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Complementary a-arrestin-ubiquitin ligase complexes control nutrient transporter endocytosis in response to amino acids
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Edité par CCSD ; eLife Sciences Publication -
International audience. How cells adjust nutrient transport across their membranes is incompletely understood. Previously, we have shown that S. cerevisiae broadly re-configures the nutrient transporters at the plasma membrane in response to amino acid availability, through endocytosis of sugar-and amino acid transporters (AATs) (Mü ller et al., 2015). A genome-wide screen now revealed that the selective endocytosis of four AATs during starvation required the a-arrestin family protein Art2/Ecm21, an adaptor for the ubiquitin ligase Rsp5, and its induction through the general amino acid control pathway. Art2 uses a basic patch to recognize C-terminal acidic sorting motifs in AATs and thereby instructs Rsp5 to ubiquitinate proximal lysine residues. When amino acids are in excess, Rsp5 instead uses TORC1-activated Art1 to detect N-terminal acidic sorting motifs within the same AATs, which initiates exclusive substrate-induced endocytosis. Thus, amino acid excess or starvation activate complementary a-arrestin-Rsp5-complexes to control selective endocytosis and adapt nutrient acquisition.