Regulation of cystathionine gamma-lyase in Saccharomyces cerevisiae.
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.
Ono
B
B
Laboratory of Environmental Hygiene Chemistry, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Naito
K
K
Shirahige
Y
Y
Yamamoto
M
M
D003542:Cystathionine gamma-Lyase / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
D008715:Methionine; D003542:Cystathionine gamma-Lyase; D005978:Glutathione; D003545:Cysteine