Insight into neofunctionalization of 2,3-oxidosqualene cyclases in B,C-ring-opened triterpene biosynthesis in quinoa

Zhou, Qian1; Sun, Peng1; Xiong, Hao-Ming2; Xie, Jiali1; Zhu, Guo-Yuan2; Tantillo, Dean J.3; Huang, Ancheng C.1

2023-10-01

10.1111/nph.19345

NEW PHYTOLOGIST   Impact Factor & Quartile

0028-646X

1469-8137

Bioactive triterpenes feature complex fused-ring structures, primarily shaped by the first-committed enzyme, 2,3-oxidosqualene cyclases (OSCs) in plant triterpene biosynthesis. Triterpenes with B,C-ring-opened skeletons are extremely rare with unknown formation mechanisms, harbouring unchartered chemistry and biology.Here, through mining the genome of Chenopodium quinoa followed by functional characterization, we identified a stress-responsive and neofunctionalized OSC capable of generating B,C-ring-opened triterpenes, including camelliol A and B and the novel (-)-quinoxide A as wax components of the specialized epidermal bladder cells, namely the quinoxide synthase (CqQS).Protein structure analysis followed by site-directed mutagenesis identified key variable amino acid sites underlying functional interconversion between pentacyclic beta-amyrin synthase (CqbAS1) and B,C-ring-opened triterpene synthase CqQS. Mutation of one key residue (N612K) in even evolutionarily distant Arabidopsis beta-amyrin synthase could generate quinoxides, indicating a conserved mechanism for B,C-ring-opened triterpene formation in plants. Quantum computation combined with docking experiments further suggests that conformations of conserved W613 and F413 of CqQS might be key to selectively stabilizing intermediate carbocations towards B,C-ring-opened triterpene formation.Our findings shed light on quinoa triterpene skeletal diversity and mechanisms underlying B,C-ring-opened triterpene biosynthesis, opening avenues towards accessing their chemistry and biology and paving the way for quinoa trait engineering and quality improvement.

2,3-oxidosqualene cyclase (OSC) B,C-ring-opened triterpenes biosynthesis Chenopodium quinoa epidermal bladder cells (EBCs) neofunctionalization stress response

SCI

English

First ; Corresponding

This work is supported by the National Natural Science Foundation of China (grant no. 32370298), the open project of BGI-Shenzhen (BGIRSZ20210014), Guangdong Basic and Applied Basic Research Foundation (2023A1515012550), the Key Laboratory of Molecular Des["32370298","BGIRSZ20210014"] ; National Natural Science Foundation of China[2023A1515012550] ; Guangdong Basic and Applied Basic Research Foundation[2019KSYS006]

Plant Sciences

Plant Sciences

WOS:001093215100001

WILEY

PLANT & ANIMAL SCIENCE

Web of Science

1.Southern Univ Sci & Technol, Key Lab Mol Design Plant Cell Factory Guangdong Hi, SUSTech PKU Inst Plant & Food Sci, Sch Life Sci,Dept Biol, Shenzhen 518055, Guangdong, Peoples R China
2.Macau Univ Sci & Technol, Macau Inst Appl Res Med & Hlth, State Key Lab Qual Res Chinese Med, Guangdong Hong Kong Macao Joint Lab Resp Infect Di, Hong Kong 999078, Guangdong, Peoples R China
3.Univ Calif Davis, Dept Chem, Davis, CA 95616 USA

Zhou, Qian,Sun, Peng,Xiong, Hao-Ming,et al. Insight into neofunctionalization of 2,3-oxidosqualene cyclases in B,C-ring-opened triterpene biosynthesis in quinoa[J]. NEW PHYTOLOGIST,2023.

Zhou, Qian.,Sun, Peng.,Xiong, Hao-Ming.,Xie, Jiali.,Zhu, Guo-Yuan.,...&Huang, Ancheng C..(2023).Insight into neofunctionalization of 2,3-oxidosqualene cyclases in B,C-ring-opened triterpene biosynthesis in quinoa.NEW PHYTOLOGIST.

Zhou, Qian,et al."Insight into neofunctionalization of 2,3-oxidosqualene cyclases in B,C-ring-opened triterpene biosynthesis in quinoa".NEW PHYTOLOGIST (2023).