The
enzyme 5-enolpyruvylshikimate-3-phosphate (
EPSP) synthase catalyzes the sixth step of the seven-step
shikimate pathway. Chorismate, the product of the pathway, is a precursor for the biosynthesis of
aromatic amino acids,
siderophores and metabolites such as
folate,
ubiquinone and
vitamin K. The
shikimate pathway is present in bacteria, fungi, algae, plants and apicomplexan parasites, but is absent in humans. The
EPSP synthase enzyme produces 5-enolpyruvylshikimate 3-phosphate and
phosphate from
phosphoenolpyruvate and
shikimate 3-phosphate via a
transferase reaction, and is the target of the
herbicide glyphosate. The Acinetobacter baumannii gene encoding
EPSP synthase, aroA, has previously been demonstrated to be essential during host
infection for the growth and survival of this clinically important
drug-resistant ESKAPE pathogen.
Prephenate dehydrogenase is also encoded by the bifunctional A. baumannii aroA gene, but its activity is dependent upon
EPSP synthase since it operates downstream of the
shikimate pathway. As part of an effort to evaluate new antimicrobial targets, recombinant A. baumannii EPSP (AbEPSP) synthase, comprising residues Ala301-Gln756 of the aroA gene product, was overexpressed in Escherichia coli, purified and crystallized. The crystal structure, determined to 2.37 Å resolution, is described in the context of a potential antimicrobial target and in comparison to EPSP synthases that are resistant or sensitive to the
herbicide glyphosate.