Expression and purification of a recombinant Fip-fve protein from Flammulina velutipes in baculovirus-infected insect cells

Increasing the production of the bioactive compounds in medicinal mushrooms: an omics perspective

Macroscopic fungi, mainly higher basidiomycetes and some ascomycetes, are considered medicinal mushrooms and have long been used in different areas due to their pharmaceutically/nutritionally valuable bioactive compounds. However, the low production of these bioactive metabolites considerably limits the utilization of medicinal mushrooms both in commerce and clinical trials. As a result, many attempts, ranging from conventional methods to novel approaches, have been made to improve their production. The novel strategies include conducting omics investigations, constructing genome-scale metabolic models, and metabolic engineering. So far, genomics and the combined use of different omics studies are the most utilized omics analyses in medicinal mushroom research (both with 31% contribution), while metabolomics (with 4% contribution) is the least. This article is the first attempt for reviewing omics investigations in medicinal mushrooms with the ultimate aim of bioactive compound overproduction. In this regard, the role of these studies and systems biology in elucidating biosynthetic pathways of bioactive compounds and their contribution to metabolic engineering will be highlighted. Also, limitations of omics investigations and strategies for overcoming them will be provided in order to facilitate the overproduction of valuable bioactive metabolites in these valuable organisms.

Functional evaluation of a recombinant fungal immunomodulatory protein from L. rhinocerus produced in P. pastoris and E. coli host expression systems

Fungal immunomodulatory proteins (FIPs) are bioactive proteins with immunomodulatory properties. We previously reported the heterologous production in Escherichia coli of FIP-Lrh from Tiger milk mushroom (Lignosus rhinocerus) with potent cytotoxic effect on cancer cell lines. However, protein produced in E. coli lacks post-translational modifications and may be contaminated with lipopolysaccharide (LPS) endotoxin. Therefore, in this study, yFIP-Lrh produced in Pichia pastoris was functionally compared with eFIP-Lrh produced in E. coli. Expression construct of FIP-Lrh cDNA in pPICZα was generated, transformed into P. pastoris X-33 and Mut⁺ transformants were verified by colony PCR. Induction with 0.5% or 1% methanol resulted in a secreted 13.6 kDa yFIP-Lrh which was subsequently purified and verified using LCMS/MS analysis. Size exclusion chromatography confirmed eFIP-Lrh as a homodimer whereas the larger size of yFIP-Lrh may indicate post-translational modification despite negative for glycoproteins staining. At lower concentration (4-8 μg/mL), yFIP-Lrh induced significantly higher Th1 (IFN-γ, TNF-α) and Th2 (IL-6, IL-4, IL-5, IL-13) cytokines production in mice splenocytes, whereas 16 μg/mL eFIP-Lrh induced significantly higher pro-inflammatory cytokines (TNF-α, IL-6, IL-10), possibly due to higher residual LPS endotoxin (0.082 EU/mL) in eFIP-Lrh compared to negligible level in yFIP-Lrh (0.001 EU/mL). Furthermore, yFIP-Lrh showed higher cytotoxic effect on MCF-7 and HeLa cancer cells. Since both recombinant proteins of FIP-Lrh have the same peptide sequence, besides glycosylation, other post-translational modifications in yFIP-Lrh may account for its enhanced immunomodulatory and anti-proliferative activities. In conclusion, P. pastoris is preferred over E. coli for production of a functionally active yFIP-Lrh devoid of endotoxin contamination. KEY POINTS: • FIP-Lrh can induced production of Th1 and Th2 cytokines by mouse splenocytes. • Higher cytotoxic effect on cancer cells observed for yeast compared to E. coli produced FIP-Lrh. • P. pastoris allows production of an endotoxin-free and functionally active recombinant FIP-Lrh.

