Novel mutations in the pheA gene of Escherichia coli K-12 which result in highly feedback inhibition-resistant variants of chorismate mutase/prephenate dehydratase.

ABSTRACT: The bifunctional enzyme chorismate mutase/prephenate dehydratase (EC 5.4.99.5/4.2.1.51), which is encoded by the pheA gene of Escherichia coli K-12, is subject to strong feedback inhibition by L-phenylalanine. Inhibition of the prephenate dehydratase activity is almost complete at concentrations of L-phenylalanine greater than 1 mM. The pheA gene was cloned, and the promoter region was modified to enable constitutive expression of the gene on plasmid pJN302. As a preliminary to sequence analysis, a small DNA insertion at codon 338 of the pheA gene unexpectedly resulted in a partial loss of prephenate dehydratase feedback inhibition. Four other mutations in the pheA gene were identified following nitrous acid treatment of pJN302 and selection of E. coli transformants that were resistant to

SUBMITTER: Nelms J 

PROVIDER: S-EPMC195826 | biostudies-literature | 1992 Aug

REPOSITORIES: biostudies-literature