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Cell growth control by stable R bg2/ G ir2 complex formation under amino acid starvation
Author(s) -
Ishikawa Kosuke,
Ito Koichi,
Inoue Junichiro,
Semba Kentaro
Publication year - 2013
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/gtc.12082
Subject(s) - biology , amino acid , yeast , gtp' , cell growth , saccharomyces cerevisiae , biochemistry , microbiology and biotechnology , starvation , cell , activator (genetics) , gene , enzyme , endocrinology
The molecular fine‐tuning mechanisms underlying adaptive responses to environmental stresses in eukaryotes remain largely unknown. Here, we report on a novel stress‐induced cell growth control mechanism involving a highly conserved complex containing R bg2 and G ir2 subunits, which are the budding yeast orthologs of human D rg2 and D frp2, respectively. We found that the complex is responsible for efficient cell growth under amino acid starvation. Using native PAGE analyses, we observed that, individually, R bg2 and G ir2 were labile proteins. However, they formed a complex that stabilized each other, and this stability became significantly enhanced after amino acid starvation. We observed that the stabilization of the complex was strictly dependent on GDP or GTP binding to R bg2. A point mutation ( S 77 N ) that inactivated nucleotide binding impaired formation of the complex and disrupted the stress‐induced cell growth. Interestingly, the complex bound the translational activator G cn1 in a dose‐dependent manner according to the stress level, suggesting a dynamic association with the cellular translational machinery. We propose that the R bg2/ G ir2 complex is a modulator that maintains cellular homoeostasis, thus promoting the survival of eukaryotic organisms in stressful environments.