Amino acid residues required for Gtr1p-Gtr2p complex formation and its interactions with the Ego1p-Ego3p complex and TORC1 components in yeast

Takeshi Sekiguchi, Yoshiaki Kamada, Nobuaki Furuno, Minoru Funakoshi, Hideki Kobayashi

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The yeast Ras-like GTPases Gtr1p and Gtr2p form a heterodimer, are implicated in the regulation of TOR complex 1 (TORC1) and play pivotal roles in cell growth. Gtr1p and Gtr2p bind Ego1p and Ego3p, which are tethered to the endosomal and vacuolar membranes where TORC1 functions are regulated through a relay of amino acid signaling interactions. The mechanisms by which Gtr1p and Gtr2p activate TORC1 remain obscure. We probed the interactions of the Gtr1p-Gtr2p complex with the Ego1p-Ego3p complex and TORC1 subunits. Mutations in the region (179-220 a.a.) following the nucleotide-binding region of Gtr1p and Gtr2p abrogated their mutual interaction and resulted in a loss in function, suggesting that complex formation between Gtr1p and Gtr2p was indispensable for TORC1 function. A modified yeast two-hybrid assay showed that Gtr1p-Gtr2p complex formation is important for its interaction with the Ego1p-Ego3p complex. GTP-bound Gtr1p interacted with the region containing the HEAT repeats of Kog1p and the C-terminal region of Tco89p. The GTP-bound Gtr2p suppressed a Kog1p mutation. Our findings indicate that the interactions of the Gtr1p-Gtr2p complex with the Ego1p-Ego3p complex and TORC1 components Kog1p and Tco89p play a role in TORC1 function.

Original languageEnglish
Pages (from-to)449-463
Number of pages15
JournalGenes to Cells
Volume19
Issue number6
DOIs
Publication statusPublished - Jun 2014

All Science Journal Classification (ASJC) codes

  • Genetics
  • Cell Biology

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