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

Kristofer Bodvard (Institutionen för teknisk fysik, Bionanofotonik ; Institutionen för kemi och molekylärbiologi) ; Anna Jorhov ; Anders Blomberg ; Mikael Molin ; Mikael Käll (Institutionen för teknisk fysik, Bionanofotonik)
PLoS ONE (1932-6203). Vol. 8 (2013), 1, p. Article Number: e53404 .
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: affinity camp-phosphodiesterase, protein-kinase-a, saccharomyces-cerevisiae, nuclear-localization, gene-expression, signaling pathway, calcium influx, budding yeast, environmental-changes, h+/ca2+ exchange



Denna post skapades 2013-03-19. Senast ändrad 2013-03-25.
CPL Pubid: 174833

 

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Institutioner (Chalmers)

Institutionen för teknisk fysik, Bionanofotonik (2007-2015)
Institutionen för kemi och molekylärbiologi (GU)

Ämnesområden

Fysik
Biologiska vetenskaper

Chalmers infrastruktur