Nsf1/Ypl230w participates in transcriptional activation during non-fermentative growth and in response to salt stress in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, fermentable carbon sources such as glucose and fructose are preferred and elicit glucose repression of genes needed to metabolize non-fermentable carbon sources such as glycerol, ethanol and acetate. Different sets of transcription factors are needed to adjust to specific carbon conditions. For example, Mig1 and Mig2 repress the transcription of gluconeogenic and respiratory genes in the presence of abundant glucose, while the transcriptional activation of these genes depends on transcription factors such as Adr1 and Cat8. Here we show that Ypl230w, which we renamed to Nsf1 (nutrient and stress factor 1), is expressed and localizes to the nucleus under non-fermentable carbon conditions to activate gene transcription. Specifically, the transcriptional activation of ACS1, CIT2 and IDH1 is shown to be partially dependent on intact NSF1. Similarly, the transcriptional activation of ENA1 is impaired in the nsf1Delta mutant in response to high concentrations of NaCl, implying that NSF1 is also needed for the yeast response to sodium stress. The carbon- and NaCl-mediated transcriptional activation of ENA1 is dependent on Nsf1. This finding implies that the yeast response to non-fermentable carbon and salt stress is at least partially dependent on NSF1.