Structure-based engineering of Tor complexes reveals that two types of yeast TORC1 produce distinct phenotypes

Area of Science:

• Cellular signaling pathways
• Protein complex engineering
• Yeast genetics

Background:

• Target of rapamycin (Tor) complex 1 (TORC1) is crucial for cellular response to environmental cues and is linked to diseases.
• Budding yeast Saccharomyces cerevisiae possesses two TORC1 types (Tor1- and Tor2-containing) with assumed identical functions.

Purpose of the Study:

• To computationally model TORC1 complex structures.
• To engineer a Tor2 mutant capable of forming Tor complex 2 (TORC2) but not TORC1.
• To investigate the functional differences between the two TORC1 types.

Main Methods:

• Computational modeling of protein complex structures.
• Rational engineering of a Tor2 mutant based on structural data.
• Functional analysis of the engineered mutant in yeast.

Main Results:

• A Tor2 mutant was successfully engineered to alter TORC1 complex formation.
• The two TORC1 types were shown to induce distinct cellular phenotypes.
• Differences in rapamycin, caffeine, and pH dependencies of cell growth were observed.
• Variations in replicative and chronological lifespan were detected between TORC1 types.

Conclusions:

• The study demonstrates the utility of structure-based engineering for redesigning protein complex states.
• The findings reveal functional divergence between previously indistinguishable TORC1 complexes.
• This approach offers insights into molecular evolution and lifespan regulation.