Yippee-like protein Moh1 links gene expression to metabolism and selective stress resistance in Saccharomyces cerevisiae

The Yippee-like (YPEL) proteins are a conserved eukaryotic gene family implicated in proliferation, senescence, and stress adaptation. In humans, five paralogs (YPEL1-YPEL5) are widely expressed and encode proteins with high sequence and amino acid similarity, yet the molecular basis of their functions remains poorly defined. While conservation implies possible functional redundancy, the distinct roles of each YPEL paralog have not been defined. The budding yeast S. cerevisiae possesses a single ortholog, MOH1, which contributes to survival and stress responses and can be functionally complemented by human YPELs. However, the cellular role of MOH1 remains to be elucidated. Here, we investigated the function of MOH1 in S. cerevisiae. MOH1 deletion (moh1{Delta}) conferred sensitivity to sodium azide and sulfuric acid but increased resistance to hydrogen peroxide and acetic acid. Moh1 protein levels decreased upon hydrogen peroxide treatment and increased following sulfuric acid exposure, indicating stress-dependent regulation. Light and scanning electron microscopy showed that moh1{Delta} cells are constitutively rounder, tend to form clumps, and exhibit rough surface features, indicating altered cellular architecture. RNA profiling and FTIR spectroscopy revealed transcriptional reprogramming and metabolic remodeling in moh1{Delta} cells, including alterations in lipid, protein, and cell wall polysaccharide levels and composition. Intracellular ROS assays indicated that hydrogen peroxide resistance can be attributed to decreased cellular uptake resulting from altered permeability, rather than changes in mitochondrial ROS production. Collectively, our findings identify Moh1 as a regulatory factor linking gene expression to metabolism and cellular architecture, influencing membrane permeability and conferring selective stress resistance in S. cerevisiae.