Expression, purification, and characterization of recombinant human L-chain ferritin

Thymol Induces Fenton-Reaction-Dependent Ferroptosis in Vibrio parahemolyticus

Thymol has efficient bactericidal activity against a variety of pathogenic bacteria, but the bactericidal mechanism against Vibrio parahemolyticus (V. parahemolyticus) has rarely been reported. In the current study, we investigated the bactericidal mechanism of thymol against V. parahemolyticus. The Results revealed that 150 μg/mL of thymol had 99.9% bactericidal activity on V. parahemolyticus. Intracellular bursts of reactive oxygen species (ROS), Fe2+accumulation, lipid peroxidation, and DNA breakage were checked by cell staining. The exogenous addition of H2O2 and catalase promoted and alleviated thymol-induced cell death to a certain extent, respectively, and the addition of the ferroptosis inhibitor Liproxstatin-1 also alleviated thymol-induced cell death, confirming that thymol induced Fenton-reaction-dependent ferroptosis in V. parahemolyticus. Proteomic analysis revealed that relevant proteins involved in ROS production, lipid peroxidation accumulation, and DNA repair were significantly upregulated after thymol treatment. Molecular docking revealed two potential binding sites (amino acids 46H and 42F) between thymol and ferritin, and thymol could promote the release of Fe2+ from ferritin proteins through in vitro interactions analyzed. Therefore, we hypothesized that ferritin as a potential target may mediate thymol-induced ferroptosis in V. parahemolyticus. This study provides new ideas for the development of natural inhibitors for controlling V. parahemolyticus in aquatic products.

Advancements of the Molecular Directed Design and Structure-Activity Relationship of Ferritin Nanocage

Ferritin nanocages possess remarkable structural properties and biological functions, making them highly attractive for applications in functional materials and biomedicine. This comprehensive review presents an overview of the molecular characteristics, extraction and identification of ferritin, ferritin receptors, as well as the advancements in the directional design of high-order assemblies of ferritin and the applications based on its unique structural properties. Specifically, this Review focuses on the regulation of ferritin assembly from one to three dimensions, leveraging the symmetry of ferritin and modifications on key interfaces. Furthermore, it discusses targeted delivery of nutrition and drugs through facile loading and functional modification of ferritin. The aim of this Review is to inspire the design of micro/nano functional materials using ferritin and the development of nanodelivery vehicles for nutritional fortification and disease treatment.

Soluble expression and purification of recombinant bovine ferritin H-chain

Ferritin is a potential medicine delivery vehicle and vaccine platform, and its efficient expression is a prerequisite for widespread application. This study introduces a soluble expression strategy for recombinant bovine ferritin heavy chain (rFTH) in a prokaryotic system and an improved protein purification method. The amplified rFTH gene was ligated into the prokaryotic expression vector pET30a. The recombinant vectors with the N-terminal His-tag(N-His) or C-terminal His-tag(C-His) were translated and expressed separately. The results showed that the solubility of rFTH with C-His was significantly higher than that with N-His. The expression of rFTH with C-His was attempted at 37 °C and 16 °C, respectively. The results showed that the proportion of soluble protein expressed at 37 °C was more than 90%, higher than that expressed at 16 °C. Then rFTH with C-His was purified successfully using anion exchange chromatography, modified PEG precipitation, and dialysis. The rFTH protein was characterized using SDS-PAGE, Native-PAGE, Western blot, transmission electron microscopy, and dynamic light scattering. The results demonstrated that the purified rFTH protein self-assembled into ferritin nanoparticles with a regular shape and uniform size. This study sheds new light on the soluble expression of ferritin and provides a foundation for the construction of bovine ferritin nanoparticle production platforms.

