Phenylalanine ammonia-lyase (PAL) is the key entry enzyme of plant phenylpropanoid pathway. It plays an important role in the biosynthesis of podophyllotoxin, an anti-tumor lignan that is currently produced from its main natural source Sinopodophyllum hexandrum (Royle) Ying. In this study, we cloned the gene ShPAL encoding phenylalanine ammonia-lyase by RT-PCR from the root of S. hexandrum ecotype inhabited in the Aba' district, Sichuan, based on its public SRA transcriptome data-package. Bioinformatics analyses showed that the ShPAL-encoded protein is composed of 711 amino acids, contains the conserved domains of PAL, and has the signature motif within the active center of aromatic ammonia-lyases. Moreover, ShPAL protein was predicted to have a secondary structure mainly composed of α-helix and random coil, a typical 'seahorse' shape monomer tertiary structure, and a homologous tetramer three-dimensional structure by Swiss-Modelling. The phylogenetic lineage analysis indicated ShPAL was of the highest sequence identity and the shortest evolutionary distance with the PAL of Epimedium sagittatum from the same Berberidaceae family. Subcellular localization experiments showed that ShPAL protein was mainly distributed in the cytoplasm, despite of a minority on the endoplasmic reticulum membrane. Furthermore, ShPAL protein was recombinantly expressed in Escherichia coli and purified by histidine-tag affinity chromatography. Its enzymatic activity was determined up to 20.91 U/mg, with the optimum temperature of 41 ℃ and pH of 9.0. In contrast, the enzyme activity of its F130H mutant decreased by about 23.6%, yet with the same trends of change with temperature and pH, confirming that phenylalanine at this position does affect the substrate specificity of PAL. Both the wild type and the mutant have relatively poor thermostability, but good pH-stability. These results may help to further investigate the regulatory role of PAL in the process of podophyllotoxin biosynthesis and advance the heterologous synthesis of podophyllotoxin to protect the germplasm resource of S. hexandrum. They also demonstrate that ShPAL has a potential application in biochemical industry and biomedicine.
Phenylalanine Ammonia-Lyase/metabolism* ; Podophyllotoxin ; Phylogeny ; Cloning, Molecular

Phenylalanine ammonia-lyase (PAL), which catalyzes the conversion from L-phenylalanine to trans-cinnamic acid, is a well-known key enzyme and a connecting step between primary and secondary metabolisms in the phenylpropanoid biosynthetic pathway of plants and microbes. Schisandra chinensis, a woody vine plant belonging to the family of Magnoliaceae, is a rich source of dibenzocyclooctadiene lignans exhibiting potent activity. However, the functional role of PAL in the biosynthesis of lignan is relatively limited, compared with those in lignin and flavonoids biosynthesis. Therefore, it is essential to clone and characterize the PAL genes from this valuable medicinal plant. In this study, molecular cloning and characterization of three PAL genes (ScPAL1-3) from S. chinensis was carried out. ScPALs were cloned using RACE PCR. The sequence analysis of the three ScPALs was carried out to give basic characteristics followed by docking analysis. In order to determine their catalytic activity, recombinant protein was obtained by heterologous expression in pCold-TF vector in Escherichia coli (BL21-DE3), followed by Ni-affinity purification. The catalytic product of the purified recombinant proteins was verified using RP-HPLC through comparing with standard compounds. The optimal temperature, pH value and effects of different metal ions were determined. V_max, K_cat and K_m values were determined under the optimal conditions. The expression of three ScPALs in different tissues was also determined. Our work provided essential information for the function of ScPALs.
Cloning, Molecular ; Escherichia coli/metabolism* ; Phenylalanine/metabolism* ; Phenylalanine Ammonia-Lyase/chemistry* ; Recombinant Proteins ; Schisandra/genetics*

