Cecil JH, Padilla CM, Lipinski AA, Langlais PR, Luo X, Capaldi AP. The Molecular Logic of Gtr1/2 and Pib2 Dependent TORC1 Regulation in Budding Yeast.
bioRxiv 2023:2023.12.06.570342. [PMID:
38106135 PMCID:
PMC10723367 DOI:
10.1101/2023.12.06.570342]
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Abstract
The Target of Rapamycin kinase Complex I (TORC1) regulates cell growth and metabolism in eukaryotes. Previous studies have shown that, in Saccharomyces cerevisiae, nitrogen and amino acid signals activate TORC1 via the highly conserved small GTPases, Gtr1/2, and the phosphatidylinositol 3-phosphate binding protein, Pib2. However, it was unclear if/how Gtr1/2 and Pib2 cooperate to control TORC1. Here we report that this dual regulator system pushes TORC1 into three distinct signaling states: (i) a Gtr1/2 on, Pib2 on, rapid growth state in nutrient replete conditions; (ii) a Gtr1/2 off, Pib2 on, adaptive/slow growth state in poor-quality growth medium; and (iii) a Gtr1/2 off, Pib2 off, quiescent state in starvation conditions. We suggest that other signaling pathways work in a similar way, to drive a multi-level response via a single kinase, but the behavior has been overlooked since most studies follow signaling to a single reporter protein.
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