Cloning of Chalcone Isomerase Gene and Bioinformation Analysis of Erigeron breviscapus (vant) Hand Mazz.

Chalcone isomerase is a key enzyme in flavone biosynthesis regulation of Erigeron breviscapus(vant) Hand Mazz.Isolation and cloning of functional genes concerning flavone biosynthesis is crucial for using gene transfer to regulate flavone metabolism in Erigeron bre-viscapus.In this paper,the chalcone isomerase gene(CHI) was cloned from Erigeron bre-viscapus via RT-PCR and RACE(rapid amplification of cDNA ends).The full-length cDNA of chalcone isomerase gene is 996 bp(GenBank Accession No.GU208823),containing a 594 bp open reading frame(ORF),encoding a 197 amino acid protein,and having a polyadenylation signal in its 3’ untranslated region.The deduced protein molecular weight of CHI was 21.6 kD and its theoretical isoelectric point was 4.78.The CHI protein did not have trans-membrane domain and was hydrophilic.Its secondary structures were predominantly constructed by α-helic and random coils were the main component.The 3D model structure of the deduced Erigeron breviscapus protein was constructed similar to the CHI protein structure from Medicago sativa.According to variation characteristics in the N-end of CHI,we supposed that the special synthesis of breviscapine(scutellarin-7-O-glucuronide and apigenin-7-O-glucuronide) in Erigeron bre-viscapus may be concerned with the position of CHI in cell sub-structure and the assembled manner of enzymes in flavone biosynthesis.This research established the foundation for di-rectional change in flavone biosynthsis in Erigeron breviscapus(vant) Hand Mazz.