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TORC1 phosphorylates and inhibits the ribosome preservation factor Stm1 to activate dormant ribosomes

Sunil Shetty1, Jon Hofstetter1, Stefania Battaglioni1

  • 1Biozentrum, University of Basel, Basel, Switzerland.

The EMBO Journal
|January 24, 2023
PubMed

Insights

Target of rapamycin complex 1 (TORC1) regulates ribosome dormancy. Stm1 protein preserves dormant ribosomes under nutrient limitation, and TORC1 directly inhibits Stm1 to resume translation, a conserved mechanism.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Target of rapamycin complex 1 (TORC1) controls ribosome biogenesis and degradation based on nutrient availability.
  • Cells maintain dormant ribosomes during nutrient scarcity, but their regulation is unclear.

Purpose of the Study:

  • To investigate the regulation of dormant ribosomes under nutrient-limited conditions.
  • To elucidate the role of the ribosome preservation factor Stm1 in TORC1-mediated ribosome regulation.

Main Methods:

  • Yeast genetics and molecular biology techniques.
  • Rapamycin treatment and nitrogen starvation to inhibit TORC1.
  • Analysis of ribosome formation, translation status, and degradation.

Main Results:

  • TORC1 inhibition induces Stm1-mediated formation of dormant 80S ribosomes.
  • Stm1 protects these dormant ribosomes from proteasomal degradation.
  • TORC1 directly phosphorylates and inhibits Stm1 upon nutrient refeeding, reactivating translation.
  • Mammalian SERBP1 acts similarly to Stm1, indicating conserved regulation.

Conclusions:

  • TORC1 directly regulates ribosomal dormancy through the ribosome preservation factor Stm1.
  • This mechanism of regulating dormant ribosomes is conserved across yeast and mammals.
  • Stm1 is a key mediator of ribosome preservation under nutrient stress.
Keywords:
SERBP1Stm1TORC1dormant ribosomesproteasome

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