Target of Rapamycin Inhibition in Chlamydomonas reinhardtii Triggers de Novo Amino Acid Synthesis by Enhancing Nitrogen Assimilation

The Plant Cell
Umarah MubeenPatrick Giavalisco

Abstract

The Target of Rapamycin (TOR) kinase is a central regulator of growth and metabolism in all eukaryotic organisms, including animals, fungi, and plants. Even though the inputs and outputs of TOR signaling are well characterized for animals and fungi, our understanding of the upstream regulators of TOR and its downstream targets is still fragmentary in photosynthetic organisms. In this study, we employed the rapamycin-sensitive green alga Chlamydomonas reinhardtii to elucidate the molecular cause of the amino acid accumulation that occurs after rapamycin-induced inhibition of TOR. Using different growth conditions and stable 13C- and 15N-isotope labeling, we show that this phenotype is accompanied by increased nitrogen (N) uptake, which is induced within minutes of TOR inhibition. Interestingly, this increased N influx is accompanied by increased activities of glutamine synthetase and glutamine oxoglutarate aminotransferase, the main N-assimilating enzymes, which are responsible for the rise in levels of several amino acids, which occurs within a few minutes. Accordingly, we conclude that even though translation initiation and autophagy have been reported to be the main downstream targets of TOR, the upregulation of de novo amino...Continue Reading

Citations

Feb 19, 2019·Journal of Experimental Botany·Marie-Hélène Montané, Benoît Menand
Mar 15, 2019·Journal of Experimental Botany·Muhammed Jamsheer KAshverya Laxmi
Feb 5, 2019·Journal of Experimental Botany·Yue WuJen Sheen
Jul 18, 2020·FEBS Letters·Shivani UpadhyayaBasuthkar Jagadeeshwar Rao
Jan 1, 2020·Biotechnology for Biofuels·Tomomi Takeuchi, Christoph Benning
Mar 29, 2019·Frontiers in Microbiology·Linxuan LiMaozhi Ren
Mar 3, 2020·Frontiers in Plant Science·Masataka Kajikawa, Hideya Fukuzawa
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Jul 9, 2021·Environmental Science and Pollution Research International·Satomi Mizukami-MurataHiromasa Yamashita
Jan 9, 2022·Proceedings of the National Academy of Sciences of the United States of America·Manuel J Mallén-PonceJosé L Crespo

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