Manufacturing of non-viral protein nanocages for biotechnological and biomedical applications

Protein nanocages are highly ordered nanometer scale architectures, which are typically formed by homo- or hetero-self-assembly of multiple monomers into symmetric structures of different size and shape. The intrinsic characteristics of protein nanocages make them very attractive and promising as a biological nanomaterial. These include, among others, a high surface/volume ratio, multi-functionality, ease to modify or manipulate genetically or chemically, high stability, mono-dispersity, and biocompatibility. Since the beginning of the investigation into protein nanocages, several applications were conceived in a variety of areas such as drug delivery, vaccine development, bioimaging, biomineralization, nanomaterial synthesis and biocatalysis. The ability to generate large amounts of pure and well-folded protein assemblies is one of the keys to transform nanocages into clinically valuable products and move biomedical applications forward. This calls for the development of more efficient biomanufacturing processes and for the setting up of analytical techniques adequate for the quality control and characterization of the biological function and structure of nanocages. This review concisely covers and overviews the progress made since the emergence of protein nanocages as a new, next-generation class of biologics. A brief outline of non-viral protein nanocages is followed by a presentation of their main applications in the areas of bioengineering, biotechnology, and biomedicine. Afterwards, we focus on a description of the current processes used in the manufacturing of protein nanocages with particular emphasis on the most relevant aspects of production and purification. The state-of-the-art on current characterization techniques is then described and future alternative or complementary approaches in development are also discussed. Finally, a critical analysis of the limitations and drawbacks of the current manufacturing strategies is presented, alongside with the identification of the major challenges and bottlenecks.

Simple plant-based production and purification of the assembled human ferritin heavy chain as a nanocarrier for tumor-targeted drug delivery and bioimaging in cancer therapy

Nanoparticles are used as carriers for the delivery of drugs and imaging agents. Proteins are safer than synthetic nanocarriers due to their greater biocompatibility and the absence of toxic degradation products. In this context, ferritin has the additional benefit of inherently targeting the membrane receptor transferrin 1, which is overexpressed by most cancer cells. Furthermore, this self-assembling multimeric protein can be loaded with more than 2000 iron atoms, as well as drugs, contrast agents, and other cargos. However, recombinant ferritin currently costs ~3.5 million € g^-1 , presumably because the limited number of producers cannot meet demand, making it generally unaffordable as a nanocarrier. Because plants can produce proteins at very-large-scale, we developed a simple, proof-of-concept process for the production of the human ferritin heavy chain by transient expression in Nicotiana benthamiana. We optimized the protein yields by screening different compartments and 5'-untranslated regions in PCPs, and selected the best-performing construct for production in differentiated plants. We then established a rapid and scalable purification protocol by combining pH and heat treatment before extraction, followed by an ultrafiltration/diafiltration size-based separation process. The optimized process achieved ferritin levels of ~40 mg kg^-1 fresh biomass although depth filtration limited product recovery to ~7%. The purity of the recombinant product was >90% at costs ~3% of the current sales price. Our method therefore allows the production of affordable ferritin heavy chain as a carrier for therapeutic and diagnostic agents, which is suitable for further stability and functionality testing in vitro and in vivo.

Production of Recombinant Human Hybrid Ferritin with Heavy Chain and Light Chain in Escherichia coli and its Characterization

BACKGROUND

Natural human ferritin generally contains 24 subunits with different ratios of heavy chain to light chain, and the ratio of both subunits varies depending on tissue distribution and pathological conditions. However, the production of recombinant hybrid ferritin with both subunits is more challenging.

OBJECTIVE

This study aimed to prepare the recombinant hybrid ferritin for prokaryotic expression and characterize its structure and physicochemical properties.

METHODS

A prokaryotic expression vector of pACYCDuet-1 harboring the two individual genes of human ferritin heavy chain and light chain (FTH/FTL-pACYCDuet-1) was constructed and transfected into Escherichia coli bacteria. Then the genes were co-induced by IPTG to express.

RESULTS

The ferritin was purified by hydrophobic interaction chromatography combining size exclusion chromatography and verified by mass spectrometry and characterized by spectral and morphological analysis.

CONCLUSION

FTH and FTL subunits were successfully co-assembled into a hybrid ferritin nanoparticle (rhFTH/L). The structure of rhFTH/L was demonstrated highly ordered and fairly compact. Besides, the hybrid rhFTH/L nanoparticle was shown more sensitive to thermal stress and reduced stability when compared with that of both individual rhFTH and rhFTL.

