Key Features of Inhibitor Binding to the Human Mitochondrial Pyruvate Carrier Hetero-Dimer

The mitochondrial pyruvate carrier (MPC) has emerged as a promising drug target for metabolic disorders, including non-alcoholic steatohepatitis and diabetes, metabolically dependent cancers and neurodegenerative diseases. Human MPC is a protein complex, but the composition of its active form is debated and the mechanisms of transport and inhibition are not resolved. We have recombinantly expressed and purified the human hetero-complex MPC1L/MPC2 and demonstrate that it is a functional hetero-dimer, like the yeast MPC hetero-dimers. Unlike the latter, human MPC1L/MPC2 binds the known inhibitors with high potencies. We identify the essential chemical features shared between these structurally diverse inhibitors and demonstrate that high affinity binding is not attributed to covalent bond formation with MPC cysteines, as previously thought. We also identify 14 new inhibitors of MPC, one outperforming the most potent compound UK5099 by tenfold. Two of them are the commonly prescribed drugs entacapone and nitrofurantoin, suggesting possible off-target mechanisms associated with their adverse effects. This work advances our understanding of MPC inhibition and will accelerate the development of clinically relevant MPC modulators.