Metabolic Engineering of Escherichia coli for l -Tyrosine Production by Expression of Genes Coding for the Chorismate Mutase Domain of the Native Chorismate Mutase-Prephenate Dehydratase and a Cyclohexadienyl Dehydrogenase from Zymomonas mobilis

Abstract

ABSTRACT The expression of the feedback inhibition-insensitive enzyme cyclohexadienyl dehydrogenase (TyrC) from Zymomonas mobilis and the chorismate mutase domain from native chorismate mutase-prephenate dehydratase (PheA CM ) from Escherichia coli was compared to the expression of native feedback inhibition-sensitive chorismate mutase-prephenate dehydrogenase (CM-TyrA p ) with regard to the capacity to produce l -tyrosine in E. coli strains modified to increase the carbon flow to chorismate. Shake flask experiments showed that TyrC increased the yield of l -tyrosine from glucose ( Y l -Tyr/Glc ) by 6.8-fold compared to the yield obtained with CM-TyrA p . In bioreactor experiments, a strain expressing both TyrC and PheA CM produced 3 g/liter of l -tyrosine with a Y l -Tyr/Glc of 66 mg/g. These values are 46 and 48% higher than the values for a strain expressing only TyrC. The results show that the feedback inhibition-insensitive enzymes can be employed for strain development as part of a metabolic engineering strategy for l -tyrosine production.