The effect of elicitors on oleanolic acid accumulation and expression of triterpenoid synthesis genes in Gentiana straminea

Gentiana straminea is native to the Qinghai-Tibet plateau, where it is exposed to extremes of cold and strong UV-B radiation. Here we showed that low temperature, but not UV-B radiation, affected the accumulation of the triterpenoid oleanolic acid. Neither of these stresses altered the expression of known triterpenoid synthesis genes. However, the application of methyl jasmonate (MeJA), but not salicylic acid (SA), significantly enhanced the accumulation of oleanolic acid, and up-regulated the triterpenoid synthesis genes, especially the expression of βAS, the gene encoding β-amyrin.     

Study of molecular mechanism of Prostaglandin E1 in inhibiting coronary heart disease

Prostaglandin E1 has been used clinically for improving heart diseases. In this study, we examined the effect of Prostaglandin E1 on blood lipid levels, heart protein and genes expression in coronary heart disease (CHD) rats. Female rats were fed either a control diet or hypercholesterolemic diet for 14 weeks. The feeding of a hypercholesterolemic diet (HCD) increased the serum TC, TG, and LDL-c levels, decreased the serum HDL-c, E2, P, FSH, LH and PRL levels in CHD rats. In addition, The feeding of a HCD diet markedly increased the content of serum TXA2, TXB2, and decreased the content of serum PGI2, and PGI2/TXA2, 6-Keto PGF1a. Furthermore, the feeding of a hypercholesterolemic diet markedly increased expression levels of myocardium Fas and Caspase-3 protein and mRNA levels, vascular endothelial growth factor and basic fibroblast growth factor mRNA, and decreased RyR2 mRNA in CHD rats. The feeding of Prostaglandin E1 for 14 weeks significantly reversed these abnormal biochemical indexes in rats. These findings suggest that Prostaglandin E1 play a obvious heart protective effect. The mechanisms may be related to restraining the excessive activation of Fas and Caspase-3 protein and modulating some gene expressions associated with CHD.     

Tuning the substrate selectivity of meta-cleavage product hydrolase by domain swapping

meta-Cleavage product (MCP) hydrolases can catalyze relatively low reactive carbon–carbon bond hydrolysis of products, which are derived from the meta-cleavage of catechols. The strict substrate selectivity of MCP hydrolases attracts an interest to understand the determinants of substrate specificity. Compared with conventional site-directed mutagenesis, domain swapping is an effective strategy to explore substrate specificity due to the large-scale reorganization of three-dimensional structure. In the present study, the hybrid MCP hydrolases BphD_LidA and MfphA_LidD were constructed by exchanging the lid domain of two parental enzymes MfphA and BphD. The residues Gly130/Ala196 (MfphA) and Gly136/Ala211 (BphD) were selected as crossover points according to structural disruption score analysis and molecular dynamics simulations. It was shown that the hybrid enzymes exhibited similar substrate selectivity with the parent enzyme providing the lid domain. Docking studies suggested that the lid domain may play a key role in determining substrate specificity by reshaping the active pocket and modulating the orientation of the substrate.     

Proteomic Analysis of Differential Proteins Related to Anti-nociceptive Effect of Electroacupuncture in the Hypothalamus Following Neuropathic Pain in Rats

Increasing evidence has been accumulated for the effectiveness of acupuncture therapy in relieving pain. However, there are limited data on regulation of protein expression after electroacupuncture (EA) intervention. Thus, the present study is designed to determine changes in protein expression following EA stimulation in rats with sciatic nerve chronic constrictive injury (CCI) induced neuropathic pain. Sixty Wistar rats were equally randomized into normal control group, CCI group, and CCI with EA stimulation (EA) group. The CCI model was established by ligature of the left sciatic nerve. EA stimulation was applied at Zusanli (ST36) and Yanglingquan (GB34) in the EA group. Differentially expressed hypothalamic proteins in the three groups were identified by 2-D gel electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry. The functional clustering and pathway of the identified proteins were analyzed by Mascot software. Results showed that, after CCI, the thermal pain threshold of the affected hind footpad was decreased and was reversed gradually by 12 sessions of EA treatment. Following EA intervention, there were 17 hypothalamic proteins identified with significant changes in the expression (>twofold). Three gene-ontologies (oxidoreductase activity, oxidation reduction, and protein binding) were enriched, while there was a significant regulation of glycolysis/gluconeogenesis/hexose metabolism pathway. These data demonstrate that EA intervention can attenuate pain via regulation of expression of multiple proteins in the hypothalamus. Further, hypothalamic glucose metabolism may be important in supporting energy and neurotransmitter homeostasis in the effects of EA intervention.     

Insights into the drug resistance induced by the BaDHPS mutations: molecular dynamic simulations and MM/GBSA studies

Dihydropteroate synthase (DHPS) is essential for the folic acid biosynthetic pathway in prokaryotes; the mutation forms for DHPS are found to be relative to the urgent drug resistance problems. In our study, the Bacillus anthracis DHPS (BaDHPS) was selected for molecular dynamics and binding free energy studies to investigate the biochemistry behaviors of the wild-type and mutation form BaDHPS proteins (D184N and K220Q). It is found that the conformational change of the ligand dihydropteroate sulfathiazole binding site in mutation D184N and K220Q systems is mainly attributed from the Loop 1, Loop 2, and Loop 7 regions, and the binding free energy of these mutation systems is lower than that of the wild-type system. Additionally, some important hydrogen bonds of the mutation systems are disrupted during the simulations. But the shortening of the distance between residue Thr67 and the ligand would cause significant change of the binding pose in the K220Q system. These studies of DHPS family will be helpful for further drug resistance investigations.

An animated Interactive 3D Complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:24