Submitted on October 25, 2007
Accepted on January 11, 2008
Role of Hog1 and Yaf9 in the transcriptional response of Saccharomyces cerevisiae to caesium chloride
Valerio Del Vescovo1, Viviana Casagrande1, Michele Maria Bianchi1, Eugenia Piccinni1, Laura Frontali1, Cristina Militti1, Vivienne Fardeau2, Frederic Devaux2, Claudio Di Sanza3, Carlo Presutti3, and Rodolfo Negri1*
1 Biologia Cellulare e dello Sviluppo, Universita di Roma "La Sapienza", Roma, Italy
2 Laboratoire de Genomique CNRS, Ecole Normale Superieure, Paris, France
3 Genetica e Biologia Molecolare, Universita di Roma "La Sapienza", Roma, Italy
* To whom correspondence should be addressed. E-mail: rodolfo.negri{at}uniroma1.it.
We analysed the global transcriptional response of S. cerevisiae cells exposed to different concentrations of CsCl in the growth medium and at different times from addition. Early responsive genes were mainly involved in cell wall structure and biosynthesis. About half of the induced genes were previously shown to respond to other alkaline cations in a Hog1-dependent fashion. Western blot analysis confirmed that caesium concentrations as low as 100 mM activate Hog1 phosphorylation. Another important fraction of the caesium modulated genes requires Yaf9p for full responsiveness as shown by the transcriptome of a yaf9 deleted strain in presence of caesium.
We showed that a cell wall restructuring process promptly occurs in response to caesium addition which is dependent on the presence of both Hog1 and Yaf9 proteins. Moreover, the sensitivity to low concentration of caesium of the yaf9 deleted strain is not observed in a strains carrying hog1/yaf9 double deletion.
We conclude that the observed early transcriptional modulation of cell wall genes has a crucial role in S. cerevisiae adaptation to caesium.
