OBJECTIVETo clone the cDNA sequence of squalene synthase gene from Paris polyphylla, and characterize the biological features of the obtained SQS.

METHODUsing homology cloning and RACE technique, a full-length cDNA sequence of PpSQS gene was isolated from P. polyphylla. The obtained sequence was analyzed by bioinformatics softwares. A plasmid [named pET-30b (+)-PpSQS] was constructed for prokaryotic expression the recombinant PpSQS.

RESULTThe full-length cDNA of PpSQS gene is 1 498 bp, which contains a 1 212 bp ORF. Sequence analysis indicated that PpSQS encoded 403 amino acids residues with a calculated molecular weight (MW) of 46.36 kDa and an isoelectric point (pI) of 6.83. SDS-PAGE results showed that the recombinant PpSQS was expressed in Escherichia coli BL21 (DE3) by inducing with 1 mmol x L(-1) IPTG.

CONCLUSIONThe full-length cDNA sequence of PpSQS gene was obtained from P. polyphylla, and its molecular features were consisted with classic SQS in plant. The recombinant PpSQS was successfully expressed in E. coli.

Cloning, Molecular ; Escherichia coli ; genetics ; Farnesyl-Diphosphate Farnesyltransferase ; genetics ; Liliaceae ; enzymology ; Phylogeny ; Recombinant Proteins ; biosynthesis

In order to understand the structural characteristics of squalene synthase genes in the triterpenoids biosynthesis pathway of Crataegus pinnatifida, the squalene synthase genes of C. pinnatifida was cloned and analyzed by bioinformatics and prokaryotic expression. Two squalene synthase genes CpSQS1 and CpSQS2 were cloned from C. pinnatifida fruit by RT-PCR. The ORF length of CpSQS1 and CpSQS2 were 1 239 bp and 1 233 bp respectively, encoding 412 aa and 410 aa respectively. CpSQS1 and CpSQS2 were predicted to be stable acidic proteins by online tools. The secondary structure was mainly composed of α-helix structure, and the tertiary structure was predicted by homology modeling. Structural functional domain analysis showed that 35-367 aa of CpSQS1 and CpSQS2 cDNA containing conserved trans-isoprenyl pyrophosphate synthase domains. Transmembrane domain analysis predicted that two transmembrane domains were founded in CpSQS1 and CpSQS2. The squalene synthase amino sequence of C. pinnatifida had higher homology with the known SQS of Salvia miltiorrhiza and Glycyrrhiza glabra. Phylogenetic tree analysis showed that CpSQS1 and CpSQS2 were clustered into one branch of MdSQS1 and MdSQS2, which were consistent with the phylogenetic rule. Prokaryotic expression vector pGEX-4 T-1-CpSQS1 and pGEX-4 T-1-CpSQS2 were transformed into Escherichia coli Transetta(DE3) for induction, and the target protein was successfully expressed at 65 kDa. The expression levels of CpSQS2 were significantly higher than that of CpSQS1 in three different developmental stages of C. pinnatifida. In this study, the full-length cDNA sequences of C. pinnatifida SQS1 and SQS2 were cloned and analyzed for the first time, which provided the foundation for further study on the metabolic pathway of C. pinnatifida triterpenoids.
Amino Acid Sequence ; Cloning, Molecular ; Crataegus/genetics* ; Farnesyl-Diphosphate Farnesyltransferase/genetics* ; Fruit/enzymology* ; Phylogeny ; Plant Proteins/genetics*

