In collaboration with IBS, we have biochemically characterized the bifunctional enzyme BIO3-BIO1 from Arabidopsis and solved its three-dimensional structure. Data concerning bifunctional enzyme catalyzing (or not) two successive stages of the same biosynthetic pathway are rare. This study is therefore essential from a fundamental point of view, but will also improve the production processes of molecules with high added value. This will also, in a more targeted way, enable the design of specific inhibitors aimed at therapeutic or pesticide purposes.