Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2020 Sep;60(9):738-745.
doi: 10.1002/jobm.202000266. Epub 2020 Jun 9.

Molecular circuit of heterocyst differentiation in cyanobacteria

Harish  1 , Kunal Seth  2
Affiliations
Review

Molecular circuit of heterocyst differentiation in cyanobacteria

Harish et al. J Basic Microbiol. 2020 Sep.

Abstract

Differentiation commitment is one of the most complex mechanisms to study in biological science. One of the model systems used for understanding differentiation complexity is heterocyst development in cyanobacteria. Cyanobacteria have the capability of biological nitrogen fixation due to highly differentiated heterocyst cells. Once the nitrogen deficiency signal is perceived by the cyanobacteria, few of its vegetative cells commit toward the development of heterocyst. Heterocyst provides a microoxic environment that is essential for the nitrogenase complex to fix the atmospheric dinitrogen. The entire process of development of heterocyst can be divided into different steps, such as (a) sensing signal and differentiation induction, (b) positional (pattern) determination of heterocyst in the filament, (c) formation of extracellular thick heterocyst-specific layers, and (d) assembly of nitrogen-fixing machinery. Many of the key regulators that are essential for heterocyst formation in these different steps have been identified. Recently, the role of small RNA and interruption DNA elements that influence the heterocyst formation and function has also been identified. In this review article, we have outlined the current understanding of the entire molecular circuit of heterocyst development in a simplistic way. This article focuses on explaining key concepts related to heterocyst development and discusses recent discoveries in this line.

Keywords: Anabaena; HetR; NtcA; cyanobacteria; heterocyst differentiation; nitrogen fixation; pattern formation.

PubMed Disclaimer

References

REFERENCES

    1. Zhang JY, Chen WL, Zhang CC. hetR and patS, two genes necessary for heterocyst pattern formation, are widespread in filamentous nonheterocyst-forming cyanobacteria. Microbiology. 2009;155:1418-26.
    1. Roumezi B, Xu X, Risoul V, Fan Y, Lebrun R, Latifi A. The Pkn22 kinase of Nostoc PCC 7120 is required for cell differentiation via the phosphorylation of HetR on a residue highly conserved in genomes of heterocyst-forming cyanobacteria. Front Microbiol. 2020;10:3140.
    1. Valladares A, Flores E, Herrero A. The heterocyst differentiation transcriptional regulator HetR of the filamentous cyanobacterium Anabaena forms tetramers and can be regulated by phosphorylation. Mol Microbiol. 2016;99:808-19.
    1. Videau P, Rivers OS, Hurd K, Ushijima B, Oshiro RT, Ende RJ, et al. The heterocyst regulatory protein HetP and its homologs modulate heterocyst commitment in Anabaena sp. strain PCC 7120. Proc Natl Acad Sci USA. 2016;113:E6984-92.
    1. Higa KC, Callahan SM. Ectopic expression of hetP can partially bypass the need for hetR in heterocyst differentiation by Anabaena sp. strain PCC 7120. Mol Microbiol. 2010;77:562-74.

LinkOut - more resources