Inhibitory Effects of Broccoli Sprouts (Brassica oleracea L.) Extract on MET6 Expression levels and Growth Dynamics in Saccharomyces Cerevisiae

Methionine and cysteine are essential sulfur-containing amino acids that play critical roles in cellular metabolism. Methionine functions as the initiating residue in eukaryotic protein synthesis and is activated through S-adenosylmethionine. In fungi, methionine biosynthesis is mediated by the cobalamin-independent methionine synthase MET6. Biological systems assimilate sulfur by first reducing inorganic sulfate, a necessary step before it can be incorporated into amino acids, contrasting with the chemical synthesis route used for most industrial methionine. This study examined whether natural organosulfur-rich sources, specifically broccoli sprout extract, influence methionine biosynthesis in S. cerevisiae. MET6 gene expression was quantified by qRT-PCR in wild-type BY4742 and met15Δ mutant strains following treatment with broccoli sprout extract. Two-way ANOVA revealed significant downregulation of MET6 expression after two h of exposure. Consistent with reduced transcription, overall cell growth declined in both strains compared with untreated controls, this study demonstrates that broccoli-derived organosulfur compounds can significantly downregulate the expression of the key methionine biosynthesis gene MET6 in S. cerevisiae.