Cloning and expression analysis of isopentenyl pyrophosphate  isomerase gene in Gentiana rigescens

The ORF of isopentenyl pyrophosphate isomerase gene（GrIDI）was cloned from young leaves of Gentiana rigescens by RT-PCR technology according to the GrIDI sequence of transcriptome of medicinal plant G. rigescens. As a result， two sequences GrIDI1 and GrIDI2 with their GenBank accession numbers KM879183 and KM879184 were obtained. Sequence analysis showed that GrIDI1 gene had a ORF of 708 bp coding for 235 amino acids. Its relative molecular weight was 27.10 ku with the theoretical isoelectric point of 5.01. GrIDI1 was a member of IDI superfamily I and may localize in cytoplasm. GrIDI1 was a hydropholic stable protein without signal peptide and composed of mainly α-helix（45.53%）and random coils（39.57%）. The active sites， metal binding sites and domain of NUDIX hydroxylase in other IDI proteins all existed in GrIDI1. GrIDI1 protein was close to GlIDI in G. lute. The results of prokaryotic expression of GrIDI1 gene in E. coli showed that the recombinant protein was approximately 53.11 ku， which was consistent with the anticipated size. The tissue-specific expression results indicated that GrIDI1 gene primarily expressed in leaf.