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 prot ein. These cellular responses have been regarded as compensating for cell w all damage in order to maintain cell wall integrity. Here. we report the id entification, by genome-wide screening, of 22 genes that are transcriptiona lly up-regulated in fks1 Delta 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 i dentified Rlm1-binding sequences as being responsible for the up-regulation following disruption of FKS1. Using the rlm1 Delta tetOp-FKS1 strain, in w hich the expression of FKS1 can be repressed by doxycycline, we examined th e requirement for Rlm1 for the transcriptional up-regulation of these five genes. Three of the five genes were not up-regulated by doxycycline, indica ting that Rlm1 mediates their up-regulation when FKS1 is inactivated. The r emaining two genes were up-regulated by doxycycline, suggesting that a tran scription factor other than Rlm1 is involved in their response to disruptio n of FKS1.