This study is to reveal the correlation between CNVs of HMGR, SQS1, beta-AS gene and genuineness of liquorice. Real-time PCR was used to detect the copy number of HMGR, SQS1, beta-AS gene of liquorice. According to the results, the range of the copy number variation of HMGR gene was between 1 and 3, the copy number of SQS1 gene was 1 or 2, and the copy number of beta-AS gene was only 1. On the basis of the copy number of HMGR, SQS1 and beta-AS gene, there were five groups, type A (2 + 1 + 1), type B (1 + 1 + 1), type C (3 + 2 + 1), type D (2 + 2 + 1) and type E (3 + 1 + 1). There were two types, type A and type B, in Hangjinqi of Inner Mongolia, and the ratio of A to B was 1:1.3. There were also two types, type A and type B, in Chifeng of Inner Mongolia, and the ratio of A to B was 3:1. There were four types, type A, type B, type C and type D, in Yanchi of Ningxia province, and the ratio of A to B was 1:5.1. There were three types, type A, type B and type E, in Minqin of Gansu province, and the ratio of A to B was 2:1. So CNVs mainly existed in the liquorice from Ningxia and Gansu provinces. While the genetic background of liquorice from Hangjinqi of Inner Mongolia was stabilized. The results of the experiment proved that the correlation between CNVs and origins was one of the reasons of genuineness of liquorice.
China ; DNA Copy Number Variations ; DNA, Plant ; genetics ; Farnesyl-Diphosphate Farnesyltransferase ; genetics ; Glycyrrhiza uralensis ; enzymology ; genetics ; Hydroxymethylglutaryl CoA Reductases ; genetics ; Intramolecular Transferases ; genetics ; Real-Time Polymerase Chain Reaction

Glycyrrhiza uralensis Fisch. ex DC is widely used in traditional Chinese medicine (TCM). Among its various active components, glycyrrhizic acid is believed to be the marker component. Squalene synthase (SQS) and beta-amyrin synthase (beta-AS) are key enzymes in the biosynthetic pathway of glycyrrhizic acid in G uralensis. To reveal the effects of co-expression of SQS1 and beta-AS genes on this pathway, 7 yeast expression vectors harboring different SQS1 variants and beta-AS were constructed and expressed in Saccharomyces cerevisiae as fusion proteins. TLC and GC-MS results showed that co-expression of SQS1 and beta-AS enhanced the accumulation of beta-amyrin. The effects of SQS12 were more obvious than the other two SQS1 variants. This study is significant for further investigations concerned with exploring the biosynthesis of glycyrrhizic acid in vitro and strengthening the efficacy of G. uralensis by means of increasing the content of glycyrrhizic acid.
Farnesyl-Diphosphate Farnesyltransferase ; genetics ; metabolism ; Glycyrrhiza uralensis ; genetics ; Intramolecular Transferases ; metabolism ; Oleanolic Acid ; analogs & derivatives ; metabolism ; Plant Proteins ; genetics ; Recombinant Proteins ; metabolism ; Saccharomyces cerevisiae ; metabolism

According to the designed specific primers of gene fragment based on the Salvia miltiorrhiza transcriptome data, a full-length cDNA sequence of SQS2 from S. miltiorrhiza f. alba was cloned by the method of reverse transcription polymerase chain reaction (RT-PCR). The SmSQS2 cDNA sequence was obtained, this sequence is named SmSQS2 and its GenBank registration number is KM244731. The full length of SmSQS2 cDNA was 1245 bp, encoding 414 amino acids including 5'UTR 115 bp and 3'UTR 237 bp. Sequence alignment and phylogenetic analysis demonstrated that SmSQS2 had relative close relationship to the SQS2 of S. miltiorrhiza. The induction of E. coli [pET28-SQS2] in different temperature, induction time, IPTG concentrations and density of inducing host bacterium (A600) were performed, Shaking the culture at 30 degrees C until the A600 is approximately 0.6 and add IPTG to final concentration of 0.2 mmol x L(-1), and then the optimal expression of SmSQS2 recombinant protein were accumulated after the induction time of 20 h. The research provided important base for the study of sterol and terpene biosynthesis of SQS2 in S. miltiorrhiza f. alba.
Cloning, Molecular ; Farnesyl-Diphosphate Farnesyltransferase ; chemistry ; genetics ; metabolism ; Models, Molecular ; Molecular Sequence Data ; Phylogeny ; Plant Proteins ; chemistry ; genetics ; metabolism ; Salvia miltiorrhiza ; chemistry ; classification ; enzymology ; genetics ; Sequence Alignment