In order to reveal the induced resistance mechanism of tobacco treated with copper solution to potato virus Y-vein necrosis strain (PVY(N)), disease indexes, contents of virus and some physiological and biochemical indexes in tobacco were studied. The results showed that when treated at the copper concentration of 0.8 mg x L(-1), the symptom displayed and vein necrosis on tobacco were postponed, the disease index and content of virus sharply decreased , and the content of chlorophyll a, chlorophyll b and phenylalanine ammonia lyase (PAL) activity remarkably increased. Furthermore, vein necrosis closely linked to contents of total phenol and flavonoid. In this study, the contents of total phenol and flavonoid were promoted when treated with a solution at the copper concentration of 0.8 mg x L(-1). But the contents of total phenol and flavonoid reached to the first peak at the 3rd day after inoculation, and then decreased to the lowest levels which even were lower than those of the control after inoculating PVY(N). Then the contents of total phenol and flavonoid increased slowly from the 6td but still lower than those of the control. The result implied that spraying copper solution might play an important role in induced resistance of tobacco to vein necrosis disease and strengthen the antiviral capability to PVY(N).
Chlorophyll ; metabolism ; Copper ; pharmacology ; Immunity, Innate ; drug effects ; Phenylalanine Ammonia-Lyase ; metabolism ; Potyvirus ; growth & development ; Tobacco ; drug effects ; metabolism ; virology

To investigate roles of nitric oxide (NO) signal in accumulations of phenolic acids in abscisic.acid (ABA)-induced Salvia miltiorrhiza hairy roots, S. miltiorrhiza hairy roots were treated with different concentrations of sodium nitroprusside (SNP)-an exogenous NO donor, for 6 days, and contents of phenolic acids in the hairy roots are determined. Then with treatment of ABA and NO scavenger (2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1- oxyl-3-oxide, c-PTIO) or NO synthase inhibitor (NG-nitro-L-arginine methyl ester, L-NAME), contents of phenolic acids and expression levels of three key genes involved in phenolic acids biosynthesis were detected. Phenolic acids production in S. miltiorrhiza hairy roots was most significantly improved by 100 µmoL/L SNP. Contents of RA and salvianolic acid B increased by 3 and 4 folds. ABA significantly improved transcript levels of PAL (phenylalanine ammonia lyase), TAT (tyrosine aminotransferase) and RAS (rosmarinic acid synthase), and increased phenolic acids accumulations. However, with treatments of ABA+c-PTIO or ABA+L-NAME, accumulations of phenolic acids and expression levels of the three key genes were significantly inhibited. Both NO and ABA can increase accumulations of phenolic acids in S. miltiorrhiza hairy roots. NO signal probably mediates the ABA-induced phenolic acids production.
Abscisic Acid ; pharmacology ; Benzofurans ; metabolism ; Free Radical Scavengers ; pharmacology ; Hydroxybenzoates ; metabolism ; Nitric Oxide ; metabolism ; Phenylalanine Ammonia-Lyase ; metabolism ; Plant Roots ; metabolism ; Salvia miltiorrhiza ; metabolism ; Tyrosine Transaminase ; metabolism

Rosmarinic acid (RA), a phenolic acid, is one of the important secondary metabolites produced in Salvia miltiorrhiza. To observe the influence of salicylic acid (SA), an elicitor, on the synthesis of RA and related enzymes, we treated the cell suspension cultures of S. miltiorrhiza with SA and L-a-aminooxy-beta-phenylpropionic acid (AOPP), a competitive inhibitor of tyrosine aminotransferase (TAT). Under this condition, the activities of related enzymes, such as phenylalanine ammonia-lyase and TAT were traced and assayed; the accumulative amount of RA was measured. The results showed that the PAL activity reached the peak at 4 h, 124% higher than that of the control, and the content of RA reached its maximum ((5.914 +/- 0.296) mg/g dry weight) at 8 h, after treated by 6.25 mg/L SA on day 6 of the suspension culture. The results of treatment with 0.1 micromol/L AOPP showed that AOPP affected little on the TAT activity, while the PAL activity was significantly influenced, with 44% lower than that of the control at 6 h. Meanwhile, the reduced accumulation of RA ((4.709 +/- 0.204) mg/g dry weight) paralleled with the decrease in PAL activity. The co-treatment by 0.1 micromol/L AOPP and 6.25 mg/L SA relieved the restriction imposed by AOPP on PAL, and made the cell cultures accumulate more RA than sole treatment with AOPP, indicated that SA induced the accumulation of RA in suspension cell culture of S. miltiorrhiza, and the rate-limiting effect of PAL was stronger than TAT.
Cell Culture Techniques ; methods ; Cinnamates ; metabolism ; Depsides ; metabolism ; Phenylalanine Ammonia-Lyase ; metabolism ; Plant Cells ; metabolism ; Salicylic Acid ; pharmacology ; Salvia miltiorrhiza ; cytology ; growth & development ; metabolism ; Suspensions ; Tyrosine Transaminase ; metabolism

