# An aminoacyl tRNA synthetase is a nitrogen sensor that activates TOR in plants

> **NIH NIH DP5** · UNIVERSITY OF WISCONSIN-MADISON · 2020 · $122,855

## Abstract

Contact PD/PI: Brunkard, Jacob Oliver
PROJECT SUMMARY: Eukaryotic growth is regulated by TOR, a kinase that is activated by amino
acids and glucose and then broadly promotes anabolism, including protein, lipid, and nucleotide
synthesis. TOR dysregulation causes or contributes to an array of human diseases, including cancer,
obesity, viral infections, diabetes, aging, and neurodegeneration. TOR signaling is under intense
investigation among yeast and animal cell biologists, who seek to characterize the mechanisms that
control TOR signaling networks in order to develop treatments to fine-tune TOR activity as therapies
for human diseases. Much less is known about the TOR signaling network in the other major
eukaryotic lineage, plants. This project uses a combination of genetic, biochemical, genomic, and
proteomic approaches to pursue my recent groundbreaking discovery of an amino acid sensor that
activates TOR in plant cells. No amino acid sensors have been previously characterized in plants,
although amino acids are the primary form of nitrogen found in many natural soils, and amino acids
are the primary transported form of nitrogen between organs in most plant species. Understanding
how plants sense and respond to nitrogen is a top priority for plant molecular biologists, because
global crop yields rely massively on heavy use of environmentally-harmful and expensive
petrochemical fertilizers. This proposed investigation of a nitrogen sensor that activates TOR will
enable intelligent breeding efforts to produce crops that are able to generate high crop yields in low
nitrogen environments by modulating plants' nitrogen sensing mechanisms. The first specific aim of
this project is to first determine how nitrogen sources affect TOR activity, and then to confirm that the
proposed amino acid sensor, an aminoacyl tRNA synthetase, does act upstream of TOR signaling.
The second aim of this project is to use powerful contemporary proteomic techniques to identify
proteins that interact with TOR and/or the proposed nitrogen sensor to control nitrogen-mediated
TOR activation using powerful proteomic techniques. Finally, the role of the proposed nitrogen sensor
in plant development, crop yields, and responses to environmental nitrogen sources will be explored
in several of the most important global crop species. With this innovative approach to exploring how
amino acid sensing mechanisms have evolved with TOR signaling in eukaryotes, this project will
simultaneously advance understanding of how plants coordinate growth and development with
nitrogen availability, and provide original insights into amino acid-TOR networks that will benefit
biomedical studies of TOR cell biology in humans.
Project Summary/Abstract Page 6

## Key facts

- **NIH application ID:** 10484171
- **Project number:** 7DP5OD023072-06
- **Recipient organization:** UNIVERSITY OF WISCONSIN-MADISON
- **Principal Investigator:** Jacob O Brunkard
- **Activity code:** DP5 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $122,855
- **Award type:** 7
- **Project period:** 2021-09-08 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10484171

## Citation

> US National Institutes of Health, RePORTER application 10484171, An aminoacyl tRNA synthetase is a nitrogen sensor that activates TOR in plants (7DP5OD023072-06). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10484171. Licensed CC0.

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