Production of chorismate mutase-prephenate dehydrogenase by a strain of Escherichia coli carrying a multicopy, tyrA plasmid. Isolation and properties of the enzyme

Rational Engineering of Chorismate-Related Pathways in Saccharomyces cerevisiae for Improving Tyrosol Production

Tyrosol is extensively used in the pharmaceutical industry as an important natural product from plants. In this study, an exogenous pathway involved in catalyzing tyrosine to tyrosol was introduced into Saccharomyces cerevisiae. Furthermore, The pyruvate decarboxylase gene pdc1 was deleted to redirect the flux distribution at the pyruvate node, and a bifunctional NAD⁺-dependent fused chorismate mutase/prephenate dehydrogenase from E. coli (EcTyrA) and its' tyrosine inhibition resistant mutant (EcTyrA^M53I/A354V) were heterologously expression in S. cerevisiae to tuning up the chorismate metabolism effectively directed the metabolic flux toward tyrosol production. Finally, the tyrosol yield of the engineered strain GFT-4 was improved to 126.74 ± 6.70 mg/g DCW at 48 h, increased 440 times compared with that of the control strain GFT-0 (0.28 ± 0.01 mg/g DCW). The new synergetic engineering strategy developed in this study can be further applied to increase the production of high value-added aromatic compounds derived from aromatic amino acid or shikimate in S. cerevisiae.

Chorismate mutase-prephenate dehydrogenase from Escherichia coli: spatial relationship of the mutase and dehydrogenase sites

The inhibition of the bifunctional enzyme chorismate mutase-prephenate dehydrogenase (4-hydroxyphenylpyruvate synthase) by substrate analogues has been investigated at pH 6.0 with the aim of elucidating the spatial relationship that exists between the sites at which each reaction occurs. Several chorismate and adamantane derivatives, as well as 2-hydroxyphenyl acetate and diethyl malonate, act as linear competitive inhibitors with respect to chorismate in the mutase reaction and with respect to chorismate in the mutase reaction and with respect to prephenate in the dehydrogenase reaction. The similarity of the dissociation constants for the interaction of these compounds with the free enzyme, as determined from the mutase and dehydrogenase reactions, indicates that the reaction of these inhibitors at a single site prevents the binding of both chorismate and prephenate. However, not all the groups on the enzyme, which are responsible for the binding of these two substrates, can be identical. At lower concentrations, citrate or malonate prevents reaction of the enzyme with prephenate, but not with chorismate. Nevertheless, the combining sites for chorismate and prephenate are in such close proximity that the diethyl derivative of malonate prevents the binding of both substrates. The results lead to the proposal that the sites at which chorismate and prephenate react on hydroxyphenylpyruvate synthase share common features and can be considered to overlap.