A Yeast Global Genetic Screen Reveals that Metformin Induces an Iron Deficiency-Like State

We report here a simple and global strategy to map out gene functions and target pathways of drugs, toxins or other small molecules based on “homomer dynamics” Protein-fragment Complementation Assays ( hd PCA). hd PCA measures changes in self-association (homomerization) of over 3,500 yeast proteins in yeast grown under different conditions. hd PCA complements genetic interaction measurements while eliminating confounding effects of gene ablation. We demonstrate that hd PCA accurately predicts the effects of two longevity and health-span-affecting drugs, immunosuppressant rapamycin and type II diabetes drug metformin, on cellular pathways. We also discovered an unsuspected global cellular response to metformin that resembles iron deficiency. This discovery opens a new avenue to investigate molecular mechanisms for the prevention or treatments of diabetes, cancers and other chronic diseases of aging.