Part:BBa_K4998032

HetR gene

Usage and Biology

This part is the coding region of the hetR protein gene. hetR is a serine-type protease that functions as a transcriptional factor and master regulator of heterocyst differentiation in filamentous, nitrogen-fixing cyanobacteria. Heterocysts are differentiated cells within the cyanobacterial filament that are capable of fixing atmospheric nitrogen, under diazotrophic conditions. [1, 2]

Naturally, heterocyst formation is triggered by the atmospheric nitrogen-carbon balance, which is reflected by the presence of 2-oxo-glutarate. When 2-OG is accumulated, it facilitates binding of the NtcA transcription factor, which is a cAMP receptor protein, to multiple DNA regulatory areas, so that it induces the production of multiple molecules, including the hetR. [1] The hetR forms dimeric and tetrameric structures and upregulates the transcription of several genes that promote heterocyst differentiation, as well as it upregulates the production of itself. It has been shown that hetR dimers and tetramers’ regulation is also achieved via phosphorylation. [1, 3]

HetR transcriptional factor is the master heterocyst formation regulator, since its presence is essential for the procedure to be done, while it has been proved that hetR overexpression induces the formation of more heterocysts per filament, even under repressive conditions. [1, 4] HetR is a 299-amino acid protein. It forms dimers consisting of two subunits that contain three domains, the N-terminal DBD, the middle flap domain and the C-terminal hood domain. [4] We use this part for the promotion of heterocyst formation within the Nostoc oryzae TAU-MAC 2710 strain filaments.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

References

[1] Zhou, R., Wei, X., Jiang, N., Li, H., Dong, Y., Hsi, K.-L., & Zhao, J. (1998). Evidence that Hetr protein is an unusual serine-type protease. Proceedings of the National Academy of Sciences, 95(9), 4959–4963. https://doi.org/10.1073/pnas.95.9.4959

[2] Zeng, X., & Zhang, C.-C. (2022). The making of a heterocyst in cyanobacteria. Annual Review of Microbiology, 76(1), 597–618. https://doi.org/10.1146/annurev-micro-041320-093442

[3] Chaurasia, A. K., & Apte, S. K. (2011). Improved eco-friendly recombinant Anabaena SP.. strain PCC7120 with enhanced nitrogen biofertilizer potential. Applied and Environmental Microbiology, 77(2), 395–399. https://doi.org/10.1128/aem.01714-10

[4] Hu, H.-X., Jiang, Y.-L., Zhao, M.-X., Cai, K., Liu, S., Wen, B., Lv, P., Zhang, Y., Peng, J., Zhong, H., Yu, H.-M., Ren, Y.-M., Zhang, Z., Tian, C., Wu, Q., Oliveberg, M., Zhang, C.-C., Chen, Y., & Zhou, C.-Z. (2015). Structural insights into HetR−PATs interaction involved in cyanobacterial pattern formation. Scientific Reports, 5(1). https://doi.org/10.1038/srep16470