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Research

Our study focuses on nutrient sensing - in particular amino acid sensing - in eukaryotic cells. Amino acids are among the basic building blocks of all living organisms. In eukaryotic cells, a dedicated pathway, the mTORC1 pathway, senses the presence or absence of amino acids in the environment, to license cell growth. We are interested in using biochemical and biophysical tools including enzymatic kinetics, structural biology (cryo-EM), and single molecule biophysics, to investigate the mTORC1 pathway at the molecular level. We aim to gain a fundamental understanding of this biological process and how its dysfunction could lead to human disease.

 

Kinetic analysis of enzymatic functions

Amino acid sensing is a dynamic process. Cells need to respond to nutrient-level changes on the time scale of several minutes. To achieve this temporal control and maintain cell survival, protein complexes within the mTORC1 pathway are precisely regulated. We aim to use enzymatic kinetics to understand how protein complexes interact with one another during the amino acid sensing process.

 

Structural illumination of key protein complexes

On the lysosomal surface, mTORC1 pathway components form isolated super-complexes that have distinct functions. Without structural information, we cannot establish strong structure-function relationships. We therefore aim to use structural biology tools to visualize the key protein complexes in mTORC1 pathway.

 

Single molecule reconstitution in vitro

In cells, multiple regulators control the function of the Rag GTPases, which raises the interesting question of how these regulators may compete or collaborate with one another. This question is difficult to answer in ensemble, especially within a mixed population where a single Rag dimer could bind to multiple regulators. We aim to develop a fluorescence-based single-molecule method to directly visualize the spatial organization of Rag-related protein complexes.