Author:

Abstract:

In a first selective screening, we have used the chemical compound Diverset from Chembridge Corporation to identify specific inhibitors of Candida albicans trehalose-6-phosphate phosphatase Tps2 by a growth assay. Deletion of Tps2 (enzyme which has no homolog in mammalian systems) reduces the survival of Candida cells in a mouse model (Van Dijck et al, 2002; Maidan et al., 2008). This first screening was done at high temperature, at which the tps2 homozygote can not grow and resulted in the identification of less than 70 compounds (out of 10 000), most of them with fungistatic activities. The specificity towards Tps2 turned out to be very low as most compounds also inhibited the growth of a wild type laboratory Candida strain. The fungicidal compounds were further tested against other Candida species, such as C. glabrata, C. krusei and C. parapsilosis (clinical isolates). Biofilm formation in vitro was also assayed in a 96-well plate set up: fungicidal compounds inhibited biofilm when added at the adhesion stage, and only one retained a fungicidal activity on mature biofilm (from 24h biofilm to 6-days old biofilm) formed by C. albicans but not by C. glabrata. Clusters of active compounds permitted the identification of potential known inhibitors by similarity search, one of these clusters showing some similarity to Hsp90 inhibitors for instance. The most potent compound did not share any similarity to known inhibitors, and its target or mode of action remains to be identified.