Purification and characterization of recombinant human interleukin-29 expressed in Escherichia coli

Enhanced soluble expression of active recombinant human interleukin-29 using champion pET SUMO system

Current research focuses on the soluble and high-level expression of biologically active recombinant human IL-29 protein in Escherichia coli. The codon-optimized IL-29 gene was cloned into the Champion™ pET SUMO expression system downstream of the SUMO tag under the influence of the T7 lac promoter. The expression of SUMO-fused IL-29 protein was compared in E. coli Rosetta 2(DE3), Rosetta 2(DE3) pLysS, and Rosetta-gami 2(DE3). The release of the SUMO fusion partner resulted in approximately 98 mg of native rhIL-29 protein with a purity of 99% from 1 l of fermentation culture. Purified rhIL-29 was found to be biologically active, as evaluated by its anti-proliferation assay. It was found that Champion™ pET SUMO expression system can be used to obtained high yield of biologically active soluble recombinant human protein compared to other expression vector.

Cloning and expression of an anti-cancerous cytokine: human IL-29 gene in Chlamydomonas reinhardtii

Green algae, Chlamydomonas reinhardtii, with low cultivation cost, absence of endotoxins and insusceptibility to human pathogens is emerging as a potential system for the future production of recombinant proteins. The recent development of molecular tools enabling recombinant protein expression in algae chloroplast has provided new research and advance opportunities for developing low-cost therapeutic proteins. In the present study, algae chloroplast expression system was evaluated for the recombinant production of an anti-cancerous therapeutic protein, Interleukin 29 (IL29). The IL29 gene was cloned into algae chloroplast expression vector (pSRSapI). After the transformation, the positive clones were screened for homoplasmy and the presence of the IL29 gene by spot test and PCR analysis, respectively. The expressed SDS-PAGE and western blotting assay characterized IL-29. The algae expressed IL-29 was biologically active in an anti-proliferating bioassay using HepG2 cells. The results suggest that the Chlamydomonas reinhardtii expression system is convenient, low-cost, eco-friendly, and safe to express IL29.

Clean and folded: Production of active, high quality recombinant human interferon-λ1

Type III interferons exhibit antiviral activity against influenza viruses, coronaviruses, rotaviruses, and others. In addition, this type of interferon theoretically has therapeutic advantages, in comparison with type I interferons, due to its ability to activate a narrower group of genes in a relatively small group of target cells. Hence, it can elicit more targeted antiviral or immunomodulatory responses. Obtaining biologically-active interferon lambda (hIFN-λ₁) is fraught with difficulties at the stage of expression in soluble form or, in the case of expression in the form of inclusion bodies, at the stage of refolding. In this work, hIFN-λ₁ was expressed in the form of inclusion bodies, and a simple, effective refolding method was developed. Efficient and scalable methods for chromatographic purification of recombinant hIFN-λ₁ were also developed. High-yield, high-purity product was obtained through optimization of several processes including: recombinant protein expression; metal affinity chromatography; cation exchange chromatography; and an intermediate protein refolding stage. The obtained protein was shown to feature expected specific biological activity in line with published effects: induction of MxA gene expression in A549 cells and antiviral activity against influenza A virus.

High-level expression and one-step purification of a soluble recombinant human interleukin-37b in Escherichia coli

Interleukin (IL)-37 is a novel member of the IL-1 cytokine family. However, as a result of lacking efficient method to generate relatively large quantity of IL-37, little is known of its functions in man. In the present study, the recombinant human IL-37b containing a C-hexahistidine tag was expressed in Escherichia coli (E. coli). The expression level of IL-37b in E. coli was very high after induction with IPTG. Furthermore, IL-37b protein was largely found in the soluble fraction. The expressed protein was readily purified by one-step immobilized metal-ion affinity chromatography using Ni(2+)-nitrilotriacetic acid agarose. The purified IL-37b appeared as a single band on SDS-PAGE and the purity was more than 97%. The yield was 90mg IL-37b from 1l of bacterial culture. Western blotting and N-terminal sequencing confirmed the identity of the purified protein. The purified IL-37b inhibited significantly the release of tumor necrosis factor-α and IL-1β in lipopolysaccharide-activated THP-1 cells. Thus, this method provides an efficient way to obtain an active IL-37 with high yield and high purity.

Challenges and opportunities in the purification of recombinant tagged proteins

The purification of recombinant proteins by affinity chromatography is one of the most efficient strategies due to the high recovery yields and purity achieved. However, this is dependent on the availability of specific affinity adsorbents for each particular target protein. The diversity of proteins to be purified augments the complexity and number of specific affinity adsorbents needed, and therefore generic platforms for the purification of recombinant proteins are appealing strategies. This justifies why genetically encoded affinity tags became so popular for recombinant protein purification, as these systems only require specific ligands for the capture of the fusion protein through a pre-defined affinity tag tail. There is a wide range of available affinity pairs "tag-ligand" combining biological or structural affinity ligands with the respective binding tags. This review gives a general overview of the well-established "tag-ligand" systems available for fusion protein purification and also explores current unconventional strategies under development.

Interferon-lambdas: the modulators of antivirus, antitumor, and immune responses

IFN-lambdas, including IFN-lambda1, IFN-lambda2, and IFN-lambda3, also known as IL-29, IL-28A, or IL-28B, are a newly described group of cytokines distantly related to the type I IFNs and IL-10 family members. The IFN-lambdaR complex consists of a unique ligand-binding chain, IFN-lambdaR1 (also designated IL-28Ralpha), and an accessory chain, IL-10R2, which is shared with receptors for IL-10-related cytokines. IFN-lambdas signal through the IFN-lambdaR and activate pathways of JAK-STATs and MAPKs to induce antiviral, antiproliferative, antitumor, and immune responses. In this review, we summarize recent findings about the biology of IFN-lambdas and their pathophysiological roles in viral infection, cancer, and immune responses of the innate and adaptive arms.

