On-column refolding purification of DT389-hIL13 recombinant protein expressed in Escherichia coli

Orthogonal optimization of prokaryotic expression of a natural snake venom phospholipase A2 inhibitor from Sinonatrix annularis

Phospholipase A2 (PLA2) is a calcium-dependent enzyme that is involved in inflammatory processes such as the liberation of free arachidonic acid from the membrane pool for the biosynthesis of eicosanoids. Snake venom are known containing PLA2s (svPLA2s) which exhibit a wide variety of pharmacological effects including neurotoxicity, cardiotoxicity, myotoxicity and hemorrhage. Therefore, inhibition of svPLA2 would be advantageous to successful envenomation treatment. A gamma type PLI (PLA2 inhibitor) has been extracted from the serum of Sinonatrix annularis, a non-venomous snake indigenous to China. This showed strong inhibition of Deinagkistrrodon acutus PLA2, however, the PLIγ level in the serum and snake resource are not sufficiently sustainable for further research. To overcome these limitations, we constructed a His6-PLIγ pET28 fusion expression vector and transformed Escherichia coli BL21. To improve the expression of PLIγ, an orthogonal experiment [L16(4)(5)] was performed to optimize induction parameters. The optimized condition was determined to be: induction by 0.4 mM isopropyl-β-D-thiogalactoside (IPTG) for 6 h to the recombinant BL21 after its OD600 was 0.8, with continuous shaking cultivation at 190 rpm and 35 °C. Under these conditions, the amount of expressed protein could reach 57 mg/L. The His6-PLIγ was purified by nickel affinity chromatography and renatured by On-column refolding. The resulting PLIγ showed a good inhibitory effect of enzymatic activities to venom PLA2 isolated from D. acutus. Moreover, the PLIγ had a wide anti-hemorrhage activities to D. acutus, Naja atra and Agkistrodon halys venom.

Prokaryotic expression, purification, and refolding of leukocyte cell-derived chemotaxin 2 and its effect on gene expression of head kidney-derived macrophages of a teleost fish, ayu (Plecoglossus altivelis)

Leukocyte cell-derived chemotaxin 2 (LECT2) is reported to be an immunorelevant protein in ayu (Plecoglossus altivelis). In this study, ayu LECT2 mature peptide (aLECT2m) was expressed as insoluble inclusion bodies in Escherichia coli. The denatured recombinant aLECT2m (raLECT2m) was refolded by a size-exclusion chromatography refolding process achieved by using arginine-containing mobile phase and a decreasing urea gradient. The in vitro chemotactic activity assay showed that the refolded raLECT2m had the bioactivity. By using suppression subtractive hybridization (SSH) method, we further identified up-regulated genes in ayu macrophages treated with refolded raLECT2m. These genes were tightly involved in endocytosis, hydrolysis, transcriptional regulation, signal transduction, and so on. Moreover, real-time quantitative PCR (RT-qPCR) results confirmed that selected 10 genes expression was significantly up-regulated in refolded raLECT2m-treated ayu macrophages. This study provides a basis for further studies of the mechanism of cytokine LECT2 in fish immune responses.