scholarly journals Inactivation of Three RG(S/T)GR Pentapeptide-Containing Negative Regulators of HetR Results in Lethal Differentiation of Anabaena PCC 7120

Life ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 326
Author(s):  
Ivan Khudyakov ◽  
Grigory Gladkov ◽  
Jeff Elhai
Keyword(s):  
Mutational Analysis ◽  
Filamentous Cyanobacterium ◽  
Intercellular Signaling ◽  
Tight Control ◽  
Negative Regulators ◽  
Short Peptide ◽  
Anabaena Pcc 7120 ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

The filamentous cyanobacterium Anabaena sp. PCC 7120 produces, during the differentiation of heterocysts, a short peptide PatS and a protein HetN, both containing an RGSGR pentapeptide essential for activity. Both act on the master regulator HetR to guide heterocyst pattern formation by controlling the binding of HetR to DNA and its turnover. A third small protein, PatX, with an RG(S/T)GR motif is present in all HetR-containing cyanobacteria. In a nitrogen-depleted medium, inactivation of patX does not produce a discernible change in phenotype, but its overexpression blocks heterocyst formation. Mutational analysis revealed that PatX is not required for normal intercellular signaling, but it nonetheless is required when PatS is absent to prevent rapid ectopic differentiation. Deprivation of all three negative regulators—PatS, PatX, and HetN—resulted in synchronous differentiation. However, in a nitrogen-containing medium, such deprivation leads to extensive fragmentation, cell lysis, and aberrant differentiation, while either PatX or PatS as the sole HetR regulator can establish and maintain a semiregular heterocyst pattern. These results suggest that tight control over HetR by PatS and PatX is needed to sustain vegetative growth and regulated development. The mutational analysis has been interpreted in light of the opposing roles of negative regulators of HetR and the positive regulator HetL.

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.

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

2009 ◽  
Vol 192 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Masakazu Toyoshima ◽  
Naobumi V. Sasaki ◽  
Makoto Fujiwara ◽  
Shigeki Ehira ◽  
Masayuki Ohmori ◽  
...  
Keyword(s):  
Filamentous Cyanobacterium ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

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

Microbiology ◽  
2003 ◽  
Vol 149 (11) ◽  
pp. 3257-3263 ◽  
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.

Function analysis of RNase E in the filamentous cyanobacterium Anabaena sp. PCC 7120

2020 ◽  
Vol 171 (5-6) ◽  
pp. 194-202
Author(s):  
Huaduo Yan ◽  
Yarui Cheng ◽  
Li Wang ◽  
Wenli Chen
Keyword(s):  
Function Analysis ◽  
Filamentous Cyanobacterium ◽  
Rnase E ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

Characterization and responses to environmental cues of a photosynthetic antenna-deficient mutant of the filamentous cyanobacterium Anabaena sp. PCC 7120

2014 ◽  
Vol 171 (11) ◽  
pp. 915-926 ◽  
Author(s):  
Francisco Leganés ◽  
Francisco Martínez-Granero ◽  
M. Ángeles Muñoz-Martín ◽  
Eduardo Marco ◽  
Alberto Jorge ◽  
...  
Keyword(s):  
Environmental Cues ◽  
Filamentous Cyanobacterium ◽  
Deficient Mutant ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Photosynthetic Antenna
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