GTPase Npa3‐ TORC1 crosstalk suggests genetic coordination of nutrient sensing and translational control

The GPN‐loop GTPase Npa3 plays a critical role in RNA polymerase II (RNAPII) assembly and nuclear import. We employed here the npa3 Δ C mutant, which supports normal RNAPII localization and function, to investigate potential links between Npa3 and target of rapamycin complex I (TORC1) signaling. The npa3 Δ C cells exhibited increased sensitivity to rapamycin, a synthetic sickness interaction with tor1 Δ, and a delayed growth recovery rate from rapamycin‐induced G1 arrest. Co‐expression analysis identified LTV1 , a gene involved in TORC1 signaling and ribosome nuclear export, as one of the top genes co‐expressed with NPA3 . Furthermore, overexpression of eukaryotic translation initiation factor 1A (eIF1A, TIF11 ) or regulator of heterotrimeric G‐protein signaling ( RGS2 ) restored growth in npa3 Δ C cells under rapamycin treatment. Interestingly, RGS2 also rescued growth under hygromycin B stress. Our findings suggest a genetic interplay between Npa3 and TORC1.