We studied the influence of the concentration of Ca2+ (0-50 mmol/L) in culture medium on the synthesis of rosmarinic acid (RA) and related enzymes in Salvia miltiorrhiza suspension cultures. Using verpamil (VP, a calcium channel antagonist) and ionophore A23187, we studied the mechanism of secondary metabolites of Salvia miltiorrhiza suspension cultures influenced by the concentration of Ca2+ in the culture medium. The synthesis of intracellular RA in 6-day incubation was significantly dependent on the medium Ca2+ concentration. At the optimal Ca2+ concentration of 10 mmol/L, a maximal RA content of 20.149 mg/g biomass dry weight was reached, which was about 37.3% and 20.4% higher than that at Ca2+ concentrations of 1 and 3 mmol/L, respectively. The variation of the activity of PAL and TAT, two key enzymes of the two branches of RA, could be affected by the concentration of Ca2+ in culture medium. The change of their activity occurred prior to the accumulation of RA, which suggested both of the key enzymes be involved in the synthesis of RA. Meanwhile, the enzymatic action of PAL was more distinct than TAT. The treatment of VP and A23187, respectively, indicated that the influence of RA affected by the concentration of Ca2+ in the culture medium was accomplished by the intracellular Ca2+, and the flow of Ca2+ from the extracellular to the intracellular environment could also participate in this process.
Calcium ; pharmacology ; Cinnamates ; metabolism ; Culture Media ; Culture Techniques ; methods ; Depsides ; metabolism ; Phenylalanine Ammonia-Lyase ; metabolism ; Salvia miltiorrhiza ; chemistry ; enzymology ; growth & development ; Tyrosine Transaminase ; metabolism

Nitric oxide has emerged as a key signaling molecule in plants recently. The role of nitric oxide in elicitor-induced defense responses of plants has been extensively investigated. In this work, sodium nitroprusside was utilized as the donor of nitric oxide to investigate the effects of exogenous nitric oxide on hypericin production and cell growth of suspension cell cultures of Hypericum perforatum L.. Compared with the untreated Hypericum perforatum L. suspension cells, external application of 0.5 and 15.0 mmol/L sodium nitroprusside induced 1.4 and 0.5-fold dry cell weight, and 0.9 and 2.1-fold hypericin content respectively. The results showed that low concentration of sodium nitroprusside promoted the growth of Hypericum perforatum L. suspension cells, while high concentration of sodium nitroprusside enhanced hypericin biosynthesis in Hypericum perforatum L. suspension cells. The maximum hypericin production was achieved by adding 0.5 mmol/L and 15.0 mmol/L sodium nitroprusside to the culture at day 0 and day 14 respectively, increasing the total hypericin yield by nearly 3.2-fold. The effects of sodium nitroprusside on hypericin content and growth of Hypericum perforatum L. suspension cells were abolished by nitric oxide specific scavenger 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, which indicated that the effects of the application of sodium nitroprusside were caused by nitric oxide released from sodium nitroprusside rather than sodium nitroprusside itself. The results also showed that 15.0 mmol/L sodium nitroprusside stimulated the activities of phenylalanine ammonia-lyase (PAL), one of the key enzymes of phenylpropanoid pathway, in suspension cells of Hypericum perforatum L., which suggested that the synthetic pathway of hypericin might be activated by NO through triggering the defense responses of Hypericum perforatum L. suspension cells.
Cells, Cultured ; Hypericum ; cytology ; drug effects ; metabolism ; Nitric Oxide ; metabolism ; Nitroprusside ; pharmacology ; Perylene ; analogs & derivatives ; metabolism ; Phenylalanine Ammonia-Lyase ; metabolism ; Plant Growth Regulators ; biosynthesis

