In Synechococcus PCC7942, the smt locus is responsible for tolerance to zinc and cadmium. This was verified by deletion of the smt locus, which caused a reduction in zinc/cadmium tolerance (Turner et al., 1993). In the smt locus, there are two divergently transcribed genes, smtA and smtB. The smtA gene encodes class II metallothionein (56 amino acid… (More)