Regulation of cystathionine γ‐lyase in Saccharomyces cerevisiae

Abstract

Regulation of the two enzymes in reverse trans-sulfuration was investigated in Saccharomyces cerevisiae. In wild-type strains, cystathionine gamma-lyase, but not cystathionine beta-synthase, was depressed nearly 15-fold if cells were starved for both inorganic and organic sulfur compounds. In a met17 strain which is defective of O-acetylserine and O-acetylhomoserine sulfhydrylase, the same enzyme was derepressed if organic sulfur compounds were limited; the repressive effect was in the order of glutathione greater than methionine greater than cysteine. The repressive effect of methionine was not observed, however, in a cys2 cys4 strain which is deficient of serine O-acetyltransferase and cystathionine beta-synthase, indicating that methionine itself is not the effector. The weak repressive effect of cysteine was attributed to inefficient uptake of this amino acid. Our observations indicate that cystathionine gamma-lyase is the target of regulation in reverse trans-sulfuration and that cysteine is very likely to be the effector of this regulation.

Involvement of the VDE Homing Endonuclease and Rapamycin in Regulation of the Saccharomyces cerevisiae GSH11 Gene Encoding the High Affinity Glutathione Transporter

“…SD medium is a synthetic minimal medium (25). Sulfur-free (SF) medium was prepared by substituting all sulfate salts in SD medium with the corresponding chloride salts (26). To provide for the nutritional requirements of the strains used in this study, adenine (20 g/ml), lysine (30 g/ml), histidine (20 g/ml), leucine (30 g/ml), tryptophan (20 g/ml), and uracil * The work was carried out as a part of the Bio-Venture project and the 21st century Center of Excellence (COE) program of Ritsumeikan University.…”

Sulfur Transfer through an Arbuscular Mycorrhiza

“…Both positive and negative global regulatory proteins have been discovered in Neurospora crassa, Aspergillus nidulans, and S. cerevisiae that share homology at the protein level (Marzluf, 1997). In N. crassa and S. cerevisiae, the expression of the S assimilatory genes is almost completely absent in the presence of Cys or Met and is greatly reduced by glutathione (GSH) addition (Ono et al, 1991(Ono et al, , 1999Marzluf, 1997). These same enzymes in A. nidulans, on the other hand, are not down-regulated in response to S metabolites (Clarke et al, 1997;Sienko and Paszewski, 1999;Natorff et al, 2003).…”

Substrate Inhibition ofL-Cysteine α,β-Elimination Reaction Catalyzed byL-Cystathionine γ-Lyase ofSaccharomyces cerevisiae

“…25,26) However, the possibility that cysteine regulates the activity of CTT g-lyase, probably by removing the cofactor, can not be excluded.…”