Cloning and expression of SmDXS2 gene in Swertia mussotii / 中国中药杂志

1-deoxy-D-xylulose-5-phosphate synthase2(DXS2) is the first key enzyme of the MEP pathway,which plays an important role in terpene biosynthesis of plants. According to the data of Swertia mussotii transcriptome, DXS2 gene(Gen Bank number MH535905) was cloned and named as Sm DXS2. The bioinformatics results showed that Sm DXS2 has no intron,with a 2 145 bp open reading frame encoding a polypeptide of 714 amino acids. They are belonging to 20 kinds of amino acids,and the most abundant amino acids include Ala,Gly and Trp. The predicted protein molecular weight was 76. 91 k Da and its theoretical isoelectric point(p I) was6. 5,which belonging to a hydrophilic protein. α-Helix and loop were the major motifs of predicted secondary structure of DXS2. The three function domains are TPP＿superfamily,Transket＿pyr＿ superfamily and Transketolase＿C superfamily,respectively. The Sm DXS2 protein shared high identity with other DXS2 proteins of plants. Phylogenetic analysis showed that Sm DXS2 protein is grouped with the gentian DXS2 protein. The recombinant protein of Sm DXS2 gene in Escherichia coli was approximately 92. 00 k Da(containing sumo-His tag protein 13 k Da),which was consistent with the anticipated size.This work will provide a foundation for further functional research of Sm DXS2 protein and increasing the product of iridoid compound by genetic engineering in S. mussotii.

Cloning and expression of geranyl pyrophosphate synthase gene in Swertia mussotii / 中草药

Objective: To clone the geranyl pyrophosphate synthase gene from Swertia mussotii (SmGPPS), analyze the bioinformation of SmGPPS, and perform the gene expression. Methods: According to the SmGPPS gene sequence of transcriptome of S. mussotii, the specific primers were designed, the cDNA complete sequences was obtained by RT-PCR and the sequence was analyzed using bioinformatics. Prokaryotic expression vector pET-28a-SmGPPS was constructed and transformed into Escherichia coli BL-21 (DE3) for expression under 37℃ and induced by 1 mmol/L IPTG. The relative expression of gene SmGPPS in the leaf, stem, and flower of S. mussotii was also studied. Results: The results showed that SmGPPS cDNA complete sequences had a length of 1 119 bp encoding 372 amino acid residues. And the protein secondary and tertiary structures were analyzed and forecasted. The SmGPPS protein shared high identity with other GPPS proteins of plants. The SDS-PAGE results showed that the expressed proteins were consistent with the anticipated size. Relative RT-PCR analysis indicated that SmGPPS showed the highest transcript abundance in the leaf. Conclusion: This work will provide a foundation for further functional research of SmGPPS protein and increasing the product of iridoid compound by genetic engineering in S. mussotii.