Abstract
Myriocin is a potent inhibitor of sphingolipid biosynthesis that increases lifespan in a variety of model organisms, but how slowing sphingolipid biosynthesis promotes longevity remains unknown. Previously, we reported that myriocin treatment of yeast cells triggers an acute decline in the abundance of most amino acids, resulting in a state of amino acid restriction. Myriocin also triggers the endocytic downregulation of the methionine transporter Mup1, although its effect on other nutrient transporters is unknown. Here, we characterized a panel of different PM proteins – including amino acid transporters, hexose transporters, proton pumps, and signaling receptors – during a myriocin treatment time course. In contrast to Mup1, all other PM proteins examined were either unaffected or accumulated at the PM in response to myriocin treatment. Notably, myriocin treatment inhibits bulk endocytosis after 4 hours of treatment, which may account for the accumulation of various PM proteins in response to myriocin. Our data indicates that the mechanism of myriocin-induced Mup1 endocytosis is distinct from methionine-induced Mup1 endocytosis in that it is dependent on the Rsp5 adaptor Art2, C-terminal lysine residues, and the formation of K63-linked ubiquitin polymers. These findings shed new light on how cells adapt to sphingolipid depletion and reveal a novel mechanism for endocytic clearance of Mup1.
Competing Interest Statement
The authors have declared no competing interest.
