Role of Ppt1 in multiple stress responses in Candida albicans

To study the function of CaPpt1, we deleted PPT1 gene from the Candida albicans genome by sequentially replacing the entire coding region with the selectable markers ARG4 and HIS1. The results showed that the deletion of Ppt1 did not affect the hyphal formation of C. albicans under serum induction and caused enhanced sensitivity to DNA damage, Calcofluor white and salt-induced stress. We also found that Ppt1 was not required for the phenotypic response of cells treated with the genotoxins, methylmethane sulfonate and hydroxyurea. Flow cytometric analyses indicated that ppt1 Delta cells and wild-type cells showed similar G(2)/M arrest profiles when exposed to DNA damage stress. Ppt1 was not required for the activation of the DNA damage response pathway, as indicated by normal phosphorylation of Rad53 and Rfa2 in ppt1 Delta cells under DNA damage stress. We suggest that Ppt1 plays important roles in response to various stress conditions in C. albicans.