The missing link in petrobactin biosynthesis: asbF encodes a (-)-3-dehydroshikimate dehydratase

Abstract

The siderophore petrobactin harbors unique 3,4-dihydroxybenzoyl iron-liganding groups. These moieties are known to be synthesized from shikimate pathway precursors, but no reports of the biosynthetic enzymes responsible for this conversion have been published. The gene encoding AsbF from Bacillus thuringiensis 97-27 was overexpressed in an Escherichia coli host. AsbF rapidly and efficiently transforms (-)-3-dehydroshikimate (DHS) into 3,4-dihydroxybenzoate (kcat DHS = 217 ± 10 min -1; Km DHS = 125 ± 14 μM) at 37°C and has an absolute requirement for divalent metal. Finally, the pH versus kcat DHS profile revealed two ionizable groups (pK a1 = 7.9 ± 0.1, and pKa2 = 9.3 ± 0.1). © 2008 American Chemical Society.