Tat-Dependent Heterologous Secretion of Recombinant Tyrosinase by Pseudomonas fluorescens Is Aided by a Translationally Fused Caddie Protein.

Tyrosinase is a monooxygenase that catalyzes both the hydroxylation of -hydroxyphenyl moieties to -catechols and the oxidation of -catechols to -quinones. Apart from its critical functionality in melanogenesis and the synthesis of various neurotransmitters, this enzyme is also used in a variety of biotechnological applications, most notably mediating covalent cross-linking between polymers containing -hydroxyphenyl groups, forming a hydrogel. Tyrosinases from the genus are usually secreted as a complex with their caddie protein. In this study, we report an increased secretion efficiency observed when the tyrosinase gene was introduced into along with its caddie protein gene , which has the DNA sequence for the Tat (twin-arginine translocation) signal. We observed that the extracellular tyrosinase secretion level was even higher in its nonnatural translationally conjugated fusion protein form than in the natural complex of two separated polypeptides. The results of this study demonstrate that tyrosinase-expressing can be a stable source of bacterial tyrosinase through exploiting the secretory machinery of .