Biosynthesis of the antibiotic echinosporin by a novel branch of the shikimate pathway

Abstract

Echinosporin (1), a known antibiotic with a unique tricyclic acetal-lactone structure, is produced by Streptomyces erythraeus (strain Tu 4015), together with the novel 7-deoxy-echinosporin (2) as minor compound, which was fully characterized. The biosynthesis of I was established by feeding experiments with C-13-labelled precursors. The results revealed that I was formed by the shikimate pathway, with chorismate as a biosynthetic intermediate. The proposed mechanism for the conversion of chorismate into I represents a new branch of the shikimate pathway, producing a nonaromatic metabolite. In addition, the influence of aromatic amino acids and of glyphosate, an inhibitor in the shikimate pathway of plants, was investigated. (C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.