Construction and application of novel feedback-resistant 3-deoxy-D-arabino-heptulosonate-7-phosphate synthases by engineering the N-terminal domain for L-phenylalanine synthesis

3-Deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHP synthase) encoded by aroF is the first enzyme of the shikimate pathway. In the present study, an AroF variant with a deficiency in residue Ile11 (named AroF*) was shown to be insensitive to l-tyrosine. According to three-dimensional structure analysis, nine AroF variants were constructed with truncation of different N-terminal fragments, and overexpression of the variants AroF((1-9)), AroF((1-10)), AroF((1-12)) and, in particular, AroF((1-11)) significantly increased the accumulation of l-phenylalanine (l-Phe). However, the AroG and AroH variants with similar truncations of the N-terminal fragments decreased the production of l-Phe. By co-overexpressing AroF((1-11)) and PheA(fbr), the production of l-Phe was increased from 2.36 +/- 0.07gL(-1) (co-overexpression of the wild-type AroF and PheA(fbr)) to 4.29 +/- 0.06gL(-1). The novel variant AroF((1-11)) showed great potential for the production of aromatic amino acids and their derivatives.