Conversion of recombinant human ferritin light chain inclusion bodies into uniform nanoparticles in Escherichia coli for facile production

Prokaryotic expression systems are widely used to produce many types of biologics because of their extreme conveniences and unmatchable cost. However, production of recombinant human ferritin light chain (rhFTL) protein is largely restrained because its expression in Escherichia coli tends to form inclusion bodies (IBs). In this study, a prokaryotic expression vector (FTL-pBV220) harboring the rhFTL gene was constructed using a pBV220 plasmid. The tag-free rhFTL was highly expressed and almost entirely converted to soluble form, and thus the rhFTL was successfully self-assembled into uniform nanoparticles in E. coli. To establish a simplified downstream process, a precipitation procedure based on the optimized incubation temperature, pH condition, and ionic strength was developed to remove impurities from the crude lysate supernatant. The rhFTL retained in the clarified supernatant was subsequently purified in a single step using Capto Butyl column resulting in a considerable recovery and high purity. The purified rhFTL was characterized and verified by mass spectrometry and spectral and morphological analyses. The results revealed that rhFTL exhibited highly ordered and fairly compact structures and the spherical structures were preserved.

PM1-loaded recombinant human H-ferritin nanocages: A novel pH-responsive sensing platform for the identification of cancer cells

The aggregation-induced emission (AIE) material has been widely used in biological detection due to their unique property of fluorescing in aggregation state. However, the poor dispersion and biocompatibility limit its application in in vivo real-time imaging. Here, a novel strategy is designed to obtain pH-responsive AIE nanomaterials, working through 4-Undecoxy Tetraphenyl Ethylene Methacrylate (PM1) block, with excellent features (dispersion, biocompatibility, self-reconstruction and cancer specific recognition). The recombinant human H-ferritin (rHuHF) was used to prepare rHuHF-PM1 nanocomposites which effectively supported the dispersion and transfer of PM1 in the biological environment, even making it target tumor cells due to the overexpression of ferritin receptors on tumor cells. To simulate the changes of rHuHF in intracellular lysosomes, particle size and fluorescence of rHuHF-PM1 were analyzed, which reflected the loose structural changes of rHuHF nanocages in weak acid system that facilitated the degradation of macromolecular rHuHF in intracellular lysosomes and following release of PM1. The released PM1 molecules aggregated and emitted brilliant blue fluorescence. Several cell lines, Hela, HT-29, HepG2, L-O2 and HUVEC have all been sensitively detected and distinguished. Accordingly, this nanocage has a potential to be applied to disease diagnosis and provides a novel sensing platform for the identification of cancer.

Apoferritin and Dps as drug delivery vehicles: Some selected examples in oncology

BACKGROUND

The ideal nanoparticle should be able to encapsulate either pharmaceutical agents or imaging probes so that it could treat or image clinical tumours by targeting the cancer site efficiently. Further, it would be an added advantage if it demonstrates: small size, built in targeting, biocompatibility and biodegradability. Ferritin, which is an endogenous self-assembling protein, stores iron and plays a role in iron homeostasis. When iron atoms are removed apoferritin (AFt) is formed which consists of a hollow shell where it can be used to load guest molecules. Due to its unique architecture, AFt has been investigated as a versatile carrier for tumour theranostic applications. DNA-binding protein from starved cells (Dps), which also belongs to the ferritin family, is a protein found only in prokaryotes. It is used to store iron and protect chromosomes from oxidative damage; because of its architecture, Dps could also be used as a delivery vehicle.

CONCLUSIONS

Both these nano particles are promising in the field of oncology, especially due to their stability, solubility and biocompatibility features. Further their exterior surface can be modified for better tumour-targeting ability. More studies, are warranted to determine the immunogenicity, biodistribution, and clearance from the body.

