A genetic approach to identify amino acids in human GCN1 required for mediating Gcn2 activation.

The conserved protein kinase GCN2 orchestrates cellular adaptation to amino acid starvation and other stress. Activation of GCN2 requires direct binding to its effector protein GCN1, via the RWDBD region in GCN1. In yeast, overexpression of the RWDBD, with or without the C-terminus (CTD), elicits a dominant-negative phenotype due to impairing Gcn1-Gcn2 interaction. Here we show that overexpressed human RWDBD+CTD also causes a dominant-negative phenotype in yeast, in a manner dependent on specific amino acids. All but one amino acid is conserved from yeast to human, suggesting conservation of the GCN2 binding parameters in GCN1, with minor evolutionary divergence.