Abstract:
The objective of this research was to clone 1-deoxy-
D-xylulose 5-phosphate reductoisomerase gene (
MoDXR) and its promoter sequence from
Morinda officinalis and carry out bioinformatic analysis,
cis-acting elements analysis, and prokaryotic expression. On the basis of the
MoDXR gene sequence obtained from the
M. officinalis transcriptome and with NCBI-ORFfinder analysis, a pair of specific primers were designed, and used for RT-PCR amplification. The promoter region sequence at the 5' end of
MoDXR gene was isolated by the genome walking technique. Localization of
MoDXR was carried out by subcellular analysis. The prokaryotic expression plasmid pET-28a-
MoDXR was constructed and transfected into
Escherichia coli BL21(DE3) chemically-competent cells; the recombiant plasmid expressed fusion protein after the induction by IPTG. The full-length cDNA of
MoDXR was 2 015 bp, and open reading frame (ORF) size was 1 425 bp, and it encoded 474 amino acid residues and had a molecular mass of 51.27 kD. Sequence comparison with BlastP to the NCBI database revealed that
MoDXR had high sequence similarity with many other DXRs, such as
Coffea arabica DXR (
CaDXR) and
Rauvolfia verticillata DXR (
RvDXR). A phylogenetic tree revealed that
MoDXR had its closest relationship with DXR from
Coffea arabica and
Gardenia jasminoides. The subcellular localization revealed that
MoDXR protein was located on the chloroplast. Plantcare analysis indicated that the promoter region sequence of
MoDXR was 1 493 bp, covering multiple light, stress, and hormone-responsive
cis-regulatory elements; protein electrophoresis showed that the expressed protein was the anticipated size. This research lays the foundation for further purification and structural and functional characterization of the
MoDXR protein.