The Yeast Transcription Factor Crz1 Is Activated by Light in a Ca2+/Calcineurin-Dependent and PKA-Independent Manner
Journal article, 2013

Light in the visible range can be stressful to non-photosynthetic organisms. The yeast Saccharomyces cerevisiae has earlier been reported to respond to blue light via activation of the stress-regulated transcription factor Msn2p. Environmental changes also induce activation of calcineurin, a Ca2+/calmodulin dependent phosphatase, which in turn controls gene transcription by dephosphorylating the transcription factor Crz1p. We investigated the connection between cellular stress caused by blue light and Ca2+ signalling in yeast by monitoring the nuclear localization dynamics of Crz1p, Msn2p and Msn4p. The three proteins exhibit distinctly different stress responses in relation to light exposure. Msn2p, and to a lesser degree Msn4p, oscillate rapidly between the nucleus and the cytoplasm in an apparently stochastic fashion. Crz1p, in contrast, displays a rapid and permanent nuclear localization induced by illumination, which triggers Crz1p-dependent transcription of its target gene CMK2. Moreover, increased extracellular Ca2+ levels stimulates the light-induced responses of all three transcription factors, e. g. Crz1p localizes much quicker to the nucleus and a larger fraction of cells exhibits permanent Msn2p nuclear localization at higher Ca2+ concentration. Studies in mutants lacking Ca2+ transporters indicate that influx of extracellular Ca2+ is crucial for the initial stages of light-induced Crz1p nuclear localization, while mobilization of intracellular Ca2+ stores appears necessary for a sustained response. Importantly, we found that Crz1p nuclear localization is dependent on calcineurin and the carrier protein Nmd5p, while not being affected by increased protein kinase A activity (PKA), which strongly inhibits light-induced nuclear localization of Msn2/4p. We conclude that the two central signalling pathways, cAMP-PKA-Msn2/4 and Ca2+-calcineurin-Crz1, are both activated by blue light illumination.

budding yeast

calcium influx

h+/ca2+ exchange


affinity camp-phosphodiesterase


signaling pathway





Kristofer Bodvard

University of Gothenburg

Chalmers, Applied Physics, Bionanophotonics

Anna Jorhov

University of Gothenburg

Anders Blomberg

University of Gothenburg

Mikael Molin

University of Gothenburg

Mikael Käll

Chalmers, Applied Physics, Bionanophotonics


1932-6203 (ISSN)

Vol. 8 1 Article Number: e53404 - e53404

Subject Categories

Physical Sciences

Biological Sciences



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