Putative cysteine synthase that catalyzes the conversion of O-acetyl-L-serine (OAS) into cysteine, the last step in the cysteine biosynthesis pathway. However, in contrast to cysteine synthase cys11, this CS-like protein seems not to function in cysteine biosynthesis, at least under normal growth conditions, although the transcript is produced. hydrogen sulfide + O-acetyl-L-serine = acetate + L-cysteine Belongs to the cysteine synthase/cystathionine beta-synthase family.