Nitrogen is important for plant growth and development. Plants take up nitrogen from their environment in the form of nitrates or Ammonia and convert it into amino acids with the help of genes. The rate of nitrate assimilation can be changed by the changes in nitrogen levels. The expression of nitrate assimilation genes is regulated by these TFs.
The same holds true for Cyanidioschyzon merolae, a unicellular red alga, which is an excellent model of higher organisms to study. The mechanism for this under nitrogen-repleted +N condition is not clear, despite the fact that the TF called CmMYB1 is responsible for transcribing nitrate assimilation genes.
A team of researchers from Tokyo Institute of Technology and other institutions studied the mechanisms controlling the regulation of CmMYB1 in C. merolae under +N condition.
They first created strains with CmMYB1 knocked out and then transformed them with different truncated versions of CmMYB1. They identified a sequence of CmMYB1 between positions 311 and380 as the key region responsible for downregulating nitrate assimilating genes under +N condition. Increased transcript levels of these genes were found in the strain lacking the key region of CmMYB1 under +N condition. The negative domain of CmMYB1 was labeled as the new sequence.
The subcellular binding capacity of CmMYB1 was found to be controlled byND. Under +N condition, the binding capacity of CmMYB1 to promoter regions of nitrate assimilating genes was reduced by the help of ND.
The team decided to identify the proteins involved in the regulation of ND. They constructed an overexpressing strain and used mass spectrometry and immunoprecipitation to get a list of potential binding proteins. Through a yeast two- hybrid analysis, they identified a newProtein with an unknown function, named CmNDB1, which interacts with CmMYB1.
They discovered that deletion of CmNDB1 resulted in nuclear localization of CmMYB1 and reduced promoter binding capacity under +N condition. CmNDB1 deletion increases the transcription of nitrate assimilation genes.
BothND and CmNDB1 negatively control the activity of CmMYB1 under +N condition, as well as its binding to promoter regions of nitrate assimilating genes to downregulate their transcription. Professor Imamura says that the first study to reveal the mechanisms behind the regulation of nitrate assimilation genes under +N condition is ours. These innovative results can help with the advancement of research in this field.
The identification of the critical ND region of CmMYB1 and CmNDB1 helped to understand the regulation of nitrate assimilation in C. merolae. The regulation of nitrate assimilation in this red alga and in other photosynthetic organisms is something that needs to be better understood.
Researchers will gain an improved understanding of important functions and mechanisms in plants through the wealth of information this study provides.
More information: CmNDB1 and a specific domain of CmMYB1 negatively regulates CmMYB1- dependent transcription of nitrate assimilation genes under nitrogen-repleted condition in a unicellular red alga, Frontiers in Plant Science (2022). DOI: 10.3389/fpls.2022.821947 Journal information: Frontiers in Plant Science Citation: Discovering molecular 'team-work' underlying nitrate assimilation in a unicellular red alga (2022, March 11) retrieved 11 March 2022 from https://phys.org/news/2022-03-molecular-team-work-underlying-nitrate-assimilation.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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