Comparative analysis of mussel foot protein 3B co-expressed with tyrosinases provides a potential adhesive biomaterial

Mussel foot proteins (Mfps), which help mussels attach to various surfaces, are considered to be promising biomaterials due to their outstanding adhesive properties. However, limited production and lack of post-translational modifications of tyrosine residues into 3,4-dihydroxyphenylalanine (Dopa) in bacterial expression systems have hampered their applications. In the present study, for the first time we established the expression of recombinant Mytilus galloprovincialis foot protein type 3 variant B (fp-3B) in Escherichia coli; and achieved its viable production (~51 mg/L). Additionally, the Dopa content and adhesive properties of fp-3B co-expressed using various types of tyrosinases were compared. Consequently, the co-expression of fp-3B construct together with tyrosinase from Verrucomicrobium spinosum (TyrVs) yielded up to 87 mg/L of modified fp-3B; hydroxylation of tyrosine residues accounted for 57.18% by acid-borate difference spectroscopy. The modified fp-3B also showed significant coating and adhesive ability, and its bulk-scale adhesive strength was 2.9-fold higher than that of unmodified fp-3B. Compared with other type 3 mussel foot proteins, the high-yield expression and extensive hydroxylation level of the recombinant protein indicate that fp-3B co-expressed with TyrVs (3B-Vs) has the potential to be widely used as bioglues.