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@article{838003,
author = {Špírek, Mário and Liu, Zhengchang and Thornton, Janet and Butow, Ronald},
article_location = {Washington, D.C.},
article_number = {2},
keywords = {SPS amino-acid sensing pathway; Ptr3; phosphorylation; yeast},
language = {eng},
issn = {0270-7306},
journal = {Molecular and Cellular Biology},
title = {Activation of the SPS Amino Acid-Sensing Pathway in Saccharomyces cerevisiae Correlates with the Phosphorylation State of a Sensor Component, Ptr3},
url = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=17984223},
volume = {28},
year = {2008}
}
TY - JOUR
ID - 838003
AU - Špírek, Mário - Liu, Zhengchang - Thornton, Janet - Butow, Ronald
PY - 2008
TI - Activation of the SPS Amino Acid-Sensing Pathway in Saccharomyces cerevisiae Correlates with the Phosphorylation State of a Sensor Component, Ptr3
JF - Molecular and Cellular Biology
VL - 28
IS - 2
SP - 551–563
EP - 551–563
PB - ASM
SN - 02707306
KW - SPS amino-acid sensing pathway
KW - Ptr3
KW - phosphorylation
KW - yeast
UR - http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=17984223
N2 - Cells of the budding yeast Saccharomyces cerevisiae sense extracellular amino acids and activate expression of amino acid permeases through the SPS-sensing pathway, which consists of Ssy1, an amino acid sensor on the plasma membrane, and two downstream factors, Ptr3 and Ssy5. Upon activation of SPS signaling, two transcription factors, Stp1 and Stp2, undergo Ssy5-dependent proteolytic processing that enables their nuclear translocation. Here we show that Ptr3 is a phosphoprotein whose hyperphosphorylation is increased by external amino acids and is dependent on Ssy1 but not on Ssy5. A deletion mutation in GRR1, encoding a component of the SCFGrr1 E3 ubiquitin ligase, blocks amino acid-induced hyperphosphorylation of Ptr3. We found that two casein kinase I (CKI) proteins, Yck1 and Yck2, previously identified as positive regulators of SPS signaling, are required for hyperphosphorylation of Ptr3. Loss- and gain-of-function mutations in PTR3 result in decreased and increased Ptr3 hyperphosporylation, respectively. We found that a defect in PP2A phosphatase activity leads to the hyperphosphorylation of Ptr3 and constitutive activation of SPS signaling. Two-hybrid analysis revealed interactions between the N-terminal signal transduction domain of Ssy1 with Ptr3 and Yck1. Our findings reveal that CKI and PP2A phosphatase play antagonistic roles in SPS sensing by regulating Ptr3 phosphorylation.
ER -
ŠPÍREK, Mário, Zhengchang LIU, Janet THORNTON a Ronald BUTOW. Activation of the SPS Amino Acid-Sensing Pathway in Saccharomyces cerevisiae Correlates with the Phosphorylation State of a Sensor Component, Ptr3. \textit{Molecular and Cellular Biology}. Washington, D.C.: ASM, 2008, roč.~28, č.~2, s.~551–563. ISSN~0270-7306.
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