Cellular Death & Stress Responses | Cell Signaling | Microbial Physiology & Metabolism | Control of Gene Expression | Cellular Microbiology & Pathogenesis
Mtl1 is a membrane receptor of Saccharomyces cerevisiae required to inhibit TOR and RAS/cAMP functions upon determined environmental stresses
Mima Ivanova, Petkova Nuria Pujol-Carrion, Maria Angeles de la Torre-Ruiz*
*Corresponding author: Maria Angeles de la Torre-Ruiz
Ciències Mèdiques Bàsiques-IRBLleida, Faculty of Medicine, University of Lleida, Lleida, Spain
F1000Posters 2011, 2: 893 (poster) [ENGLISH]
Biochemical Society 2011 - Signalling: A Biochemical Society Centenary Celebration meeting, 8 - 10 Jun 2011, P025
Mtl1 is a member of the cell wall integrity pathway (CWI) of Saccharomyces cerevisiae, which functions as a cell wall sensor for oxidative stress. Genome-wide transcriptional analysis revealed a cluster of genes that were downregulated in the absence of Mtl1. Many of these genes were potentially regulated by the general stress response factor Msn2/Msn4. In response to rapamycin, caffeine, glucose starvation and oxidative stress provoked by H2O2, mtl1 presents a significant loss of viability as well as a deficiency in the transcriptional response mediated by Msn2/Msn4.
The Mtl1 function was required i) to induce ribosomal gene repression, ii) to induce the general stress response driven by the transcription factor Msn2/Msn4 and iii) to activate the CWI pathway in response to both glucose starvation and oxidative stress.
We detected higher cAMP levels in the mtl1 mutant than in wild type cells indicative of upregulated RAS2-PKA activity. Disruption of TOR1, disruption of RAS2 or hyperactivation of Rho1 restored both the viability and the transcriptional function (both ribosomal and Msn2/Msn4 dependent gene expression) in the mtl1 mutant to almost wild type levels when cells were starved of glucose or stressed with H2O2.
Taking our results together, we propose an essential role for Mtl1 in signaling oxidative stress and quiescence to the CWI pathway and to the general stress response through Rho1 and the inhibition of either the TOR1 or RAS2 functions. These mechanisms would be required to allow cells to adapt to both oxidative and nutritional stresses.
No relevant conflicts of interest declared.
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