Heterologous expression and characterization of soluble recombinant 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase from Actinosynnema pretiosum ssp. auranticum ATCC31565 through co-expression with Chaperones in Escherichia coli.

3-Deoxy-d-arabino-heptulosonate-7-phosphate synthase (DAHPS), (EC 2.5.1.54) catalyzes the first step of the shikimate pathway, the route for the biosynthesis of aromatic compounds in plants and microbes. In Actinosynnema pretiosum, the aroF gene (GenBank: AF056968.1) encodes DAHPS to condensate phosphoenolpyruvate (PEP) and d-erythrose 4-phosphate (E4P) to generate DAHP. In this study, a recombinant pET28a-aroF plasmid was constructed and A. pretiosum DAHPS was successfully expressed in soluble form by co-expression with chaperonins GroEL/GroES in Escherichia coli. The purification and kinetic characterization of the expressed protein were then investigated. The DAHPS originated from A. pretiosum demonstrated a pronounced substrate inhibition by PEP but was not sensitive to E4P. The purified enzyme was completely inactivated by EDTA but potently activated by several bivalent metal ions, especially Mn(2+) and Co(2+).