Mussel protein adhesion depends on interprotein thiol-mediated redox modulation

Mussel adhesion depends on secreted dopa-modified proteins, but the dopa groups are prone to oxidation, which decreases their stickiness. A second mussel protein is now shown to regulate the redox state of these adhesive groups by coupling thiol oxidation to dopa reduction. Mussel adhesion is mediated by foot proteins (mfps) rich in a catecholic amino acid, 3,4-dihydroxyphenylalanine (dopa), capable of forming strong bidentate interactions with a variety of surfaces. A tendency toward facile auto-oxidation, however, often renders dopa unreliable for adhesion. We demonstrate that mussels limit dopa oxidation during adhesive plaque formation by imposing an acidic, reducing regime based on the thiol-rich mfp-6, which restores dopa by coupling the oxidation of thiols to dopaquinone reduction.