Sulfur amino acid metabolism in Schizosaccharomyces pombe: occurrence of two O-acetylhomoserine sulfhydrylases and the lack of the reverse transfulfuration pathway

Abstract The fission yeast Schizosaccharomyces pombe has a unique organization of sulfur amino acid metabolism: it has two distinct O -acetylhomoserine sulfhydrylases (homocysteine synthases). Similar to Enterobacteriaceae, S. pombe lacks cystathionine β-synthase and cystathionine γ-lyase - the enzymes of the reverse transsulfuration pathway, by which methionine is readily metabolized to cysteine - a likely effector in the sulfur metabolite repression system. Consequently no repression of sulfate assimilation is observed when methionine is added to the growth medium.