Aquatic proteins with repetitive motifs provide insights to bioengineering of novel biomaterials.

Proteins with repetitive motifs play vital structural and adhesive functions in nature. Some repeat proteins in particular have adapted to harsh aquatic surroundings to support the survival and reproduction of organisms. Significant effort has been made to identify aquatic repeat proteins with attractive properties and functions to be used as novel biomaterials. Examples of such proteins include matrix proteins from pearl oysters, minicollagens from sea anemones, cement proteins from sandcastle worms, and byssal proteins from marine mussels. Here, several repetitive motifs from aquatic proteins are reviewed, and their characteristic properties are linked to practical uses in three aspects of aquatic life: defense, shelter, and attachment. Some repetitive motifs interact with minerals and consequently generate strong outer cover of shells, and some motifs relate with sticky nature, which contribute to organisms' habitation by adhering themselves in harsh aquatic environments. Other motifs, such as silk- or collagen-like motifs, are also involved in structural rigidity as shown in mussel's byssus and egg membrane. Thus, understanding aquatic repetitive motifs will provide clues about biomedical and biotechnological applications of engineered biomaterials in wet environments.