A squalene synthase gene cloned (GuSQS1, accession number in GenBank database: AM182329) from Glycyrrhiza uralensis was transferred into G. uralensis via Agrobacterium rhizogenes A4 for investigating biosynthesis pathway and enhancing synthesis of glycyrrhizic acid (GA). Hypocotyl explants from G. uralensis were infected with A. rhizogenes A4 containing GuSQS1 gene to induce the hairy roots. The hairy root lines established were selected in medium containing 0.8 mg x L(-1) phosphinothricin (PPT) and analyzed by PCR and southern blotting. The transgenic hairy roots were cultured in liquid MS medium. GA contents in transgenic hairy roots were detected by HPLC. Results showed that maximal GA content in transgenic hairy root lines was 3.6 times as high as in wild type hairy roots.
Cells, Cultured ; Farnesyl-Diphosphate Farnesyltransferase ; genetics ; metabolism ; Glycyrrhiza uralensis ; enzymology ; genetics ; growth & development ; metabolism ; Glycyrrhizic Acid ; metabolism ; Molecular Sequence Data ; Plant Proteins ; genetics ; metabolism ; Plant Roots ; enzymology ; genetics ; growth & development ; metabolism ; Plants, Genetically Modified ; enzymology ; genetics ; growth & development ; metabolism

The present study was designed to determine the effects of copy number variations (CNVs) of squalene synthase 1(SQS1) gene on the mevalonate (MVA) pathway. SQS1 gene from G. uralensis (GuSQS1) was cloned and over-expressed in Pichia pastoris GS115. Six recombinant P. pastoris strains containing different copy number of GuSQS1 were constructed. HPLC was used to assay the level of ergosterol in all transgenic P. pastoris strains containing GuSQS1. HPLC analysis showed that the contents of ergosterol in all of the transgenic P. pastoris containing GuSQS1 were higher than that in the negative control. And with the increase of copy number of GuSQS1, the content of ergosterol showed an increasing-decreasing-increasing pattern. The contents of ergosterol in 10-copy-GuSQS1 P. pastoris and 47-copy-GuSQS1 P. pastoris were significantly higher than that in the rest recombinant P. pastoris strains. In conclusion, the CNVs of GuSQS1 influence the content of secondary metabolites in the MVA pathway. The present study provides a basis for over-expressing GuSQS1 and increasing the content of glycyrrhizin in G. uralensis cultivars.
Amino Acid Sequence ; genetics ; Chromatography, High Pressure Liquid ; DNA Copy Number Variations ; genetics ; Ergosterol ; biosynthesis ; Farnesyl-Diphosphate Farnesyltransferase ; genetics ; Glycyrrhiza uralensis ; genetics ; Mevalonic Acid ; metabolism ; Pichia ; metabolism ; Plasmids ; genetics ; Real-Time Polymerase Chain Reaction ; Recombinant Proteins ; metabolism

OBJECTIVETo establish a stabilized and reliable detection system of CNVs of HMGR, SQS1, beta-AS gene of Glycyrrhiza uralensis.

METHODReal time PCR was used to detect the CNVs of HMGR, SQS1, beta-AS gene of G. uralensis.

RESULTIn the quantitative detection experiments of HMGR, SQS1, beta-AS gene of G. uralensis, the change of value of C(t) was 25.82-25.88, 29.01-29. 08, 15.52-15.56, 19.06-19.08 respectively, the alue of SD was 0.033, 0.032, 0.024, 0.011 respectively, and the value of CV was 0.12%, 0.22%, 0.16%, 0.06% respectively.

CONCLUSIONThe repeatability of detection system of Real time PCR was stabilized and reliable, and the method could be used to detect the CNVs of HMGR, SQS1, beta-AS gene of G. uralensis.

DNA Copy Number Variations ; DNA, Plant ; Farnesyl-Diphosphate Farnesyltransferase ; genetics ; Glycyrrhiza uralensis ; enzymology ; genetics ; Hydroxymethylglutaryl CoA Reductases ; genetics ; Molecular Typing ; methods ; Real-Time Polymerase Chain Reaction ; Sequence Analysis, DNA

OBJECTIVETo analyze the effect of endophytic fungi on expression amount of key enzyme genes SS (squalene synthase gene), SE (squalene epoxidase gene) and bAS (beta-amyrin synthase gene) in saponin biosynthesis and saponins content in Eleutherococcus senticosus.

