC 7120 (Anabaena) is a filamentous cyanobacterium able to form regularly-spaced heterocysts for nitrogen fixation, in response to combined-nitrogen deprivation in 24h. Anabaena possesses 16 genes encoding proteins for c-di-GMP metabolism, and their functions are poorly characterized, except all2874 (cdgS) whose deletion causes a decrease in heterocyst frequency 48h after nitrogen starvation. We demonstrated here that c-di-GMP levels increased significantly in Anabaena after combined-nitrogen starvation. By inactivating each of the 16 genes, we found that the deletion of all1175 (cdgSH) led to an increase of heterocyst frequency 24h after nitrogen stepdown. A double mutant ΔcdgSHΔcdgS had an additive effect over the single mutants in regulating heterocyst frequency, indicating that the two genes acted at different time points for heterocyst spacing. Biochemical and genetic data further showed that the functions of CdgSH and CdgS in the setup or maintenance of heterocyst frequency depended on their opposing effects on the intracellular levels of c-di-GMP. Finally, we demonstrated that heterocyst differentiation was completely inhibited when c-di-GMP levels became too high or too low. Together, these results indicate that the homeostasis of c-di-GMP level is important for heterocyst differentiation in Anabaena.

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