Up-regulation of genes encoding glycosylphosphatidylinositol (GPI)-attached proteins in response to cell wall damage caused by disruption of FKS1 in Saccharomyces cerevisiae.

FKS1 and FKS2 encode alternative catalytic subunits of the glucan synthases that are responsible for synthesis of beta-1,3-glucan in the Saccharomyces cerevisiae cell wall. Disruption of FKS1 reduces the glucan content of the cell wall, increases chitin content and activates the expression of CWP1, which encodes a glycosylphosphatidylinositol (GPI)-dependent cell wall protein. These cellular responses have been regarded as compensating for cell wall damage in order to maintain cell wall integrity. Here, we report the identification, by genome-wide screening, of 22 genes that are transcriptionally up-regulated in fks1delta cells. Among them, five genes were found to encode GPI-attached proteins, three of which are covalently associated with the cell wall. Deletion and replacement analysis of the promoter regions identified Rlm1-binding sequences as being responsible for the up-regulation following disruption of FKS1. Using the rlm1delta tetOp-FKS1 strain, in which the expression of FKS1 can be repressed by doxycycline, we examined the requirement for Rlm1 for the transcriptional up-regulation of these five genes. Three of the five genes were not up-regulated by doxycycline, indicating that Rlm1 mediates their up-regulation when FKS1 is inactivated. The remaining two genes were up-regulated by doxycycline, suggesting that a transcription factor other than Rlm1 is involved in their response to disruption of FKS1.