期刊
PHYTOCHEMISTRY
卷 145, 期 -, 页码 48-56出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.phytochem.2017.10.004
关键词
Terpenoid; Iridoid; Short chain alcohol dehydrogenase; Natural product biosynthesis
资金
- UK Biotechnological and Biological Sciences Research Council (BBSRC) [BB/L014130/1]
- Engineering and Physical Sciences Research Council (EPSRC) [BB/L014130/1]
- National Center for Biotechnology Information Sequence Read Archive under BioProject [PRJNA379302]
- US National Science Foundation Plant Genome Research Program [IOS-1444499]
- BBSRC [BB/N007905/1, BBS/E/J/000CA512, BBS/E/J/000PR9790, BB/L014130/1] Funding Source: UKRI
- Direct For Biological Sciences
- Division Of Integrative Organismal Systems [1444499] Funding Source: National Science Foundation
- Biotechnology and Biological Sciences Research Council [BB/N007905/1, BB/L014130/1, BBS/E/J/000CA512, BBS/E/J/000PR9790] Funding Source: researchfish
Nepetalactones are iridoid monoterpenes with a broad range of biological activities produced by plants in the Nepeta genus. However, none of the genes for nepetalactone biosynthesis have been discovered. Here we report the transcriptomes of two Nepeta species, each with distinctive profiles of nepetalactone stereoisomers. As a starting point for investigation of nepetalactone biosynthesis in Nepeta, these transcriptomes were used to identify candidate genes for iridoid synthase homologs, an enzyme that has been shown to form the core iridoid skeleton in several iridoid producing plant species. Iridoid synthase homologs identified from the transcriptomes were cloned, heterologously expressed, and then assayed with the 8-oxogeranial substrate. These experiments revealed that catalytically active iridoid synthase enzymes are present in Nepeta, though there are unusual mutations in key active site residues. Nevertheless, these enzymes exhibit similar catalytic activity and product profile compared to previously reported iridoid synthases from other plants. Notably, four nepetalactone stereoisomers with differing stereochemistry at the 4 alpha and 7 alpha positions - which are generated during the iridoid synthase reaction - are observed at different ratios in various Nepeta species. This work strongly suggests that the variable stereochemistry at these 4 alpha and 7 alpha positions of nepetalactone diastereomers is established further downstream in the iridoid pathway in Nepeta. Overall, this work provides a gateway into the biosynthesis of nepetalactones in Nepeta. (C) 2017 The Author(s). Published by Elsevier Ltd.
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