Biochemical characterization of a novel tyrosine phenol-lyase from Fusobacterium nucleatum for highly efficient biosynthesis of l-DOPA

Tyrosine phenol-lyase (TPL) catalyzes the reversible cleavage of l -tyrosine to phenol, pyruvate and ammonia. When pyrocatechol is substituted for phenol, l -dihydroxyphenylalanine ( l -DOPA) is produced. The TPL-catalyzed route was regarded as the most economic process for l -DOPA production. In this study, a novel TPL from Fusobacterium nucleatum ( Fn -TPL) was successfully overexpressed in Escherichia coli and screened for l -DOPA synthesis with a specific activity of 2.69   U   mg −1 . Fn -TPL was found to be a tetramer, and the optimal temperature and pH for α, β-elimination of l -tyrosine was 60   °C and pH 8.5, respectively. The enzyme showed broad substrate specificity toward natural and synthetic l -amino acids. Kinetic analysis suggested that the k cat / K m value for l -tyrosine decomposition was much higher than that for l -DOPA decomposition, while Fn -TPL exhibited similar catalytic efficiency for synthesis of l -tyrosine and l -DOPA. With whole cells of recombinant E. coli as biocatalyst, l -DOPA yield reached 110   g   L −1 with a pyrocatechol conversion of 95%, which was comparable to the reported highest level. The results demonstrated the great potential of Fn -TPL for industrial production of l -DOPA.