Stigmatella aurantiaca Sg a15 carries genes encoding type I and type II 3-deoxy-D-arabino-heptulosonate-7-phosphate synthases: involvement of a type II synthase in aurachin biosynthesis

3-Deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthases catalyse the f irst step of the shikimate pathway. Two unrelated DAHP synthase types have been described in plants and bacteria. Two type II (arioA(A2) and aroA(A5)) and one type I DAHP synthase gene (aroA(001)) were identified from the myx obacterium Stigmatella aurantiaca Sg a15. Inactivation of uroA(A5) leads to a mutant that is impaired in the biosynthesis of aurachins, which are elec tron transport inhibitors and contain an anthranilate moiety. Feeding of an thranilic acid to the mutant culture restores production of aurachins. Inac tivation of aroA(A2) and aroA(001) does not impair production of aurachins or other known secondary metabolites of S. aurantiaca Sg a15.