Polyketide synthase-derived sphingolipids determine microbiota-mediated protection against pathogens inC. elegans

Abstract

AbstractProtection against pathogens is a major function of the gut microbiota. Although bacterial natural products have emerged as crucial components of host-microbiota interactions, their exact role in microbiota-mediated protection is largely unexplored. We addressed this knowledge gap with the nematodeCaenorhabditis elegansand its microbiota isolatePseudomonas fluorescensMYb115 that is known to protect againstBacillus thuringiensis(Bt) infection. We find that MYb115-mediated protection depends on sphingolipids that are derived from an iterative type I polyketide synthase (PKS), thereby describing a noncanonical pathway of bacterial sphingolipid production. We provide evidence that MYb115-derived sphingolipids affectC. eleganstolerance to Bt infection by altering host sphingolipid metabolism. This work establishes sphingolipids as structural outputs of bacterial PKS and highlights the role of microbiota-derived sphingolipids in host protection against pathogens.