Pof1p may be involved in substrate recognition during ubiquitin SC79 cost marking because it interacts physically with an E2 ubiquitin conjugating enzyme, Ubc7p, and it is important in the unfolded protein response. Δpof1 cells were more sensitive to reductive stress than the Δubc7 cells (cells in which Ubc7p is absent), this last a well-characterized protein that participates in the ERAD-C pathway. A possible substrate

would be the MAP kinase molecule Kss1p, which interacts physically with Pof1p [19]. As mentioned above, Kss1p is a kinase involved in the control of filamentous growth and the pheromone response. Fasolo et al. (2011) observed that Δpof1 cells are defective in invasive growth and pseudohyphal growth. We hypothesize that the phenotype observed in Δpof1 cells PF-6463922 is due to the absence of stability regulation of Kss1p exerted by Pof1p. Therefore, the results described here showed that a protein involved in the yeast-to-hyphal transition

[19] possesses ATPase activity and is important in the response of yeast to various stresses. A study on gene expression modulation during yeast filamentous-form growth showed an enriched number of genes involved in protein quality control, such as N-linked glycosylation, ubiquitin-dependent protein catabolism and ER to Golgi transport. Moreover, this study pinpointed the 26S proteasome as an important component in the regulation of S. cerevisiae filamentous Forskolin growth [39]. The yeast-to-hyphal transition is a response of several fungi to stressful conditions. For the majority of pathogenic fungi, this transformation is an essential step in their infectious process, and modifications in plasma membrane and cell wall constituents have been implicated [40, 41]. The mechanisms that trigger the transition to filamentous growth in S. cerevisiae are associated with carbon or nitrogen stresses [39, 42]. The interplay between the filamentation process and protein quality control may be an important feature that deserves to be further investigated.

Conclusions This study characterized the molecular function of Pof1p as an ATPase involved in protein quality control. Pof1p was important to yeast defense against oxidative, heat shock and chemically induced stress. Several protein quality control components are still poorly described, despite their importance in neurological diseases. The molecular characterization of the components in yeast can be useful to understand the function of conserved human CB-5083 price proteins. Methods Chemicals: t-BOOH, tunicamycin and DTT were purchased from Sigma Chemical Company (St. Louis, MO, USA). The other chemicals used were analytical grade or better. H2O2 (30%) was obtained from Merck. Yeast strains and growth conditions: The yeast strains used here were obtained from the Yeast Deletion Clones repository (Invitrogen – Carlsbad, CA, USA).