The molecular logic of Gtr1/2- and Pib2-dependent TORC1 regulation in budding yeast.
The Target of Rapamycin kinase Complex 1 (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 at least three distinct signaling states: (i) a Gtr1/2 on, Pib2 on, rapid growth state in nutrient replete conditions; (ii) a Gtr1/2 inhibited, 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 multilevel response via a single kinase, but the behavior has been overlooked since most studies follow signaling to a single reporter protein.
Mesh Terms:
Carrier Proteins, Gene Expression Regulation, Fungal, Mechanistic Target of Rapamycin Complex 1, Monomeric GTP-Binding Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Signal Transduction, Transcription Factors
Carrier Proteins, Gene Expression Regulation, Fungal, Mechanistic Target of Rapamycin Complex 1, Monomeric GTP-Binding Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Signal Transduction, Transcription Factors
Elife
Date: Jul. 07, 2025
PubMed ID: 40622848
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