Redox capacity of an extracellular matrix protein associated with adhesion in Mytilus californianus

TitleRedox capacity of an extracellular matrix protein associated with adhesion in Mytilus californianus
Publication TypeJournal Article
Year of Publication2016
AuthorsNicklisch SCT, Spahn JE, Zhou H, Gruian CM, J. Waite H
JournalBiochemistry
Volume55
Pagination2022-2030
Date Published2016/04
ISBN Number0006-2960
Accession NumberWOS:000373656200009
Abstract

Adhesive mussel foot proteins (Mfps) rely in part on DOPA (3,4-dihydroxyphenyl-l-alanine) side chains to mediate attachment to mineral surfaces underwater. Oxidation of DOPA to Dopaquinone (Q) effectively abolishes the adsorption of Mfps to these surfaces. The thiol-rich mussel foot protein-6 (Mfp-6) rescues adhesion compromised by adventitious DOPA oxidation by reducing Q back to DOPA. The redox chemistry and kinetics of foot-extracted Mfp-6 were investigated by using a nonspecific chromogenic probe to equilibrate with the redox pool. Foot-extracted Mfp-6 has a reducing capacity of ∼17 e– per protein; half of this comes from the cysteine residues, whereas the other half comes from other constituents, probably a cohort of four or five nonadhesive, redox-active DOPA residues in Mfp-6 with an anodic peak potential ∼500 mV lower than that for oxidation of cysteine to cystine. At higher pH, DOPA redox reversibility is lost possibly due to Q scavenging by Cys thiolates. Analysis by one- and two-dimensional proton nuclear magnetic resonance identified a pronounced β-sheet structure with a hydrophobic core in foot-extracted Mfp-6 protein. The structure endows redox-active side chains in Mfp-6, i.e., cysteine and DOPA, with significant reducing power over a broad pH range, and this power is measurably diminished in recombinant Mfp-6.

DOI10.1021/acs.biochem.6b00044
Short TitleBiochemistry
Student Publication: 
No
Research Topics: 
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