Genome-wide Screening For Genes Involved In Calcium Homeostasis In Budding Yeast

In eukaryotic cells, the calcium ion (Ca²⁺) functions as a ubiquitous intracellular messenger regulating a myriad of biological processes such as cell proliferation, muscle contraction, programmed cell death. Calcium homeostasis is highly regulated to maintain Ca²⁺ levels within optimal concentration ranges in the cytosol and other organelles. In yeast, there are also many unknown mechanisms to be unidentified in the Ca²⁺ homeostasis system, so we screen the genes related to Ca²⁺ signaling pathway via a high-throughput experiment. A detailed knowledge of calcium homeostasis systems will likely contribute to new, more effective drug therapies for the treatment of fungal disease, as well as autoimmune and neurodegenerative disorders.From a genome-scale genetic screen, we have identified 37 calcium-sensitive gene mutations in Saccharomyces cerevisiae. We find that twelve mutations are strongly sensitive to calcium and ten mutations are moderately sensitive to calcium. Functional analysis indicates that 26% of these identified genes are involved in the vacuolar protein sorting (VPS) pathway, 14% in the PHO pathway, 14% in response to high osmolar stress, and 11% in the regulation of V-ATPase function. In addition, 30% of gene products locate in the cytoplasm, 15% in the vacuole, 12% in the nucleus,and 9% in ER. We have also examined the whole-cell Ca²⁺ contents of the 37 deletion strains and found that the whole-cell Ca²⁺ contents of 9 strains are 1.5 times higher than that of the wild type BY4743.