Yeast Gcn2 retains activity following humanization of its auto-phosphorylation region

The protein kinase Gcn2 is a conserved component of a eukaryotic signaling pathway best known for helping cells cope with amino acid shortage. Upon starvation, Gcn2 auto-phosphorylates and then phosphorylates eIF2α, triggering widespread changes in gene expression. While Gcn2 is gaining attention for its diverse biological roles and links to various diseases, its activation and regulation remain unclear. To date, Saccharomyces cerevisiae remains an important model for dissecting these mechanisms in detail. However, commercial antibodies recognizing phosphorylated Gcn2 are available only for mammalian GCN2. Therefore, we engineered a yeast Gcn2 variant, Gcn2-HsC, recognizable by these antibodies. Gcn2-HsC almost completely complemented a gcn2Δ strain, retained its ability to phosphorylate eIF2α, and is still dependent on Gcn1 for function. Ultimately, our results suggest that Gcn2-HsC serves as a valuable tool for Gcn2-related studies in the highly tractable yeast system.