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Acute glucose starvation activates the nuclear localization signal of a stress‐specific yeast transcription factor

Wolfram Görner, Erich Durchschlag, Julia Wolf, Elizabeth L. Brown, Gustav Ammerer, Helmut Ruis, Christoph Schüller

Author Affiliations

  1. Wolfram Görner2,
  2. Erich Durchschlag1,
  3. Julia Wolf1,
  4. Elizabeth L. Brown1,
  5. Gustav Ammerer*,1,
  6. Helmut Ruis1 and
  7. Christoph Schüller1
  1. 1 Vienna Biocenter, Institut für Biochemie und Molekulare Zellbiologie der Universität Wien and Ludwig Boltzmann‐Forschungsstelle für Biochemie, Dr Bohrgasse 9, A‐1030, Wien, Austria
  2. 2 Present address: Max Planck Institute of Cell Biology and Genetics, Pfotenhauerstrasse 108, D‐01307, Dresden, Germany
  1. *Corresponding author. E‐mail: ga{at}abc.univie.ac.at
  1. W.Görner and E.Durchschlag contributed equally to this work.

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Abstract

In yeast, environmental conditions control the transcription factor Msn2, the nuclear accumulation and function of which serve as a sensitive indicator of nutrient availablity and environmental stress load. We show here that the nuclear localization signal (NLS) of Msn2 is a direct target of cAMP‐dependent protein kinase (cAPK). Genetic analysis suggests that Msn2‐NLS function is inhibited by phosphorylation and activated by dephosphorylation. Msn2‐NLS function is unaffected by many stress conditions that normally induce nuclear accumulation of full‐length Msn2. The Msn2‐NLS phosphorylation status is, however, highly sensitive to carbohydrate fluctuations during fermentative growth. Dephosphorylation occurs in >2 min after glucose withdrawal but the effect is reversed rapidly by refeeding with glucose. This response to glucose depletion is due to changes in cAPK activity rather than an increase in protein phosphatase activity. Surprisingly, the classical glucose‐sensing systems are not connected to this rapid response system. Our results further imply that generic stress signals do not cause short‐term depressions in cAPK activity. They operate on Msn2 by affecting an Msn5‐dependent nuclear export and/or retention mechanism.

  • Received September 18, 2001.
  • Revision received November 9, 2001.
  • Accepted November 14, 2001.
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