Abstract
Lolines are potent insecticidal agents produced by endophytic fungi of cool-season grasses. These alkaloids are composed of a pyrrolizidine ring system and an uncommon ether bridge linking carbons 2 and 7. Previous results indicated that 1-aminopyrrolizidine was a pathway intermediate. We used RNA interference to knock down expression of lolO, resulting in the accumulation of an alkaloid identified as exo-1-acetamidopyrrolizidine based on high-resolution MS and NMR. Genomes of endophytes differing in alkaloid profiles were sequenced, revealing that those with mutated lolO accumulated exo-1-acetamidopyrrolizidine but no lolines. Heterologous expression of wild-type lolO complemented a lolO mutant, resulting in the production of N-acetylnorloline. These results indicated that the non-heme iron oxygenase, LolO, is required for ether bridge formation, probably through oxidation of exo-1-acetamidopyrrolizidine.
Document Type
Article
Publication Date
2-2014
Digital Object Identifier (DOI)
http://dx.doi.org/10.1016/j.phytochem.2013.11.015
Funding Information
This research was supported by USDA-CSREES Grants 2009-11131030 and 2012-6701319384, National Science Foundation Grants EF-0523661 and EPS-0814194, and NIH-NIGMS Grant R01GM086888, and by The Samuel Roberts Noble Foundation, Ardmore, Oklahoma.
Repository Citation
Pan, Juan; Bhardwaj, Minakshi; Faulkner, Jerome Ralph; Nagabhyru, Padmaja; Charlton, Nikki D.; Higashi, Richard M.; Miller, Anne-Frances; Young, Carolyn A; Grossman, Robert B.; and Schardl, Christopher L., "Ether Bridge Formation in Loline Alkaloid Biosynthesis" (2014). Toxicology and Cancer Biology Faculty Publications. 43.
https://uknowledge.uky.edu/toxicology_facpub/43
Notes/Citation Information
Published in Phytochemistry, v. 98, p. 60-68.
Copyright © 2013 Elsevier Ltd. All rights reserved.
This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/