aroG encodes a 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase isoform (also known as 2-dehydro-3-deoxyphosphoheptonate aldolase), which catalyzes the first committed and rate-limiting step of the shikimate pathway by condensing phosphoenolpyruvate and erythrose 4-phosphate to form DAHP [342, 343, 351, 360]. Native AroG activity is subject to feedback inhibition by aromatic amino acids; consequently, expression of feedback-resistant variants has been widely employed to increase intracellular aromatic precursor availability and to enhance tyrosine and downstream flavonoid production in Escherichia coli [351, 360].
In particular, the feedback-resistant mutant aroGfbr (D146N) exhibits high thermostability and has been overexpressed to increase carbon flux from glucose toward phenylpyruvate, L-phenylalanine [350], or L-DOPA accumulation [342].