GENERAL PERSPECTIVE

This review discusses a few selected examples of the remarkable in vitro and in vivo studies that have been carried out in the recent past with the use of AFt and Dps in targeting and delivery of various pharmaceutical agents, natural products and imaging probes in the field of oncology.

Functionalizing Ferritin Nanoparticles for Vaccine Development

In the last decade, the interest in ferritin-based vaccines has been increasing due to their safety and immunogenicity. Candidates against a wide range of pathogens are now on Phase I clinical trials namely for influenza, Epstein-Barr, and SARS-CoV-2 viruses. Manufacturing challenges related to particle heterogeneity, improper folding of fused antigens, and antigen interference with intersubunit interactions still need to be overcome. In addition, protocols need to be standardized so that the production bioprocess becomes reproducible, allowing ferritin-based therapeutics to become readily available. In this review, the building blocks that enable the formulation of ferritin-based vaccines at an experimental stage, including design, production, and purification are presented. Novel bioengineering strategies of functionalizing ferritin nanoparticles based on modular assembly, allowing the challenges associated with genetic fusion to be circumvented, are discussed. Distinct up/down-stream approaches to produce ferritin-based vaccines and their impact on production yield and vaccine efficacy are compared. Finally, ferritin nanoparticles currently used in vaccine development and clinical trials are summarized.

A Review: Molecular Chaperone-mediated Folding, Unfolding and Disaggregation of Expressed Recombinant Proteins

The advancements in biotechnology over time have led to an increase in the demand of pure, soluble and functionally active proteins. Recombinant protein production has thus been employed to obtain high expression of purified proteins in bulk. E. coli is considered as the most desirable host for recombinant protein production due to its inexpensive and fast cultivation, simple nutritional requirements and known genetics. Despite all these benefits, recombinant protein production often comes with drawbacks, such as, the most common being the formation of inclusion bodies due to improper protein folding. Consequently, this can lead to the loss of the structure-function relationship of a protein. Apart from various strategies, one major strategy to resolve this issue is the use of molecular chaperones that act as folding modulators for proteins. Molecular chaperones assist newly synthesized, aggregated or misfolded proteins to fold into their native conformations. Chaperones have been widely used to improve the expression of various proteins which are otherwise difficult to produce in E. coli. Here, we discuss the structure, function, and role of major E. coli molecular chaperones in recombinant technology such as trigger factor, GroEL, DnaK and ClpB.

Advancements of nature nanocage protein: preparation, identification and multiple applications of ferritins

Ferritin is an important iron storage protein, which is widely existed in all forms of life. Ferritin can regulate iron homeostasis when iron ions are lacking or enriched in the body, so as to avoid iron deficiency diseases and iron poisoning. Ferritin presents a hollow nanocage, which can store ions or other small molecular substances in the cavity. Therefore, ferritin shows its potential as a functional nanomaterial that can deliver nutrients or drugs in a targeted manner to improve bioavailability. Due to the special structure, the research on ferritin has attracted more and more attention in recent years. In this paper, the structural characteristics of ferritin were introduced, and the natural purification and prokaryotic expression methods of ferritin from different sources were described. At the same time, ferritin can bind to small molecules, so that it has the activity of small molecules, to construct a new type of ferritin. As a result, ferritin plays an important role as a nutrient substance, in targeted transport, and disease monitoring, etc. In conclusion, the yield of ferritin can be improved by means of molecular biology. Meanwhile, molecular modification can be used to make ferritin have unique activity and function, which lays a foundation for subsequent research. HighlightsThe molecular and structural properties of ferritins were clearly described.Isolation and purification technologies of ferritin were compared.Characterization, functions and molecular modifications mechanism of ferritin were reviewed.The applications of ferritin in pharmaceutical and food industry were prospected.

Expression, purification, and characterisation of recombinant ferritin in insect cells using the baculovirus expression system

OBJECTIVE

Ferritin is an attractive vector for the delivery of drug molecules and antigen proteins because of its unique structural and biochemical features. In this study, recombinant ferritin from Helicobacter pylori was expressed in the soluble form employing the baculovirus expression system.