New advances and potentials of fungal immunomodulatory proteins for therapeutic purposes

Fungal immunomodulatory proteins (FIPs) are fascinating small and heat-stable bioactive proteins in a distinct protein family due to similarities in their structures and sequences. They are found in fungi, including the fruiting bodies producing fungi comprised of culinary and medicinal mushrooms. Structurally, most FIPs exist as homodimers; each subunit consisting of an N-terminal α-helix dimerization and a C-terminal fibronectin III domain. Increasing numbers of identified FIPs from either different or same fungal species clearly indicates the growing research interests into its medicinal properties which include immunomodulatory, anti-inflammation, anti-allergy, and anticancer. Most FIPs increased IFN-γ production in peripheral blood mononuclear cells, potentially exerting immunomodulatory and anti-inflammatory effects by inhibiting overproduction of T helper-2 (Th2) cytokines common in an allergy reaction. Recently, FIP from Ganoderma microsporum (FIP-gmi) was shown to promote neurite outgrowth for potential therapeutic applications in neuro-disorders. This review discussed FIPs' structural and protein characteristics, their recombinant protein production for functional studies, and the recent advances in their development and applications as pharmaceutics and functional foods.

Optimization of the fermentation parameters for the production of Ganoderma lucidum immunomodulatory protein by Pichia pastoris

In order to obtain a better fermentation parameter for the production of recombinant Ganoderma lucidum immunomodulatory protein (rFIP-glu), an engineered Pichia pastoris GS115 was investigated on the fermentation time, temperature, methanol concentration and initial pH of media, while immunomodulatory activities of the rFIP-glu was confirmed. L₉(3³) orthogonal experiment were firstly employed to optimize various fermentation parameters in the shake-flask level. The optimized fermentation parameters were subsequently verified in a 5 L fermenter. Biological activities including cell viability and tumor necrosis factor-alpha (TNF-α) mRNA of the rFIP-glu were evaluated on murine macrophage RAW264.7 cells. The results showed that the yield of rFIP-glu was up to 368.71 μg/ml in the shake-flask, and 613.47 μg/ml in the 5 L fermenter, when the Pichia pastoris was incubated in basic media with the methanol concentration 1.0% and initial pH 6.5, and with constant shaking at 280 rpm for 4 days at 26 °C. In vitro assays of biological activity indicated that rFIP-glu had significant toxicity against RAW264.7 cells, and possessed the ability to induce TNF-α mRNA expression in macrophage RAW264.7 cells. In conclusion, engineered P. pastoris showed a good fermentation property under the optimum fermentation parameters. It could be a candidate industrial strain for further study.

Ganoderma proteins and their potential applications in cosmetics

Ganoderma have been regarded as a traditional source of natural bioactive compounds for centuries and have recently been exploited for potential components in the cosmetics industry. Besides Ganoderma polysaccharides and triterpenes, multiple proteins have been found in Ganoderma. With the in-depth study of these proteins, various pharmacological functions of Ganoderma have become important in the discovery and development of new products. In the review, we summarized and discussed the kinds and characteristics of Ganoderma proteins, especially on fungal immunomodulatory proteins (FIPs) which can be potentially developed into cosmeceuticals or nutricosmetics and are a suitable target for production using established biotechnological methods. Furthermore, we discuss their pharmacological activities of the proteins with a focus on their pharmacological functions related to cosmetics, such as antioxidant activity, inhibition of melanin, antibacterial activity, and regulation of inflammatory mediators. Numerous other questions also are addressed before the proteins can be widely accepted and used as cosmetic additives.

Combination of on-line desalting and HPLC-UV-ESI-MS for simultaneous detection and identification of FIP-fve and flammutoxin in Flammulina velutipes

