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Proc Natl Acad Sci U S A. 2016 Nov 22;113(47):E7619-E7628. Epub 2016 Nov 7.

The biosynthetic pathway of the nonsugar, high-intensity sweetener mogroside V from Siraitia grosvenorii.

Author information

1
Institute of Plant Sciences, Agricultural Research Organization-Volcani Center, Bet Dagan 5025000, Israel.
2
Institute of Plant Sciences, Agricultural Research Organization-Newe Ya'ar Center, Ramat Yishay 3009500, Israel.
3
Consultant, Protein Modelling, Gedera 7042703, Israel.
4
Department of Biological Services, Weizmann Institute of Science, Rehovot 7610001, Israel.
5
Department of Chemistry, Bar-Ilan University, Qiryat Ono 5290000, Israel.
6
Roy J. Carver Biotechnology Center, University of Illinois, Urbana, IL 61801.
7
Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163.
8
Institute of Plant Sciences, Agricultural Research Organization-Volcani Center, Bet Dagan 5025000, Israel; vcaris@agri.gov.il.

Abstract

The consumption of sweeteners, natural as well as synthetic sugars, is implicated in an array of modern-day health problems. Therefore, natural nonsugar sweeteners are of increasing interest. We identify here the biosynthetic pathway of the sweet triterpenoid glycoside mogroside V, which has a sweetening strength of 250 times that of sucrose and is derived from mature fruit of luo-han-guo (Siraitia grosvenorii, monk fruit). A whole-genome sequencing of Siraitia, leading to a preliminary draft of the genome, was combined with an extensive transcriptomic analysis of developing fruit. A functional expression survey of nearly 200 candidate genes identified the members of the five enzyme families responsible for the synthesis of mogroside V: squalene epoxidases, triterpenoid synthases, epoxide hydrolases, cytochrome P450s, and UDP-glucosyltransferases. Protein modeling and docking studies corroborated the experimentally proven functional enzyme activities and indicated the order of the metabolic steps in the pathway. A comparison of the genomic organization and expression patterns of these Siraitia genes with the orthologs of other Cucurbitaceae implicates a strikingly coordinated expression of the pathway in the evolution of this species-specific and valuable metabolic pathway. The genomic organization of the pathway genes, syntenously preserved among the Cucurbitaceae, indicates, on the other hand, that gene clustering cannot account for this novel secondary metabolic pathway.

KEYWORDS:

functional genomics; metabolic pathway discovery; mogrosides

PMID:
27821754
PMCID:
PMC5127336
DOI:
10.1073/pnas.1604828113
[Indexed for MEDLINE]
Free PMC Article

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