Despite the importance of glucose and amino acids for energy metabolism, interactions between the two nutrients are not well understood. We provide evidence for a role of leucyl-tRNA synthetase 1 (LARS1) in glucose-dependent control of leucine usage. Upon glucose starvation, LARS1 was phosphorylated by Unc-51 like autophagy activating kinase 1 (ULK1) at the residues crucial for leucine binding. The phosphorylated LARS1 showed decreased leucine binding, which may inhibit protein synthesis and help save energy. Leucine that is not used for anabolic processes may be available for catabolic pathway energy generation. The LARS1-mediated changes in leucine utilization might help support cell survival under glucose deprivation. Thus, depending on glucose availability, LARS1 may help regulate whether leucine is used for protein synthesis or energy production.
Bibliographical noteFunding Information:
We thank H.-S. Jeong for supplying AMPKg1 null 293A cells. Funding: This work was supported by the Global Frontier Project grant [NRF-M3A6A4-2010-0029785 (Sunghoon Kim), NRF-2014M3A6A4075060 (H.-S.P.), NRF-2015M3A6A4076702 (G.-S.H.), and NRF-2013M3A6A4044795 (K.Y.H.)] of the National Research Foundation funded by the Ministry of Science and ICT (MSIT) of Korea; the Korea Basic Science Institute (T39720) (G.-S.H.); and the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education [2018R1A6A1A03023718 (J.M.H.)].
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