A rapid analytical approach, on-line desalting HPLC-UV-ESI-MS method, for the analysis of FIP-fve and flammutoxin (FTX), two important bioactive proteins in the fruiting bodies of Flammulina velutipes, was developed. In this study, a highly efficient desalting method is provided using molecular weight cut-off centrifugal filtration and on-line desalting. Sample preparation followed by an on-line desalting HPLC-UV-ESI-MS system was employed for simultaneous desalting and detection and identification of FIP-fve and FTX. Results indicated that using trifluoroacetic acid as a modifier on a C18 reversed-phase column renders effective separation. ESI-MS revealed that the apparent molecular masses of FIP-fve and FTX were 12,749.1 Da and 21,912.5 Da, respectively. Eleven milligrams of FIP-fve was obtained from 100 g of fresh fruiting bodies, and UV detection was performed at 280 nm using bovine serum albumin as the standard protein. The calibration curve was linear in the concentration range of 0.29–4.69 mg/mL (r² = 0.9999). FTX and a series of degradation products were isolated from F. velutipes using 35% saturated ammonium sulfate on a DEAE cellulose column. The complete identification of FTX and a series of degradation products were carried out by precipitation of various ammonium sulfate concentrations (0–45%, 45–65% and 65–90%), in-gel trypsin digestion, and MS analysis with combined database search. The molecular weights of FTX and a series of degradation products were 29,957.2 Da, 27,480.2 Da, 26,512.5 Da, and 21,912.5 Da.

Identification and functional characterization of a novel fungal immunomodulatory protein from Postia placenta

In this study, a previously unknown fungal immunomodulatory protein (FIP), here called FIP-ppl, was identified from the basidiomycete fungus Postia placenta by searching its genome sequence database using known FIPs as baits, which was the first basidiomycete FIP to be identified outside the order of edible macro fungi. The gene FIP-ppl was synthesized and expressed in Escherichia coli to produce a glutathione S-transferase (GST) fusion protein. The fusion protein was purified on a GST affinity column and the protein tag was removed using in situ thrombin cleavage. The purified recombinant protein (rFIP-ppl) displayed hemagglutination activity toward rabbit red blood cells but not against human red blood cells. RFIP-ppl stimulated mouse splenocyte cell proliferation and enhanced interleukin-2 (IL-2) release. Antitumor assays indicated that rFIP-ppl had significant cell proliferation inhibitory activity and apoptotic effects in human tumor cells with more pronounced inhibiting proliferation and inducing apoptotic effects on gastric tumor cells (MGC823) than against hepatoma (HepG2) cells. This study confirms an alternative means of identifying, producing, and isolating new FIPs. It may provide convenient access to FIP-ppl with potential human therapeutic applications.

Recombinant expression of a novel fungal immunomodulatory protein with human tumor cell antiproliferative activity from Nectria haematococca

To our best knowledge, all of the fungal immunomodulatory proteins (FIPs) have been successfully extracted and identified in Basidomycetes, with only the exception of FIP from ascomycete Nectria haematococca (FIP-nha) discovered through homology alignment most recently. In this work, a gene encoding FIP-nha was synthesized and recombinantly expressed in an Escherichia coli expression system. SDS-PAGE and MALDI-MS analyses of recombinant FIP-nha (rFIP-nha) indicated that the gene was successfully expressed. The yield of the bioactive FIP-nha protein was 42.7 mg/L. In vitro assays of biological activity indicated that the rFIP-nha caused hemagglutination of human and rabbit red blood cells, significantly stimulated mouse spleen lymphocyte proliferation, and enhanced expression of interleukin-2 (IL-2) released from mouse splenocytes, revealing a strong antitumor effect against HL60, HepG2 and MGC823. Through this work, we constructed a rapid and efficient method of FIP production, and suggested that FIP-nha is a valuable candidate for use in future medical care and pharmaceutical products.

Cloning and analysis of a functional promoter of fungal immunomodulatory protein from Flammulina velutipes

Fugal immunomodulatory protein from Flammulina velutipes (FIP-fve) belongs to FIPs family, which has precious pharmaceutical value. To understand the regulatory mechanism of FIP-fve expression, we have cloned a 900 bp genomic DNA fragment from the transcriptional start site of the FIP-fve gene using genomic walker technology. Sequence analysis showed the presence of several eukaryotic transcription factor binding motifs in the 900 bp of upstream region of the FIP-fve gene, which contains one putative TATA-boxes, four possible CAAT-boxes, one ABRE, one ARE, three CGTCA-motifs, two TGA-elements and four Skn-1 motifs. The eukaryotic expression vector pfveP:: GUS-GFP was transferred into tobacco via an agrobacterium-mediated leaf disc transformation. The results showed that the FIP-fve promoter could induce the reporter gene GUS or GFP expression in different tissues of tobaccos. This study would lay a foundation for expression regulation of FIP-fve and development of genetic-modified plant products.

