YALI0C22088g from Yarrowia lipolytica catalyses the conversion of l-methionine into volatile organic sulfur-containing compounds.

The enzymatic conversion of l-methionine (l-Met) into volatile organic sulfur-containing compounds (VOSCs) plays an important role in developing the characteristic aroma of foods. However, the mechanism for the direct conversion of l-Met into VOSCs is still unclear in yeast cells used to make food products. Here, we show that the transcription profile of YALI0C22088g from Yarrowia lipolytica correlates positively with l-Met addition. YALI0C22088g catalyses the γ-elimination of l-Met, directly converting l-Met into VOSCs. YALI0C22088g also exhibits strong C-S lysis activities towards l-cystathionine and the other sulfur-containing compounds and forms a distinct cystathionine-γ-lyase subgroup. We identified eight key amino acid residues in YALI0C22088g, and we inferred that the size of the tunnel and the charges carried by the entrance amino acid residue are the determinants for the enzymatic conversion of l-Met into VOSCs. These findings reveal the formation mechanism of VOSCs produced directly from l-Met via the demethiolation pathway in Yarrowia lipolytica, which provides a rationale for engineering the enzymatic conversion of l-Met into VOSCs and thus stimulates the enzymatic production of aroma compounds.