AUTHOR=Zheng Wei , Zhou Tao , Li Jun , Jiang Weike , Zhang Jinqiang , Xiao Chenghong , Wei Dequn , Yang Changgui , Xu Rong , Gong Anhui , Zhang Chen , Bi Yan 

TITLE=The Biosynthesis of Heterophyllin B in Pseudostellaria heterophylla From prePhHB-Encoded Precursor

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01259

DOI=10.3389/fpls.2019.01259

ISSN=1664-462X

ABSTRACT=<p>Plant cyclic peptides (CPs) are a large group of small molecule metabolites found in a wide variety of plants, including traditional Chinese medicinal plants. However, the majority of plant CPs have not been studied for their biosynthetic mechanisms, including heterophyllin B (HB), which is one of the characteristic chemical components of <italic>Pseudostellaria heterophylla</italic>. Here, we screened the precursor gene (<italic>prePhHB</italic>) of HB in <italic>P. heterophylla</italic> and functionally identified its correctness <italic>in vivo</italic> and <italic>in vitro</italic>. First, we developed a new method to screen the precursors of HB from 16 candidate linear peptides. According to transcriptome sequencing data, we cloned the genes that encoded the HB precursor peptides and confirmed that the <italic>prePhHB</italic>-encoded precursor peptide could enzymatically synthesize HB. Next, we generated the transgenic tobacco that expressed <italic>prePhHB</italic>, and the results showed that HB was detected in transgenic tobacco. Moreover, we revealed that <italic>prePhHB</italic> gene expression is positively correlated with HB accumulation in <italic>P. heterophylla</italic>. Mutations in the <italic>prePhHB</italic> gene may influence the accumulation of HB in <italic>P. heterophylla</italic>. These results suggest that HB is ribosomally synthesized and posttranslationally modified peptide (RiPP) derived from the precursor gene <italic>prePhHB</italic>-encoded precursor peptide, and the core peptide sequence of HB is IFGGLPPP in <italic>P. heterophylla</italic>. This study developed a new idea for the rapid identification of <italic>Caryophyllaceae</italic>-type CP precursor peptides <italic>via</italic> RNA-sequencing data mining.</p>