Yeast thioredoxin reductase Trr1p controls TORC1-regulated processes

Area of Science:

• Cellular Biology
• Biochemistry
• Metabolism

Background:

• The thioredoxin system regulates cellular redox balance, with thioredoxin reductase (TRR1) providing reducing power.
• The Target Of Rapamycin Complex 1 (TORC1) pathway controls cell growth and metabolism based on nutrient availability.
• TORC1 represses catabolic processes like autophagy during nutrient-rich conditions.

Purpose of the Study:

• To investigate the impact of deleting yeast cytosolic thioredoxin reductase (TRR1) on cellular metabolism and life span.
• To explore the relationship between the thioredoxin system and the TORC1 pathway under various environmental conditions.

Main Methods:

• Deletion of the TRR1 gene in yeast.
• Analysis of yeast growth and chronological life span in grape juice fermentation.
• Assessment of oxidative stress tolerance.
• Evaluation of TORC1 pathway activity markers and related protein modifications.

Main Results:

• TRR1 deletion shortened chronological life span and reduced growth during fermentation.
• Oxidative stress tolerance decreased, but catalase and glutathione levels increased as a compensatory response.
• TRR1 deletion led to sensitivity to TORC1 inhibitors (e.g., rapamycin), associated with reduced Tor2p kinase levels.
• Autophagy induced by nitrogen starvation was diminished in the trr1Δ mutant.
• Dephosphorylation of ribosomal protein Rsp6p in response to rapamycin was impaired in the TRR1 deletion strain.

Conclusions:

• Yeast thioredoxin reductase Trr1p plays a significant role in regulating cellular metabolism, life span, and redox homeostasis.
• A complex interplay exists between the thioredoxin system and the TORC1 pathway, influencing growth, stress response, and autophagy.
• Trr1p appears to be involved in the stability of Tor2p kinase, impacting TORC1 signaling.