Crm1 (XpoI) dependent nuclear export of the budding yeast transcription factor yAP‐1 is sensitive to oxidative stress

Background The yAP‐1 transcription factor is crucial for the oxidative stress response of the budding yeast Saccharomyces cerevisiae; its activity is induced in response to oxidative stress, and as a consequence the expression of a number of target genes is enhanced. We have shown previously that yAP‐1 is mainly found in the cytoplasm, but that upon the imposition of oxidative stress it localizes to the nucleus. In this study, we addressed the mechanism through which yAP‐1 nuclear localization is regulated. Results Here we show that yAP‐1 localization is mediated by active export from the nucleus, resulting from the activity of Crm1 (XpoI), a conserved protein that functions as an export receptor which recognizes the nuclear export signal (NES). When Crm1 expression was repressed, yAP‐1 was localized in the nucleus and induced the expression of a yAP‐1 dependent target gene. Our results also suggest that the cysteine rich domain (CRD), at the C‐terminus of yAP‐1, functions as an export recognition sequence. yAP‐1 and Crm1 interact in vivo and this interaction is reduced in response to oxidative stress. Conclusions These results suggest a novel regulatory mechanism of nucleocytoplasmic transport which is dependent upon a redox sensitive nuclear export pathway.