Phenylalanine biosynthesis in Arabidopsis thaliana. Identification and characterization of arogenate dehydratases

There is much uncertainty as to whether plants use arogenate, phenylpyruvate, or both as obligatory intermediates in Phe biosynthesis, an essential dietary amino acid for humans. This is because both prephenate and arogenate have been reported to undergo decarboxylative dehydration in plants via the action of either arogenate (ADT) or prephenate (PDT) dehydratases; however, neither enzyme(s) nor encoding gene(s) have been isolated and/or functionally characterized. An in silico data mining approach was thus undertaken to attempt to identify the dehydratase(s) involved in Phe formation in Arabidopsis, based on sequence similarity of PDT-like and ACT-like domains in bacteria. This data mining approach suggested that there are six PDT-like homologues in Arabidopsis, whose phylogenetic analyses separated them into three distinct subgroups. All six genes were cloned and subsequently established to be expressed in all tissues examined. Each was then expressed as a Nus fusion recombinant protein in Escherichia coli, with their substrate specificities measured in vitro. Three of the resulting recombinant proteins, encoded by ADT1 (At1g11790), ADT2 (At3g07630), and ADT6 (At1g08250), more efficiently utilized arogenate than prephenate, whereas the remaining three, ADT3 (At2g27820), ADT4 (At3g44720), and ADT5 (At5g22630) essentially only employed arogenate. ADT1, ADT2, and ADT6 had k(cat)/Km values of 1050, 7650, and 1560 M(-1) S(-1) for arogenate versus 38, 240, and 16 M(-1) S(-1) for prephenate, respectively. By contrast, the remaining three, ADT3, ADT4, and ADT5, had k(cat)/Km values of 1140, 490, and 620 M(-1) S(-1), with prephenate not serving as a substrate unless excess recombinant protein (>150 microg/assay) was used. All six genes, and their corresponding proteins, are thus provisionally classified as arogenate dehydratases and designated ADT1-ADT6.

Purification and characterization of prokaryotically expressed human interferon-lambda2

A system for the production of soluble interferon (IFN)-lambda2 was developed by fusing the IFN-lambda2, NusA protein, polyhistidine and S peptide genes and then expressing the fused product (Nus-His-S-tagged IFN-lambda2) in Escherichia coli. The expressed fusion protein was purified by Ni-NTA affinity chromatography. The fusion tag was removed from recombinant IFN-lambda2 by cleavage with enterokinase. N-Terminal sequencing confirmed the identity of the purified protein. When compared with commercial IFN-alpha2b, IFN-lambda2 had similar antiviral activity. The production and characterization of biologically active IFN-lambda2 will be beneficial for its potential role in clinical applications.

On-column refolding purification and characterization of recombinant human interferon-lambda1 produced in Escherichia coli

Interferon-lambda1 (IFN-lambda1) is a member of the recently discovered type III IFNs (IFN-lambda), which possesses antiviral, antitumor, and immunomodulatory activities. In this study, the recombinant human IFN-lambda1 containing a hexahistidine tag was expressed in Escherichia coli. IFN-lambda1 was overexpressed under the control of T7 promoter and most of the protein existed in the form of inclusion bodies. The expressed insoluble protein was solubilized with urea, purified and refolded by one-step immobilized metal-ion affinity chromatography using Ni(2+)-nitrilotriacetic acid agarose. The purified IFN-lambda1 appeared as a single band on SDS-PAGE and the purity was more than 95%. The yield was 86 mg IFN-lambda1 from 1L of bacterial culture. Western blotting and N-terminal sequencing confirmed the identity of the purified protein. The purified IFN-lambda1 exhibited specific antiviral activity as demonstrated by a cytopathic effect reduction assay. Thus, this on-column refolding method provides an efficient way to obtain an active IFN-lambda1 with high yield and high purity.

Production, characterization, and applications of two novel monoclonal antibodies against human interleukin-28A

Interleukin-28A (IL-28A) is a novel cytokine discovered in recent years and has been shown to have antiviral activity. In this study, IL-28A complementary DNA was inserted into prokaryotic expression vector pET-44 Ek/LIC. The Nus-S-His-tagged IL-28A fusion protein was expressed in Escherichia coli BL21 (DE3) in the soluble fraction. The fusion protein was purified by S-protein agarose affinity chromatography, and the fusion tag was removed from recombinant IL-28A by cleavage with thrombin. To prepare specific monoclonal antibody against human IL-28A, BALB/c mice were immunized with IL-28A, and hybridoma cell lines were obtained by fusing mouse spleen cells with myeloma NS-1 cells. Two strains of hybridoma cells, which produced the anti-human IL-28A antibodies 1B9 and 4B5 were obtained. They are IgM isotype and working in western blot analysis and enzyme-linked immunosorbent assay. In the present study, it was shown for the first time that human umbilical vein endothelial cells treated with interferon-alpha and poly(I:C) express IL-28A protein assessed by flow cytometry and immunofluorescent staining techniques. Immunohistochemistry showed that macrophage-like cells in colon and lung tissue and alveolar epithelial cells in lung tissue contain IL-28A, indicating a novel mechanism for both cell types to carry out their antivirus or antitumor functions.