ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Metabolism and Chemodiversity
This article is part of the Research TopicRegulation and Sensing of Amino Acid Metabolism in PlantsView all 3 articles
Loss of Arabidopsis ACR11 Results in Altered C/N Balance and High Sensitivity to Nitrogen Toxicity
Provisionally accepted
- University of Wisconsin-Madison, Madison, United States
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Plants invest large amounts of resources to produce the twenty proteinogenic amino acids that are essential for growth. However, we still lack a comprehensive understanding of the regulation of amino acid metabolism during the plant life cycle. Plants have a highly conserved ACT domain repeats (ACR) family proteins, which are structurally similar to the bacterial sensor protein GlnD that regulates a key enzyme for nitrogen assimilation and amino acid biosynthesis, glutamine synthetase (GS). Here, we investigated the role of the Arabidopsis ACR proteins ACR11 and ACR12, which are targeted to plastids, where most amino acids are synthesized in plants. Whereas acr12 knock-out plants only showed a minor reduction in growth under specific conditions, acr11 mutants exhibited markedly delayed growth and altered carbon/nitrogen balance. At the metabolic level, acr11 plants showed overaccumulation of free amino acids and other nitrogen-containing metabolites, particularly when grown under high nitrogen conditions, suggesting that ACR11 may be a negative regulator of nitrogen metabolism. Further, acr11 plants exhibited a drastic decrease in keto acid intermediates from central carbon metabolism that are precursors to amino acid biosynthesis. Analysis of total GS activity, a potential regulatory target for ACR11 according to previous studies, shows that acr11 plants have similar levels of GS activity compared to wild type under the growth conditions tested here, suggesting that ACR11 may regulate other molecular targets besides GS.
Keywords: amino acid metabolism, nitrogen metabolism, nitrogen assimilation, ACT domains repeats, Carbon/nitrogen balance
Received: 04 Aug 2025; Accepted: 07 Nov 2025.
Copyright: © 2025 Kunkel, Maeda and El-Azaz. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Jorge El-Azaz, elazazciudad@wisc.edu
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