RESUMO
An open reading frame (ORF) of isopentenyl-diphosphate delta isomerase gene (FuIPI) was cloned from Fritillaria unibracteata Hsiao et K. C. Hsia. (F. unibracteata). Furthermore, the bioinformatics and functional analyses of FuIPI were performed in this study. The result showed that, the ORF of FuIPI gene was 825 bp, encoding a polypeptide of 274 amino acids in length, with a relative molecular mass of about 31 kD and a theoretical isoelectric point of 5.61. Sequence analysis showed that FuIPI contained conserved structural domains and key residues involved in the catalyzing process. The phylogenetic analysis exhibited that FuIPI was closely related to IPIs of Dendrobium officinale and Musa acuminate. Real-time PCR analysis showed that FuIPI was distributed in different tissues of F. unibracteata, but had the highest transcriptional level in leaves, followed by stems, bulbs, and flowers. Furthermore, the FuIPI protein was successfully expressed in Escherichia coli BL21(DE3). The purified FuIPI protein successfully catalyzed the conversion from isopentenyl diphosphate (IPP) to dimethylallyl pyrophosphate (DMAPP). The above results provided a theoretical basis for further investigation of the molecular role of FuIPI in the biosynthesis of alkaloids.