title: Mechanical homeostasis of a DOPA-enriched biological coating from mussels in response to metal variation.
abstract: Protein-metal coordination interactions were recently found to function as crucial mechanical cross-links in certain biological materials. Mussels, for example, use Fe ions from the local environment coordinated to DOPA-rich proteins to stiffen the protective cuticle of their anchoring byssal attachment threads. Bioavailability of metal ions in ocean habitats varies significantly owing to natural and anthropogenic inputs on both short and geological spatio-temporal scales leading to large variations in byssal thread metal composition; however, it is not clear how or if this affects thread performance. Here, we demonstrate that in natural environments mussels can opportunistically replace Fe ions in the DOPA coordination complex with V and Al. In vitro removal of the native DOPA-metal complexes with ethylenediaminetetraacetic acid and replacement with either Fe or V does not lead to statistically significant changes in cuticle performance, indicating that each metal ion is equally sufficient as a DOPA cross-linking agent, able to account for nearly 85% of the stiffness and hardness of the material. Notably, replacement with Al ions also leads to full recovery of stiffness, but only 82% recovery of hardness. These findings have important implications for the adaptability of this biological material in a dynamically changing and unpredictable habitat.
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam 14424, Germany.
authors: Clemens N Z
authors: CN
authors: Schmitt
authors: Institute of Chemistry, University of Potsdam, Potsdam 14476, Germany.
authors: Alette
authors: A
authors: Winter
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam 14424, Germany.
authors: Luca
authors: L
authors: Bertinetti
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam 14424, Germany.
authors: Admir
authors: A
authors: Masic
authors: Institute of Chemistry, University of Potsdam, Potsdam 14476, Germany.
authors: Peter
authors: P
authors: Strauch
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam 14424, Germany matt.harrington@mpikg.mpg.de.
authors: Matthew J
authors: MJ
authors: Harrington
mesh_terms: D000535:Aluminum / Q000378:metabolism*; D000818:Animals; D004295:Dihydroxyphenylalanine / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D049878:Mytilus / Q000378:metabolism*
chemical_list: D004295:Dihydroxyphenylalanine; D000535:Aluminum; D007501:Iron
keywords: DOPA; coating; metal coordination; mussel byssus