Regulation of cystathionine gamma-lyase in Saccharomyces cerevisiae

• Published in: Yeast (Chichester, England) Vol. 7; no. 8; p. 843
• Main Authors: Ono, B, Naito, K, Shirahige, Y, Yamamoto, M
• Format: Journal Article
• Language: English
• Published: England 01.11.1991
• Subjects: Cystathionine gamma-Lyase - metabolism; Cysteine - metabolism; Glutathione - metabolism; Methionine - metabolism; Saccharomyces cerevisiae - enzymology
• ISSN: 0749-503X
• DOI: 10.1002/yea.320070809

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.