TY - JOUR T1 - Uncyclized xanthommatin is a key ommochrome intermediate in invertebrate coloration JF - bioRxiv DO - 10.1101/666529 SP - 666529 AU - Florent Figon AU - Thibaut Munsch AU - Cécile Croix AU - Marie-Claude Viaud-Massuard AU - Arnaud Lanoue AU - Jérôme Casas Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/03/02/666529.abstract N2 - Ommochromes are widespread pigments that mediate multiple functions in invertebrates. The two main families of ommochromes are ommatins and ommins, which both originate from the kynurenine pathway but differ in their backbone, thereby in their coloration and function. Despite its broad significance, how the structural diversity of ommochromes arises in vivo has remained an open question since their first description. In this study, we combined organic synthesis, analytical chemistry and organelle purification to address this issue. From a set of synthesized ommatins, we derived a fragmentation pattern that helped elucidating the structure of new ommochromes. We identified uncyclized xanthommatin as the elusive biological intermediate that links the kynurenine pathway to the ommatin pathway within ommochromasomes, the ommochrome-producing organelles. Due to its unique structure, we propose that uncyclized xanthommatin functions as a key branching metabolite in the biosynthesis and structural diversification of ommatins and ommins, from insects to cephalopods.CEcollision energyCVcone voltageDADdiode-array detectorESI+positive-mode electron spray ionizationLCliquid chromatographyMeOH-HClacidified methanol with 0.5% hydrochloric acidMRMmultiple reaction monitoringMSmass spectrometryMS/MStandem mass spectrometryMWmolecular weightm/zmass-to-charge ratioNMRnuclear magnetic resonanceRTretention timeSDstandard deviationSEstandard errorSIRsingle ion recordingUVultraviolet ER -