To construct a safer and more efficient gene engineering Lactococcus Lactis for expressing phenylalaine ammonia lyase (PAL) which will be benefit for PKU therapy, pal cDNA of Parsly and synthesized sequence based on Lactococcus Lactis bias codons were recombined into two Lactococcus Lactis NICE systems. The activities of the expressed PAL were detected, and the effect of Lactococcus Lactis bias codons on the expression of exterior protein was analyzed. The results showed that the expression level of PAL was increased by using Lactococcus Lactis bias codons in both Lactococcus Lactis NICE systems. Through which several safer andmore efficient strains of the gene engineering Lactococcus Lactis were obtained.
Cloning, Molecular ; Codon ; genetics ; Genetic Vectors ; genetics ; Lactococcus lactis ; genetics ; metabolism ; Phenylalanine Ammonia-Lyase ; biosynthesis ; genetics ; Recombinant Proteins ; biosynthesis ; metabolism ; Transformation, Bacterial

OBJECTIVETo study the anabolic rule of secondary metabolites and dynamic activity of isoenzyme in Chrysanthemum morifolium originating from Wenxian county during blossoming stages.

METHODThe flavonoid, chlorogenic acid and anthocyanin content as well as the PAL, PPO and POD activity were determined in C. morifolium originating from Wenxian county during blossoming stages.

RESULT AND CONCLUSIONThe content of flavonoid and chlorogenic acid was the highest at 70% of full blossom, the anthocyanin at 50% and PPO activity at 30% with the same trend of two cultivars. Between the two cultivars, the trend of PAL and POD was different. The highest of "huaidabaiju" appeared at 70% and 30%, but that of "huaixiaobaiju" appeared at 50% and 50%.

Anthocyanins ; metabolism ; Catechol Oxidase ; metabolism ; China ; Chlorogenic Acid ; metabolism ; Chrysanthemum ; enzymology ; growth & development ; metabolism ; Flavonoids ; metabolism ; Flowers ; enzymology ; growth & development ; metabolism ; Peroxidase ; metabolism ; Phenylalanine Ammonia-Lyase ; metabolism ; Plants, Medicinal ; enzymology ; growth & development ; metabolism ; Seasons ; Species Specificity

The increasing demand of Chinese materia medica could not be supplied by wild resource, and the cultivated medicinal materials become popular, which led to decreased quality of many medicinal materials due to the difference of the circumstance between the wild and the cultivated. How to improve quality becomes key points of Chinese medicine resource. The leaves of Scutellaria baicalensis were sprayed with H₂O₂, the activities of superoxide dismutase (SOD) and catalase (CAT) changed little, but there had been a marked decrease of peroxidase (POD) and ascorbic oxidase (APX), which showed that the antioxidase system declined. Meanwhile, H₂O₂, as enhanced the expression of phenylalnine ammonialyase (PAL) and β-glucuronidase (GUS) as well as activity of PAL, promoted the biosynthesis and biotransformation of flavonoids. At the day 2 after treated, H₂O₂ of 0.004 μmol·L⁻¹ the contents of the baicalin and the wogonoside decreased slightly, but the contents of the baicalein and the wogonin increased significantly, the baicalein from 0.094% to 0.324%, the wogonin from 0.060% to 0.110%, i. e. increased 246% and 83.3%, respectively.
Ascorbate Oxidase ; metabolism ; Catalase ; metabolism ; Drugs, Chinese Herbal ; chemistry ; Flavanones ; analysis ; Flavonoids ; analysis ; Glucosides ; analysis ; Glucuronidase ; metabolism ; Hydrogen Peroxide ; Peroxidase ; metabolism ; Phenylalanine Ammonia-Lyase ; metabolism ; Scutellaria baicalensis ; metabolism ; Secondary Metabolism ; Superoxide Dismutase ; metabolism