Snails and slugs can accumulate and detoxify heavy metals with the help of metallothioneins, small sulphur-rich proteins that can bind ions of heavy metals such as cadmium. Baumann et al. now report the solution structure of a metallothionein from the common periwinkle, a small species of sea snail that lives on the rocky shores of the Atlantic Ocean. In contrast to the two-domain structure of previously characterized metallothioneins, the protein forms a larger three-domain structure and can bind nine cadmium ions. By binding more metal atoms in this way, the snails can cope efficiently with heavy metals in their environment.
Angew. Chem. Int. Ed. 10.1002/anie.201611873 (2017).