Cytotoxic effect of novel Flammulina velutipes sterols and its oral bioavailability via mixed micellar nanoformulation

The aim of this study was to investigate the anti-tumor effect of sterols initially separated from Flammulina velutipes and the pharmacokinetics and tissue distribution after oral administration of F. velutipes sterol nanomicelles (FVSNs). F. velutipes sterol (FVS) consisted of mainly ergosterol (54.78%), 22,23-dihydroergosterol (27.94%) and ergost-8(14)-ene-3β-ol (discovered for the first time in F. velutipes). In vitro cytotoxicity assay of FVS against U251 cells and HeLa cells showed that at 72h treatment, the FVS (IC50=23.42μg/mL) exhibited strong inhibitory effect against U251 cells, even overwhelmed the standard anti-tumor drug (5-fluorouracil) to an extent, while the HeLa cells were not significantly susceptible to the FVS. To improve the solubility and bioavailability of FVS, a model for insoluble anti-tumor drugs, FVSNs were prepared. In vitro characterization of FVSNs revealed satisfactory size distribution, loading capacity and encapsulation efficiency. Pharmacokinetic study in SD rats demonstrated that the mixed micellar nanoformulation significantly enhanced the bioavailability of FVS than free drug. Additionly, tissue distribution in mice manifested that the biodistribution of FVSNs as compared to the free FVS suspension were significantly improved. In conclusion, the nanomicelles developed in our study provided a promising delivery system for enhancing the oral bioavailability and selective biodistribution of FVS, a potential anti-tumor agent.

High-Yield Production in Escherichia coli of Fungal Immunomodulatory Protein Isolated from Flammulina velutipes and Its Bioactivity Assay in Vivo

A fungal immunomodulatory protein isolated from Flammulina velutipes (FIP-fve) has structural similarity to the variable region of the immunoglobulin heavy chain. In the present study, the recombinant bioactive FIP-fve protein with a His-tag in N-terminal of recombinant protein was expressed in transetta (DE3) at a high level under the optimized culturing conditions of 0.2 mM IPTG and 28 °C. The efficiency of the purification was improved with additional ultrasonication to the process of lysozyme lysis. The yield of the bioactive FIP-fve protein with 97.1% purity reached 29.1 mg/L with a large quantity for industrial applications. Enzyme-linked immunosorbent assay showed a maximum increase in interleukin-2 (IL-2) and gamma interferon (IFN-γ) for the mice serum group of 5 mg/kg body mass (p < 0.01) with three doses of His-FIP-fve. However, the production of IL-4 had no apparent difference compared to the control.

Recent status and prospects of the fungal immunomodulatory protein family

With the exception of polysaccharides and triterpenes/triterpenoids compounds, fungal immunomodulatory protein (FIP), a small molecule protein, is also an important bioactive component with immune regulating activity. It plays a significant role in immunomodulating. The objective of this paper was to review the latest advances in various aspects of research on FIPs, including their basic components and structural character, characters of diversity, gene cloning and expression, and their biological function, etc. In addition, prospects of utilization value and the exploitation foreground of FIPs were also discussed. The review will provide a useful reference for further research, development, and utilizations of FIPs.

Heterologous expression of the immunomodulatory protein gene from Ganoderma sinense in the basidiomycete Coprinopsis cinerea

AIMS

FIP-gsi, a fungal immunomodulatory protein found in Ganoderma sinense, has antitumour, anti-allergy and immunomodulatory activities and is regulated by the fip-gsi gene. In this study, we aimed to express the fip-gsi gene from G. sinense in Coprinopsis cinerea to increase yield of FIPs-gsi.

