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

Abstract.

3-Deoxy-d-arabino-heptulosonate-7-phosphate (DAHP) synthases catalyse the first step of the shikimate pathway. Two unrelated DAHP synthase types have been described in plants and bacteria. Two type II (aroA _A2 and aroA _A5) and one type I DAHP synthase gene (aroA ₀₀₁) were identified from the myxobacterium Stigmatella aurantiaca Sg a15. Inactivation of aroA _A5 leads to a mutant that is impaired in the biosynthesis of aurachins, which are electron transport inhibitors and contain an anthranilate moiety. Feeding of anthranilic acid to the mutant culture restores production of aurachins. Inactivation of aroA _A2 and aroA ₀₀₁ does not impair production of aurachins or other known secondary metabolites of S. aurantiaca Sg a15.