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A tyrosinase enzyme TyrVs

Introduction

Tyrosinase is a copper-containing oxidoreductase that possesses two catalytic activities, and is involved in the first few steps of melanin synthesis from l-tyrosine. As shown in Fig. 1, tyrosinase catalyzes the ortho-hydroxylation of l-tyrosine to l-DOPA via its monophenolase (MP) activity, and consecutively oxidizes l-DOPA to l-dopaquinone via the diphenolase (DP) activity, thereby consuming oxygen. l-dopaquinone is not stable and will be further non-enzymatically oxidized to l-dopachrome (a red-colored product) in the presence of O₂.TyrVs refers to a tyrosinase enzyme derived from Verrucomicrobium spinosum, which plays a critical role in the hydroxylation of tyrosine residues into L-Dopa. This enzyme has shown efficient activity, particularly in the context of biological adhesion, as demonstrated in studies co-expressing mussel foot protein 3 with TyrVs.

Fig. 1 | Synthesis scheme of L-DOPA and further oxidized product L-dopachrome.

Usage and Biology

In our project, TyrVs can catalyze the tyrosine residues in the TRn4-mfp5 protein, converting them into L-DOPA, thereby enhancing its adhesive properties. L-DOPA exhibits excellent adhesion, particularly in moist environments. This transformation process is similar to the mechanism used by marine organisms like mussels, which enhance their adhesion through L-DOPA.

Characterization

To validate the functionality of the tyrosinase TyrVs, we designed bacteria expressing TyrVs.We constructed the pET-SUMO-TyrVs vector, after culturing at 16°C for 20 hours, extracted the proteins for SDS-PAGE and Coomassie Brilliant Blue staining analysis.

Fig. 2 | Expression of recombinant TyrVs in E. coliBL21 (DE3) with pET-PC-SUMO-TyrVs.

Lane 1: Marker. lanes 2 to 4: whole-cell lysate, supernatant and pellet from induced cells with 0.5 mM IPTG respectively;lanes 5 to 7: whole-cell lysate, supernatant and pellet from induced cells respectively.

Fig. 3 | SDS-PAGE analysis of protein fractions eluted from the Ni-NTA column.

Lane 1: Marker. Lane 2: Lysis Buffer. Lane 3: Supernatant. Lane 4: 20 mM Imidazole. Lane 5: 50 mM Imidazole. Lane 6: 150 mM Imidazole.

Fig. 4 | The activity assay results of tyrosinase TyrVs

a-b.Michaelis-Menten plot and Lineweaver-Burk double reciprocal plot of enzymatic reaction from tyrosine to dopaquinone experiments. c-d.Michaelis-Menten plot and Lineweaver-Burk double reciprocal plot of enzymatic reaction from L-DOPA to dopaquinone experiments.

Reference

#TAN D, ZHAO J P, RAN G Q, et al. Highly efficient biocatalytic synthesis of L-DOPA using in situ immobilized Verrucomicrobium spinosum tyrosinase on polyhydroxyalkanoate nano-granules [J]. Appl. Microbiol. Biotechnol., 2019, 103(14): 5663-78.
#YAO L, WANG X, XUE R, et al. Comparative analysis of mussel foot protein 3B co-expressed with tyrosinases provides a potential adhesive biomaterial [J]. Int. J. Biol. Macromol., 2022, 195: 229-36.

Sequence and Features