HetR-Dependent and -Independent Expression of Heterocyst-Related Genes in an Anabaena Strain Overproducing the NtcA Transcription Factor

@article{OlmedoVerd2005HetRDependentA,
  title={HetR-Dependent and -Independent Expression of Heterocyst-Related Genes in an Anabaena Strain Overproducing the NtcA Transcription Factor},
  author={Elvira Olmedo-Verd and Enrique Flores and Antonia Herrero and Alicia M. Muro-Pastor},
  journal={Journal of Bacteriology},
  year={2005},
  volume={187},
  pages={1985 - 1991}
}
ABSTRACT Heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120 depends on both the global nitrogen control transcription factor NtcA and the cell differentiation regulatory protein HetR, with expression of ntcA and hetR being dependent on each other. In this study we constructed strains that constitutively express the ntcA gene leading to high levels of NtcA protein irrespective of the nitrogen source, and we analyzed the effects of such NtcA levels on heterocyst… 
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41 Citations
Background Citations
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Methods Citations
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41 Citations

Transcription Activation by NtcA and 2-Oxoglutarate of Three Genes Involved in Heterocyst Differentiation in the Cyanobacterium Anabaena sp. Strain PCC 7120

A stringent requirement of both NtcA and 2-Oxoglutarate was observed for the detection of open complexes and transcript production at the three investigated promoters, which support a key role for 2-oxoglUTarate in transcription activation in the developing heterocyst.

NrrA, a nitrogen‐responsive response regulator facilitates heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120

It is concluded that the nrrA gene, which encodes a response regulator of the OmpR family with a DNA‐binding domain, facilitates heterocyst development.

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

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.

Two Genes Encoding Protein Kinases of the HstK Family Are Involved in Synthesis of the Minor Heterocyst-Specific Glycolipid in the Cyanobacterium Anabaena sp. Strain PCC 7120

It is proposed that DevH, a putative transcription factor, coordinates the synthesis of both HGLs, while Pkn44/Pkn30 and the previously characterized PrpJ may represent two distinct regulatory pathways involved in the synthesisation of the minor HGL and the major HGL, respectively.

Hfq Is Required for Optimal Nitrate Assimilation in the Cyanobacterium Anabaena sp. Strain PCC 7120

The results indicate that the RNA chaperone Hfq is involved in the regulation of the nir operon, although the mechanism for this regulation is still unknown.

Functional Overlap of hetP and hetZ in Regulation of Heterocyst Differentiation in Anabaena sp. Strain PCC 7120

Evidence is presented for the functional overlap of hetP and hetZ and for the key role of the HetR-HetP/HetZ circuit in regulation of heterocyst differentiation.

FurC (PerR) from Anabaena sp. PCC7120: a versatile transcriptional regulator engaged in the regulatory network of heterocyst development and nitrogen fixation.

In this work, the transcriptome of a furC-overexpressing strain was compared with that of a wild-type strain under both standard and nitrogen deficiency conditions and revealed a new player in the complex regulatory network of heterocyst formation and nitrogen fixation.

The putative phosphatase All1758 is necessary for normal growth, cell size and synthesis of the minor heterocyst-specific glycolipid in the cyanobacterium Anabaena sp. strain PCC 7120.

Results suggest that the protein encoded by all1758 may represent a link between cell growth, division and regulation of the morphological differentiation of heterocysts.

The Heterocyst-Specific Small RNA NsiR1 Regulates the Commitment to Differentiation in Nostoc

This work describes the identification of a novel target for NsiR1, a small RNA encoded in multiple slightly divergent copies, and shows how different copies of “sibling” sRNAs regulate the expression of different targets involved in one of the few examples of a differentiation process in prokaryotes.

The putative phosphatase All 1758 is necessary for normal growth , cell size and synthesis of the minor heterocyst-specific glycolipid in the cyanobacterium Anabaena sp . strain PCC 7120

Results suggest that the protein encoded by all1758 may represent a link between cell growth, division and regulation of the morphological differentiation of heterocysts.

49 References

The hetC Gene Is a Direct Target of the NtcA Transcriptional Regulator in Cyanobacterial Heterocyst Development

Activation of expression of hetC during heterocyst development appears thus to be directly operated by NtcA, indicating that HetC is not an NTCA-dependent element required for hetR induction.

Mutual dependence of the expression of the cell differentiation regulatory protein HetR and the global nitrogen regulator NtcA during heterocyst development

A mutual dependency in the induction of the regulatory genes hetR and ntcA that takes place in response to nitrogen step‐down in Anabaena cells is indicated.

Anabaena sp. strain PCC 7120 ntcA gene required for growth on nitrate and heterocyst development

The Anabaena sp. strain PCC 7120 ntcA (bifA) gene encodes a sequence-specific DNA-binding protein, NtcA (BifA, VF1) that interacts with the upstream region of several genes, including glnA, xisA,…

Independent regulation of nifHDK operon transcription and DNA rearrangement during heterocyst differentiation in the cyanobacterium Anabaena sp. strain PCC 7120

It is shown that heterocyst-specific transcription and DNA rearrangement of the nifHDK operon are independent of one another, suggesting that the regulation of these events might be coupled.

Requirement of the regulatory protein NtcA for the expression of nitrogen assimilation and heterocyst development genes in the cyanobacterium Anabaena sp. PCC7120

Results showed that the ntcA gene product, NTCA, is required in Anabaena sp.

Transcriptional activation of NtcA-dependent promoters of Synechococcus sp. PCC 7942 by 2-oxoglutarate in vitro

It is proposed that the intracellular concentration of 2-oxoglutarate functions as a signaling molecule that transmits information on cellular nitrogen status to NtcA and thereby regulates the transcription of genes related to nitrogen assimilation in cyanobacteria.

In vivo activity of the nitrogen control transcription factor NtcA is subjected to metabolic regulation in Synechococcus sp. strain PCC 7942.

Results indicate in vivo regulation of the activity of NtcA at activation of transcription of nitrogen-regulated genes as a function of the nitrogen status of the cell.

Expression of the Anabaena sp. strain PCC 7120 xisA gene from a heterologous promoter results in excision of the nifD element

The xisA gene was shown to be the only Anabaena gene required for the proper rearrangement in E. coli of a plasmid containing the borders of the nifD element.

Characterization of devH, a Gene Encoding a Putative DNA Binding Protein Required for Heterocyst Function inAnabaena sp. Strain PCC 7120

Nitrogen starvation of the devH mutant induces heterocysts of wild-type morphology, but the mutant is inviable in the absence of fixed nitrogen and unable to reduce acetylene aerobically.

NtcA, a global nitrogen regulator from the cyanobacterium Synechococcus that belongs to the Crp family of bacterial regulators

The gene ntcA is proposed to encode a transcriptional activator of genes subject to nitrogen control in Synechococcus, and of special biological significance, is the presence of a conserved helix‐turn‐helix motif in the sequence close to the C‐terminal end of all the proteins in the family.