Catalyzes the transformation of cystathionine to homocysteine. H2O + L,L-cystathionine = L-homocysteine + NH4(+) + pyruvate an S-substituted L-cysteine + H2O = a thiol + NH4(+) + pyruvate Amino-acid biosynthesis; L-methionine biosynthesis via de novo pathway; L-homocysteine from L-cystathionine: step 1/1. Cells lacking this gene show methionine prototrophy, suggesting that additional methionine biosynthetic pathway can be present in C.glutamicum. The mutant strains also completely lose their ability to show resistance to the S-(beta-aminoethyl)-cysteine, which is a toxic lysine analog. Belongs to the class-II pyridoxal-phosphate-dependent aminotransferase family. MalY/PatB cystathionine beta-lyase subfamily.