Regulated gene expression in yeast

The present invention relates to methods and compositions for regulated expression of specific genes in . The invention can be used to identify and clone genes of interest and to identify antifungal agents using high-throughput screening techniques. The invention provides novel yeast cells comprising genes whose expression can be modulated by growth in the presence or absence of metal ions, methods for making such yeast cells, and methods of using such yeast cells for determining the requirement for expression of particular genes for the growth or viability of the yeast cells.