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High-resolution Imaging and Analysis of Individual Astral Microtubule Dynamics in Budding Yeast
Published on: April 20, 2017
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Ait1 regulates TORC1 signaling and localization in budding yeast
Ryan L Wallace1, Eric Lu1, Xiangxia Luo1
1Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States.
Elife
|September 1, 2022
Summary
A novel protein, Ait1, regulates the target of rapamycin complex I (TORC1) pathway in yeast by binding to TORC1-Gtr1/2. This interaction controls cell growth and metabolism, particularly during nutrient starvation.
Area of Science:
- Cell Biology
- Molecular Biology
- Yeast Genetics
Background:
- Target of rapamycin complex I (TORC1) is a crucial regulator of cell growth and metabolism in eukaryotes.
- TORC1 activation is typically mediated by nitrogen/amino acid signals via Gtr1/2 (RagA/C) and SEAC/GATOR complexes.
- Regulation of TORC1 in simple eukaryotes like yeast by additional proteins remains largely unexplored.
Purpose of the Study:
- To investigate novel regulators of the TORC1 pathway in *Saccharomyces cerevisiae*.
- To elucidate the function and mechanism of the uncharacterized protein Ait1 in TORC1 signaling.
- To understand the evolutionary rewiring of TORC1 regulation in specific yeast families.
Main Methods:
- Yeast genetics and molecular biology techniques.
- Protein-binding assays to study TORC1-Ait1 interactions.
- Analysis of TORC1 activity under various growth and starvation conditions.
Main Results:
- The GPCR-like protein Ait1 binds to TORC1-Gtr1/2 in *Saccharomyces cerevisiae*.
- Ait1 sequesters TORC1 near the vacuole during log-phase growth.
- During amino acid starvation, Ait1 inhibits TORC1 via Gtr1/2, mimicking human SLC38A9 function.
- Ait1 is exclusively found in *Saccharomycetaceae/codaceae* yeast families, which lack canonical TORC1 regulators Rheb and TSC1/2.
Conclusions:
- Ait1 represents a novel regulator of TORC1 signaling in yeast.
- The TORC1 regulatory circuit in *Saccharomycetaceae/codaceae* has evolved unique mechanisms, distinct from other eukaryotes.
- This study reveals significant evolutionary rewiring of fundamental cellular pathways in simple eukaryotes.
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