ABSTRACT
114Marine mussels (Mytilidae) are sessile bivalve mollusks that populate the highest wave-impact regions of rocky seashore habitats. A key to their evolutionary success in the intertidal environment is the byssus—a protein-based fibrous anchor that is fabricated by the mussel. The byssus is made up of numerous byssal threads, which are without hyperbole, the lifeline of the organism. Each byssal thread can be subdivided into three distinct functional elements—the core, the cuticle, and the plaque, which function as a self-healing shock-absorbing tether, an abrasion resistant coating, and a versatile underwater glue, respectively. A critical feature of each of these three elements is the presence of protein–metal coordination interactions that influence to a large degree the material properties. In particular, interactions between histidine and Zn/Cu contribute significantly to the deformation and self-healing behavior of the thread core, while interactions between 3, 4-dihydroxyphenylalanine and Fe enhance the mechanical function of the cuticle, as well as the formation and adhesive properties of the plaque. In the present chapter, we will provide a comprehensive overview of the state-of-the-art understanding of the role of protein–metal interactions in the material properties and formation of the byssus, while highlighting open questions.
