Abstract 1185 Infection with P. aeruginosa ExoS, ExoT, and ExoY leads to phosphorylation of a PKA target without elevating cAMP

Gpr1 is a G protein-coupled receptor (GPCR) that plays a key role in nutrient sensing in yeast.It functions in glucose signaling, where it helps regulate the cAMP-PKA pathway, influencing cellular responses such as growth, metabolism, and cell differentiation.Gpr1 has a long intrinsically disordered region (IDR) primarily composed of asparagine residues in its intracellular loop 3 region, a region critical for the signaling of GPCRs.The function of the poly-N region in Gpr1 has not been examined.To investigate the role of this poly-N region, we generated yeast strains expressing Gpr1 lacking the poly-N region and compared their behaviors to those with full-length Gpr1.We used growth assays to measure cell proliferation and differentiation, and we performed western blot analysis to investigate the molecular effect of removing poly-N in Gpr1.Our results show that yeast cells that lacked this poly-N region in Gpr1 grew significantly slower than wild-type cells, showing the importance of this region in the optimal proliferation of cells.Deleting the poly-N region also decreases the level of invasive growth in haploid yeast cells.Molecular analysis showed the phosphorylation level of PKA substrates is lower in the poly-N mutants, indicating a role of this region in sustaining PKA activity.We conclude that an intact poly-N region is required for full functionality of Gpr1 in nutrient signaling and proper level of PKA activation.Our results offer novel insights into the mechanisms of GPCR regulation by IDR and further open doors toward future research into their broader functions in cell-signaling networks.