Increased resistance to currently used antifungal compounds and the fact that these agents are often harmful to man and environment have resulted in a growing demand for new antifungals, which selectively act on cellular processes that are unique to fungi. To meet this demand, we have established a luciferin/luciferase based reporter system for high-throughput screening of extracts obtained from natural sources. This system allows us to identify compounds that specifically target fungal cell wall biosynthesis. It has been well established in the yeast Saccharomyces cerevisiae that cell wall synthesis is a highly dynamic process, which is orchestrated by the cell wall integrity (CWI) pathway. Such CWI pathway is also present in the filamentous fungus Aspergillus niger and probably widespread among fungi. We have previously shown that transcription of the A. niger agsA gene, encoding an alpha-1,3-glucan synthase, is strongly and specifically up-regulated in response to cell wall stress . We have also shown that the induced expression of the agsA gene is mediated via the RlmA transcription factor and its putative RlmA binding site within the agsA promoter . We are here presenting results for a new cell wall stress responsive A. niger reporter strain obtained by cloning a modified agsA promoter containing two additional RlmA binding motifs in front of a codon optimized luciferase gene . The performance of the system was verified by screening several antifungal compounds with a known mode of action. The specific response dynamics of the new reporter system will allow us to identify new putative antifungal compounds from natural extracts.
Full conference title:
9th EUROPEAN CONFERENCE ON FUNGAL GENETICS
- ECFG 9th (2008)