RESULTS

The optimum conditions for producing recombinant ferritin comprised MOI 5 of rBV-ferritin for 96 h of infection. The recombinant ferritin was purified by Ni Sepharose™ 6 Fast Flow, with a purity and yield of 92.5% and 11.25 mg/L, respectively. In addition, the recombinant ferritin showed a multimeric structure under non-denaturing conditions, as well as self-assembled spherical cage architecture with a diameter of approximately 12 nm. Dot-ELISA results suggested that the His-tag at the N-terminus likely existed on the surface of the recombinant ferritin.

CONCLUSION

Recombinant ferritin was produced by the baculovirus expression system, which has the potential to display exogenous proteins, and may aid in the delivery of drugs for disease prevention and treatment.

Ferritin Nanocages with Biologically Orthogonal Conjugation for Vascular Targeting and Imaging

Genetic incorporation of biologically orthogonal functional groups into macromolecules has the potential to yield efficient, controlled, reproducible, site-specific conjugation of affinity ligands, contrast agents, or therapeutic cargoes. Here, we applied this approach to ferritin, a ubiquitous iron-storage protein that self-assembles into multimeric nanocages with remarkable stability, size uniformity (12 nm), and endogenous capacity for loading and transport of a variety of inorganic and organic cargoes. The unnatural amino acid, 4-azidophenylalanine (4-AzF), was incorporated at different sites in the human ferritin light chain (hFTL) to allow site-specific conjugation of alkyne-containing small molecules or affinity ligands to the exterior surface of the nanocage. The optimal positioning of the 4-AzF residue was evaluated by screening a library of variants for the efficiency of copper-free click conjugation. One of the engineered ferritins, hFTL-5X, was found to accommodate ∼14 small-molecule fluorophores (AlexaFluor 488) and 3-4 IgG molecules per nanocage. Intravascular injection in mice of radiolabeled hFTL-5X carrying antibody to cell adhesion molecule ICAM-1, but not control IgG, enabled specific targeting to the lung due to high basal expression of ICAM-1 (43.3 ± 6.99 vs 3.48 ± 0.14%ID/g for Ab vs IgG). Treatment of mice with endotoxin known to stimulate inflammatory ICAM-1 overexpression resulted in 2-fold enhancement of pulmonary targeting (84.4 ± 12.89 vs 43.3 ± 6.99%ID/g). Likewise, injection of fluorescent, ICAM-targeted hFTL-5X nanocages revealed the effect of endotoxin by enhancement of near-infrared signal, indicating potential utility of this approach for both vascular targeting and imaging.

New findings in potential applications of tobacco osmotin

The osmotin protein is involved in both monocot and dicot plant responses to biotic and abiotic stress. To determine the biological activity of osmotin, the gene was amplified from tobacco genomic DNA, fused with the hexahistidine tag motif and successfully expressed in Escherichia coli, after which the recombinant osmotin was purified and renatured. Various activities were then tested, including hemolytic activity, toxicity against human embryonic kidney cells, and the antifungal activity of the recombinant osmotin. We found that osmotin had no adverse effects on human kidney cells up to a concentration of 500 μg.ml-1. However, the purified osmotin also had significant antimicrobial activity, specifically against fungal pathogens causing candidiasis and otitis, and against the common food pathogens. Using the osmotin-Agrobacterium construct, the osmotin gene was inserted into tobacco plants in order to facilitate the isolation of recombinant protein. Using qPCR, the presence and copy number of the transgene was detected in the tobacco plant DNA. The transgene was also quantified using mRNA, and results indicated a strong expression profile, however the native protein has been never isolated. Once the transgene presence was confirmed, the transgenic tobacco plants were grown in high saline concentrations and monitored for seed germination and chlorophyll content as indicators of overall plant health. Results indicated that the transgenic tobacco plants had a higher tolerance for osmotic stress. These results indicate that the osmotin gene has the potential to increase crop tolerance to stresses such as fungal attack and unfavorable osmotic conditions.