Dr. Yihan Dong
Research Keywords: TOR signaling, autophagy, nutrient deficiency, DNA methylation.
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Growth of eukaryotic cells is regulated by the Target of Rapamycin (TOR). The strongest activator of TOR in metazoa is amino acid availability. The established transducers of amino acid sensing to TOR in metazoa are absent in plants. Hence a fundamental question is how amino acid sensing is achieved in photo-autotrophic organisms. Here we demonstrate that the plant Arabidopsis does not sense the sulfur-containing amino acid cysteine itself, but its biosynthetic precursors. We identify the kinase GCN2 as a sensor of the carbon/nitrogen precursor availability, whereas limitation of the sulfur precursor is transduced to TOR by down-regulation of glucose metabolism. The down-regulated TOR activity caused decreased translation, lowered meristematic activity, and elevated autophagy. Our results uncover a plant-specific adaptation of TOR function. In concert with GCN2, TOR allows photo-autotrophic eukaryotes to coordinate the fluxes of carbon, nitrogen and sulfur for efficient cysteine biosynthesis under varying external nutrient supply.
Pfeiffer, A., Janocha, D., Dong, Y., Medzihradszky, A., Schöne, S., Daum, G., Suzaki, T., Forner, J., Langenecker, T., Rempel, E., et al. (2016). Integration of light and metabolic signals for stem cell activation at the shoot apical meristem. eLife 5, e17023.
Dong Y, Silbermann M, Speiser A, Forieri I, Linster E, Poschet G, Allboje A, Watanabe M, Sticht C, Teleman A, Deragon J-M, Saito K, Hell R, and Wirtz M. (2017). Sulfur availability regulates plant growth via glucose-TOR signaling. Nature Communications, 8, 1174.
Speiser A., Silbermann M., Dong Y., Haberland S., Uslu V.V., Wang S., Bangash S.A.K., Reichelt M., Meyer A.J., Wirtz M., Hell R. (2018) Partitioning of sulfur between glutathione and protein synthesis determines growth of Arabidopsis. Plant Physiology, accepted.
Dong Y., Teleman A., Jedmowski C., Wirtz M., Hell R. (2018) The Arabidopsis THADA homolog modulates TOR activity and cold acclimation. Plant Biology, accepted.