报告摘要：The loline alkaloids are a group of insecticidal alkaloids produced by endophytic fungi living inside of cool-season grasses. These small secondary metabolites consist of a pyrrolizidine ring bearing an amino group and a strained ether bridge in a very unusual context for a biological product. We have identified and sequenced the gene cluster that encodes the enzymes responsible for synthesizing the loline alkaloids, and, with a combination of various chemical and molecular biological techniques, we have established the biochemical pathway that fungi use to prepare lolines, and we have mostly identified which enzymes are responsible for catalyzing which steps in the biosynthesis. Among our more unusual findings is that a PLP-dependent gamma-lyase, LolC, probably catalyzes the formation of a C–N bond in the first committed step of loline biosynthesis, and that a single non-heme iron-dependent oxidase, LolO, is responsible for introducing both C–O bonds of the ether bridge in a four-electron oxidation.