Regulation of the CRH1 expression in the compensatory response to cell wall damage in Saccharomyces cerevisiae.
Estefania Rodriguez, Raul Garcia, Clara Bermejo, Patricia Arias, Jose Manuel Rodriguez-Peña, Carmen Rivas, Cesar Nombela, Javier Arroyo
Microbiology, Faculty of Pharmacy, U.C.M., Pza.Ramon y Cajal, Madrid, 28040, Spain
The cell wall of Saccharomyces cerevisiae is a dynamic structure that undergoes many changes during cell growth and under cell damage conditions. To insure cell integrity when damaged, a compensatory mechanism is triggered in these cells, and thus, cell wall is modified. CRH1, encoding a trasglycosidase of the Crh family proteins-Crh1p, Crh2p and Crr1p-, is involved in cell wall assembly, is cell cycle regulated -G1-M/G1- and is induced in the compensatory response. Using knockout strains in different MAPK pathways, we have caracterized the mechanisms regulating the transcriptional activation of CRH1 in response to different kinds of cell wall stress: Congo red, that binds to chitin, and Zymoliase that degradates the glucan network. Whilst CRH1 indution by Congo red is only regulated through the Cell Integrity pathway, the trascripcional activation of this gene by Zymoliase depends on the Slt2p and Hog1p MAPKs, suggesting a role for both pathways under these circumstances. Using a Crh1-lacZ reporter and antibodies against the activated Slt2p and Hog1p we have analyzed the involvement of several elements of these pathways in the response to Zymoliase. Besides, phenotype studies perfectly correlate to the transcriptional data. Deletions of the promoter elements, allowed us to define the motifs related to the stress-dependent response CRH1. Moreover, microarray assays, demonstrated that this different regulation of cell wall damage is not only restricted to CRH1 expression.