SUMOylation of the nuclear pore complex basket is involved in sensing cellular stresses

The nuclear pore complex (NPC) is the major conduit for nucleocytoplasmic transport and serves as a platform for gene regulation and DNA repair. Several nucleoporins undergo ubiquitylation and SUMOylation and these modifications play an important role in nuclear pore dynamics and plasticity. In this paper, we perform a detailed analysis of these post-translational modifications of yeast nuclear basket proteins under normal growth conditions as well as upon cellular stresses, with a focus on SUMOylation. We find that the balance between the dynamics of SUMOylation and deSUMOylation of Nup60 and Nup2 at the NPC deeply differs, particularly in G1 and S phase. While Nup60 is the unique target of genotoxic stress within the nuclear basket that likely belongs to the SUMO-mediated DNA damage response pathway, both Nup2 and Nup60 show a dramatic increase in SUMOylation upon osmotic stress, with Nup2 SUMOylation being enhanced in Nup60 SUMO-deficient mutant. Taken together, our data reveal that there are several levels of cross-talk between nucleoporins, and that the post-translational modifications of the NPC serve in sensing cellular stress signals.