Baker's yeast as a tool for the development of antifungal kinase inhibitors--targeting protein kinase C and the cell integrity pathway

Today, the yeast Saccharomyces cerevisiae is probably the best-studied eukaryotic organism. This review first focuses on the signaling process which is mediated by the unique yeast protein kinase C (Pkc1p) and a downstream mitogen-activated protein kinase (MAPK) cascade. This pathway ensures cellular integrity by sensing cell surface stress and controlling cell wall biosynthesis and progression through the cell cycle. The domain structure of Pkc1p is conserved from yeast to humans. A yeast system for heterologous expression of specific domains in a chimeric yeast/mammalian PKC enzyme ("domain shuffling") is depicted. It is also proposed how this system could be employed for the study of protein kinase inhibitors in high-throughput screens. Moreover, a reporter assay that allows a quantitative readout of the activity of the cell integrity signaling pathway is introduced. Since a variety of protein kinases take part in the signal transduction, this broadens the range of targets for potential inhibitors.