METHODS AND RESULTS

A fungal expression vector pBfip-gsi containing the gpd promoter from Agaricus bisporus and the fip-gsi gene from the G. sinense was constructed and transformed into C. cinerea. PCR and Southern blotting analysis verified the successful integration of the exogenous gene fip-gsi into the genome of C. cinerea. RT-PCR and Northern blotting analysis confirmed that the fip-gsi gene was transcribed in C. cinerea. The yield of the FIP-gsi protein reached 314mg kg(-1) fresh mycelia. The molecular weight of the FIP-gsi was 13kDa, and the FIP-gsi was capable of hemagglutinating mouse red blood cells, but no such activity was observed towards human red blood cells in vitro.

CONCLUSIONS

The fip-gsi from G. sinense has been successfully translated in C. cinerea, and the yield of bioactive FIP-gsi protein was high.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report using the C. cinerea for the heterologous expression of FIP-gsi protein and it might supply a basis for large-scale production of the protein.

Influenza virus-like particles as an antigen-carrier platform for the ESAT-6 epitope of Mycobacterium tuberculosis

Various virus-like particles (VLPs) have been shown to induce cytotoxic T-cell immune response as well as B-cell immune response. This makes VLPs promising candidates for antigen-carrier platforms for various epitopes. Influenza A VLPs were produced displaying a 20 amino acid sequence from Mycobacterium tuberculosis early secretory antigenic target 6 protein (ESAT-6). As this sequence is known to comprise a potent T-cell epitope it was chosen as a model for a foreign epitope to be presented on an influenza VLP scaffold. The ESAT-6 epitope was engineered into the antigenic region B of the influenza hemagglutinin (HA) from strain A/New Caledonia/20/99. VLPs were expressed in insect cells and subjected to immunization studies in mice. High serum antibody titers detected against recombinant ESAT-6 demonstrated the feasibility of influenza A VLPs serving as an efficient platform for epitope presentation.

Augmentation of regulatory T cells in allergic individuals by recombinant Der f 2 peptide with fungal immunomodulatory peptide fve

BACKGROUND

The suppressive function of regulatory T (Treg) cells is compromised in allergic individuals, and the augmentation of Treg cells has been demonstrated after successful allergen immunotherapy.

OBJECTIVE

To evaluate the effect of Dermatophagoides farinae fragments (Der f 2 N-peptides) that do not bind specific IgE in conjunction with the fungal immunomodulatory peptide fve (FIP-fve) on Treg cells derived from individuals with allergic rhinitis.

METHODS

CD4+CD25+ T cells were isolated from peripheral blood mononuclear cells of 11 patients with allergic rhinitis and 7 nonallergic individuals using immunomagnetic beads. Cells were cultured with medium, Der f 2, FIP-fve, FIP-fve plus Der f 2, and FIP-fve plus Der f 2 N-peptides for 6 days in the presence of antigen-presenting cells. The percentages and function of Foxp3+CD4+CD25+ Treg cells, interleukin (IL) 10+, and transforming growth factor beta (TGF-beta)+ Treg cells were measured.

RESULTS

The percentage of Foxp3+ Treg cells in CD4+CD25+ T cells was significantly increased in D farinae allergic patients by Der f 2 N-peptides in conjunction with FIP-fve. Both IL-10+ and TGF-beta+ Treg cells were significantly increased in the presence of Der f 2 N-peptides and FIP-fve compared with other groups. The function of Treg cells induced by Der f 2 N-peptides and FIP-fve could be demonstrated by the inhibition of bromodeoxyuridine uptake by peripheral blood mononuclear cells.

CONCLUSION

The percentage of IL-10+ and TGF-beta+ cells in Foxp3+CD4+CD25+ T cells can be up-regulated by Der f 2 N-peptides in conjunction with FIP-fve only in D farinae allergic individuals. These results indicate that non-IgE-mediated fragments of allergen in conjunction with FIP-fve might have therapeutic effects on Treg cells derived from allergic individuals.