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

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.