This family consists of O-succinylhomoserine (thiol)-lyase, one of three different enzymes designated cystathionine gamma-synthase and involved in methionine biosynthesis. In all three cases, sulfur is added by transsulfuration from Cys to yield cystathionine rather than by a sulfhydrylation step that uses H2S directly and bypasses cystathionine. [Amino acid biosynthesis, Aspartate family]
Jiyao W et al.(2023). "The conserved domain database in 2023.",