Pib2 is a cysteine sensor involved in TORC1 activation in Saccharomyces cerevisiae

Cell Rep. 2024 Jan 23;43(1):113599. doi: 10.1016/j.celrep.2023.113599. Epub 2023 Dec 20.

Abstract

Target of rapamycin complex 1 (TORC1) is a master regulator that monitors the availability of various amino acids to promote cell growth in Saccharomyces cerevisiae. It is activated via two distinct upstream pathways: the Gtr pathway, which corresponds to mammalian Rag, and the Pib2 pathway. This study shows that Ser3 was phosphorylated exclusively in a Pib2-dependent manner. Using Ser3 as an indicator of TORC1 activity, together with the established TORC1 substrate Sch9, we investigated which pathways were employed by individual amino acids. Different amino acids exhibited different dependencies on the Gtr and Pib2 pathways. Cysteine was most dependent on the Pib2 pathway and increased the interaction between TORC1 and Pib2 in vivo and in vitro. Moreover, cysteine directly bound to Pib2 via W632 and F635, two critical residues in the T(ail) motif that are necessary to activate TORC1. These results indicate that Pib2 functions as a sensor for cysteine in TORC1 regulation.

Keywords: CP: Molecular biology; Cysteine; Pib2; TORC1; mTORC1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / metabolism
  • Animals
  • Apoptosis Regulatory Proteins / metabolism
  • Cysteine / metabolism
  • Mammals / metabolism
  • Mechanistic Target of Rapamycin Complex 1 / metabolism
  • Saccharomyces cerevisiae Proteins* / metabolism
  • Saccharomyces cerevisiae* / metabolism
  • Transcription Factors / metabolism

Substances

  • Saccharomyces cerevisiae Proteins
  • Mechanistic Target of Rapamycin Complex 1
  • Cysteine
  • Transcription Factors
  • Amino Acids
  • Pib2 protein, S cerevisiae
  • Apoptosis Regulatory Proteins