Molecular and structural mechanisms of nutrient sensing in the mTORC1 pathway

Primary nutrient sensors directly bind metabolites and undergo conformational changes that signal through core pathways to coordinate metabolic and cellular outcomes. Sensing of amino acids, lipids, sugars, and nucleotides is critical for the master growth regulatory Ser/Thr kinase, mechanistic target of rapamycin complex 1 (mTORC1), to promote growth and proliferation. Systematic proteomic and bioinformatic studies have accelerated the discovery of primary nutrient sensors upstream of mTORC1, whereas structural biology has shed light on how binding to their cognate metabolites triggers mTORC1-dependent signaling responses. This review focuses on recently reported amino acid and lipid sensors upstream of mTORC1 and highlights structural and functional features of these sensors that illuminate fundamental principles of nutrient detection and signal transduction.