Modular metabolite assembly in C. elegans lysosome-related organelles

Signaling molecules derived from attachment of diverse primary metabolic building blocks to ascarosides play a central role in the life history of C. elegans and other nematodes; however, many aspects of their biogenesis remain unclear. Using comparative metabolomics, we show that lysosome-related organelles (LROs) are required for biosynthesis of most modular ascarosides as well as previously undescribed modular glucosides. Both modular glucosides and ascarosides are derived from highly selective assembly of moieties from nucleoside, amino acid, neurotransmitter, and lipid metabolism. We further show that cholinesterase (cest) homologs that localize to the LROs are required for assembly of both modular ascarosides and glucosides, mediating formation of ester and amide linkages between subsets of building blocks. Their specific biosynthesis suggests that modular glucosides, like ascarosides, serve dedicated signaling functions. Further exploration of LRO function and cest homologs in C. elegans and other animals may reveal additional new compound families and signaling paradigms.