Mark Bruno, Martina Vermathen, Adrian Alder, Florian Wüst, Patrick Schaub, Rob van der Steen, Peter Beyer, Sandro Ghisla and Salim Al-Babili. Insights into the formation of carlactone from in-depth analysis of the CCD8-catalyzed reactions. FEBS Press. DOI: 10.1002/1873-3468.12593
Strigolactones are a new class of phytohormones synthesized from carotenoids via carlactone. The complex structure of carlactone is not easily deducible from its precursor, a cis-configured β-carotene cleavage product, and is thus formed via a poorly understood series of reactions and molecular rearrangements, all catalyzed by only one enzyme, the carotenoid cleavage dioxygenase 8 (CCD8). Moreover, the reactions leading to carlactone are expected to form a second, yet unidentified product. In this study, we used 13C and 18O-labeling to shed light on the reactions catalyzed by CCD8. The characterization of the resulting carlactone by LC-MS and NMR, and the identification of the assumed, less accessible second product allowed us to formulate a minimal reaction mechanism for carlactone generation.