Hy. Sohn et H. Kuriyama, The role of amino acids in the regulation of hydrogen sulfide production during ultradian respiratory oscillation of Saccharomyces cerevisiae, ARCH MICROB, 176(1-2), 2001, pp. 69-78
We previously demonstrated that periodic H2S production during aerobic cont
inuous culture of Saccharomyces cerevisiae resulted in ultradian respirator
y oscillation, and that H2S production was dependent on the activity of sul
fate uptake and the level of sulfite. To investigate the mechanism of regul
ation of the sulfate assimilation pathway and of respiratory oscillation, s
everal amino acids were pulse-injected into cultures during respiratory osc
illation. Injection of sulfur amino acids or their derivatives perturbed re
spiratory oscillation, with changes in the H2S production profile. Four maj
or regulators of H2S production in the sulfate assimilation pathway and res
piratory oscillation were identified: (1) O-acetylhomoserine, not O-acetyls
erine, as a sulfide acceptor, (2) homoserine/ threonine as a regulator of O
-acetylhomoserine supply, (3) methionine/S-adenosyl methionine as a negativ
e regulator of sulfate assimilation, and (4) cysteine (or its derivatives)
as an essential regulator. The results obtained after the addition Of DL-pr
opargylglycine (5 muM and 100 muM) and cystathionine (50 muM) suggested tha
t the intracellular cysteine level and cystathionine gamma -lyase, rather t
han methionine/S-adenosylmethionine, play an essential role in the regulati
on of sulfate assimilation and respiratory oscillation. Based on these resu
lts and those of our previous reports, we propose that periodic depletion o
f cysteine (or its derivatives), which is involved in the detoxification of
toxic materials originating from respiration, causes periodic H2S producti
on.