Sulfur metabolism in hemiascomycetes yeast

Abstract

Sulfur metabolism is a central function of the cell. It has been extensively studied in the model yeast Saccharomyces cerevisiae. A comparative genomic study carried out across the hemiascomycetes clade has shown that S. cerevisiae displayed specificities not shared by the other yeast species. For instance, an O-acetylserine pathway was shown to be present in many yeast species. The complex regulatory pathways seem also to be conserved, with the exception of MET28, whose presence seems to be restricted to S. cerevisiae and related species. In order to explore this pathway in two distant yeast species, Kluyveromyces lactis and Yarrowia lipolytica, transcriptomic and metabolomic studies have been carried out in different conditions of sulfur supply. These high-throughput techniques allowed confirmation of the data of the comparative genomics but also the investigation of new components and new functions linked to sulfur metabolism, for instance, the role of the O-acetylserine pathway in cysteine biogenesis and the role of the aminotransferases in the degradation of methionine were confirmed. The screening of the pools of metabolic intermediates affected by the sulfur supply allowed the identification of new components of the pathway in Y. lipolytica such as taurine and hypotaurine, which seemed to play a role of sulfur storage. These methods also allowed the identification of the set of transporters involved in sulfur metabolism. Eventually, the comparison of these results with the data accumulated in the model S. cerevisiae highlighted the large-scale conservation of this pathway but also the large diversity in the regulated steps inside the pathway