Cloning and Expression of aroG Gene of E. coli and Its Co-expression with pheA and tyrB Genes.

3-Deoxy-D-arabino-heptulonate-7-phosphate synthetase (DAHP) is one of the key enzymes in phenylalanine biosynthesis pathway. In E. coli, DAHP is encoded by aroG Gene. In this work, aroG was cloned from an E. coli mutant strain resistant to m-fluro-L-phenylalanine (mPF) and p-fluro-L-phenylalanine (pPF) by PCR. The gene was expressed under the control of lambda phage promoter p(R) in P2392 strain of E. coli. Distinct band was detected as the product of aroG on SDS-PAGE. The specific activity in crude extract of DAHP was raised to 1.7-fold. Based on the cloning and expression of pheA (encoding both chorsmate mutase CM and prephenate dehydratase PD) and tyrB (encoding phenylalanine aminotransferase PAT) genes, aroG, pheA and tyrB genes were constructed and expressed in P2392. The results showed that the specific activities of DAPH, CM/PD and PAT in crude extracts were increased by 1.7, 13.9/7.8 and 2.3-fold, respectively.