Cloning and analysis of STR gene and its promoter from Uncaria / 药学学报

On the basis of the Uncaria transcriptome, specific primers were designed for UrSTR. The full-length cDNA of UrSTR (GeneBank: OL310251) was 1 541 bp, encoding 345 amino acid residues, and the promoter region sequence of UrSTR (GeneBank: OL310252) was 1 179 bp. Phylogenetic tree is revealed that UrSTR had a closest relationship with STR from Ophiorrhiza pumila and Ophiorrhiza japonica. Localization of UrSTR protein is revealed located in the vacuole membrane. Plant-care analysis indicated that the promoter region sequence of UrSTR, covering multiple light, stress and hormone-response cis-regulatory elements, and verified transcriptional activity. The results of SDS-PAGE show that pET-28a-UrSTR recombinant protein was successfully expressed, and the size was anticipated. The UrSTR prokaryotic expression system needs to be optimized in the later stage. The research lays the foundation for further purification to study its structure and functional characterization of the UrSTR protein.

Strictosidine synthase, an indispensable enzyme involved in the biosynthesis of terpenoid indole and β-carboline alkaloids / 中国天然药物

Terpenoid indole (TIAs) and β-carboline alkaloids (BCAs), such as suppressant reserpine, vasodilatory yohimbine, and antimalarial quinine, are natural compounds derived from strictosidine. These compounds can exert powerful pharmacological effects but be obtained from limited source in nature. the whole biosynthetic pathway of TIAs and BCAs, The Pictet-Spengler reaction catalyzed by strictosidine synthase (STR; EC: 4.3.3.2) is the rate-limiting step. Therefore, it is necessary to investigate their biosynthesis pathways, especially the role of STR, and related findings will support the biosynthetic generation of natural and unnatural compounds. This review summarizes the latest studies concerning the function of STR in TIA and BCA biosynthesis, and illustrates the compounds derived from strictosidine. The substrate specificity of STR based on its structure is also summarized. Proteins that contain six-bladed four-stranded β-propeller folds in many organisms, other than plants, are listed. The presence of these folds may lead to similar functions among organisms. The expression of STR gene can greatly influence the production of many compounds. STR is mainly applied to product various valuable drugs in plant cell suspension culture and biosynthesis in other carriers.

Transcriptome analysis of stem wood of Nothapodytes nimmoniana (Graham) Mabb. identifies genes associated with biosynthesis of camptothecin, an anti-carcinogenic molecule.

Camptothecin (CPT), a monoterpene indole alkaloid, is a potent inhibitor of DNA topoisomerase I and has applications in treating ovarian, small lung and refractory ovarian cancers. Stem wood tissue of Nothapodytes nimmoniana (Graham) Mabb. (family Icacinaceae) is one of the richest sources of CPT. Since there is no genomic or transcriptome data available for the species, the present work sequenced and analysed transcriptome of stem wood tissue on an Illumina platform. From a total of 77,55,978 reads, 9,187 transcripts were assembled with an average length of 255 bp. Functional annotation and categorization of these assembled transcripts unraveled the transcriptome architecture and also a total of 13 genes associated with CPT biosynthetic pathway were identified in the stem wood tissue. Four genes of the pathway were cloned to full length by RACE to validate the transcriptome data. Expression analysis of 13 genes associated with CPT biosynthetic pathway in 11 different tissues vis-à-vis CPT content analysis suggested an important role of NnPG10H, NnPSLS and NnPSTR genes in the biosynthesis of CPT. These results indicated that CPT might be synthesized in the leaves and then perhaps exported to stem wood tissue for storage.