METHODWound method was used for back meeting the endophytic fungi to E. senticosus. With GAPDH as internal control gene, the expression of key enzyme genes was detected by real time PCR method. E. senticosus saponins content was measured by spectrophotometry method.

RESULTWhen wound method back meeting P116-1a and P116-1b after 30 d, the expression content of SS improved significantly (P < 0.05), however the back meeting of P109-4 and P312-1 didnt change the expression of SS. After that SS expression showed reduction-equality-reduction varying trend. Thirty days after back meeting P312-1, the expression content of SE improved significantly (P < 0.05). Ninty days after back meeting P116-1b and P312-1, the expression content of SE improved significantly to 130%,161%, respectively (P < 0.05). After 120 d, back meeting four endophytic fungi, the expression of SE were significantly higher than the control (P < 0.05). Back meeting four endophytic fungi form 60 d to 120 d, the expression of bAS was significantly higher than the control (P < 0.05). The back meeting four endophytic fungi improved E. senticosus saponins content significantly (P < 0.05).

CONCLUSIONEndophytic fungi P116-1a, P116-1b, P1094 and P312-1 significantly effected the expression of key enzyme genes SS, SE and bAS and then affected E. senticosus saponins content. Among the genes, bAS was key target gene.

Eleutherococcus ; chemistry ; metabolism ; microbiology ; Endophytes ; physiology ; Farnesyl-Diphosphate Farnesyltransferase ; genetics ; Fungi ; physiology ; Gene Expression Regulation, Enzymologic ; Gene Expression Regulation, Plant ; Intramolecular Transferases ; genetics ; Saponins ; analysis ; biosynthesis ; Squalene Monooxygenase ; genetics

OBJECTIVETo analyse the polymorphism of squalene synthase gene and reveal the influence of squalene synthase (SQS) gene polymorphism on the catalytic efficiency of its encode enzyme in Glycyrrhiza uralensi.

METHODThe total RNA was extracted. PCR was used to amplify the coding sequences of squalene synthase gene, which were sequenced and analysed. The expression vectors containing different SQS gene sequences, including SQS1C, SQS1F, SQS2A, SQS2B, were constructed and transformed into Escherichia coli BL21. The fusion protein was induced to express by IPTG, then was isolated, purified and used to carry out the enzymatic reaction in vitro. GC-MS was used to analyse the production.

RESULTThere were three kinds of gene polymorphism existing in SQS1 gene of G. uralensis, including single nucleotide polymorphism (SNPs), insertion/deletion length polymorphism (InDels) and level of amino acid, the proportion of conservative replace of SQS1 was 53.94%, and there were 2 mutational sites in structural domains. The proportion of conservative replace of SQS2 was 60%, and there was 1 mutational site in structural domains. The production squalene could be detected by GC-MS in all the 4 kinds of enzymatic reactions. The capacity of accumulating squalene of SQS1F was higher than other SQS genes.

CONCLUSIONThe polymorphism of SQS gene was quite abundant in G. uralensis, which maybe the molecular foundation of the formation of high-quality liquorice.

Amino Acid Substitution ; Biocatalysis ; Cloning, Molecular ; DNA, Complementary ; chemistry ; genetics ; Electrophoresis, Polyacrylamide Gel ; Escherichia coli ; genetics ; Farnesyl-Diphosphate Farnesyltransferase ; genetics ; metabolism ; Gas Chromatography-Mass Spectrometry ; Glycyrrhiza uralensis ; enzymology ; genetics ; INDEL Mutation ; Isoenzymes ; genetics ; metabolism ; Molecular Sequence Data ; Plant Proteins ; genetics ; metabolism ; Polymorphism, Genetic ; Polymorphism, Single Nucleotide ; Recombinant Proteins ; metabolism ; Sequence Analysis, DNA ; Squalene ; metabolism