Optimization of expression and purification of HSPA6 protein from Camelus dromedarius in E. coli

Expression and purification of recombinant tilapia lake virus segment 4 protein and its in-vitro biological activity for potential use in vaccine development

Tilapia lake virus (TiLV) disease is highly contagious and causes substantial mortality in tilapia. Currently, no effective treatments or commercial vaccines are available to prevent TiLV infection. In this study, TiLV segment 4 (S4) was cloned into the pET28a(+)vector and transformed into Escherichia coli BL21(DE3). Codon optimization was performed to enhance TiLV S4 protein expression, and a range of expression conditions were tested, including various inducers and postinduction temperatures and times for both soluble and insoluble protein expression. The recombinant TiLV S4 protein was purified using affinity chromatography. The optimal conditions for recombinant TiLV S4 expression were achieved via induction using 0.1 mM galactose at 37 °C for 1 h postinduction. The insoluble protein was denatured using 6 M urea and subsequently purified to yield a protein concentration of approximately 250 mg/L. Dot blot immunodetection assays confirmed consistent interactions between the purified TiLV S4 protein and the sera from infected fish and rabbit anti-TiLV antibodies. By identifying the optimal growth conditions and production factors for the recombinant protein, our study offers valuable information for the large-scale production of the TiLV S4 protein, which signals an important step forward in TiLV vaccine development.

Elucidation of kinetic and structural properties of eye lens ζ-crystallin: an in vitro and in silico approach

The Arabian Camelus dromedarius contains significant concentration of eye lens ζ-crystallin. This enzyme is also present in other life forms including humans, however in lower catalytic amounts. The recombinant camel ζ-crystallin was expressed in the E. coli BL21 (DE3) pLysS strain and purified using HisTrap column. The K_m of the enzyme for 9,10-phenanthrenequinone (9,10-PQ) substrate and NADPH cofactor was determined to be 11.66 and 50.93 µM, respectively. The V_max for 9,10-PQ and NADPH was obtained as 23.19 and 19.98 μM min^-1, respectively. The optimum activity of the purified enzyme was found to be at pH 6.0 and at 55 °C. Different physico-chemical parameters were analysed including instability index (II), aliphatic index (AI) and the GRAVY index to establish proper characterization. The sequence of the recombinant ζ-crystallin was subjected to homology modelling using SWISS-MODEL webserver followed by validation of the modelled target structure. The evaluation of the modelled ζ-crystallin was performed by several parameters including Ramachandran plot, Z-score values followed by molecular dynamics (MD) simulation. The cumulative analysis of the physico-chemical, quantitative, qualitative and the essential dynamics of simulation of ζ-crystallin and its complexes with 9,10-PQ and NADPH helped in verifying the acceptable quality and stability of the ζ-crystallin structure.Communicated by Ramaswamy H. Sarma.

Optimization of an Inclusion Body-Based Production of the Influenza Virus Neuraminidase in Escherichia coli

Neuraminidase (NA), as an important protein of influenza virus, represents a promising target for the development of new antiviral agents for the treatment and prevention of influenza A and B. Bacterial host strain Escherichia coli BL21 (DE3)pLysS containing the NA gene of the H1N1 influenza virus produced this overexpressed enzyme in the insoluble fraction of cells in the form of inclusion bodies. The aim of this work was to investigate the effect of independent variables (propagation time, isopropyl β-d-1-thiogalactopyranoside (IPTG) concentration and expression time) on NA accumulation in inclusion bodies and to optimize these conditions by response surface methodology (RSM). The maximum yield of NA (112.97 ± 2.82 U/g) was achieved under optimal conditions, namely, a propagation time of 7.72 h, IPTG concentration of 1.82 mM and gene expression time of 7.35 h. This study demonstrated that bacterially expressed NA was enzymatically active.

Rational design of a new variant of Reteplase with optimized physicochemical profile and large-scale production in Escherichia coli

Structural engineering of the recombinant thrombolytic drug, Reteplase, and its cost-effective production are important goals in the pharmaceutical industry. In this study, a single-point mutant of the protein was rationally designed and evaluated in terms of physicochemical characteristics, enzymatic activity, as well as large-scale production settings. An accurate homology model of Reteplase was used as the input to appropriate tools to identify the aggregation-prone sites, while considering the structural stability. Selected variants underwent extensive molecular dynamic simulations (total 540 ns) to assess their solvation profile and their thermal stability. The Reteplase-fibrin interaction was investigated by docking. The best variant was expressed in E. coli, and Box-Behnken design was used through response surface methodology to optimize its expression conditions. M72R mutant demonstrated appropriate stability, enhanced enzymatic activity (p < 0.05), and strengthened binding to fibrin, compared to the wild type. The optimal conditions for the variant's production in a bioreactor was shown to be 37 ºC, induction with 0.5 mM IPTG, for 2 h of incubation. Under these conditions, the final amount of the produced enzyme was increased by about 23 mg/L compared to the wild type, with an increase in the enzymatic activity by about 2 IU/mL. This study thus offered a new Reteplase variant with nearly all favorable properties, except solubility. The impact of temperature and incubation time on its large-scale production were underlined as well.

Production of l-Methionine from 3-Methylthiopropionaldehyde and O-Acetylhomoserine by Catalysis of the Yeast O-Acetylhomoserine Sulfhydrylase

l-Methionine is an essential bioactive amino acid with high commercial value for diverse applications. Sustained attentions have been paid to efficient and economical preparation of l-methionine. In this work, a novel method for l-methionine production was established using O-acetyl-homoserine (OAH) and 3-methylthiopropionaldehyde (MMP) as substrates by catalysis of the yeast OAH sulfhydrylase MET17. The OAH sulfhydrylase gene Met17 was cloned from Saccharomyces cerevisiae S288c and overexpressed in Escherichia coli BL21. A 49 kDa MET17 was detected in the supernatant of the recombinant E. coli strain BL21-Met17 lysate with IPTG induction, which exhibited the biological activity of l-methionine biosynthesis from OAH and MMP. The recombinant MET17 was then purified from E. coli BL21-Met17 and used for in vitro biosynthesis of l-methionine. The maximal conversion rate (86%) of OAH to l-methionine catalyzed by purified MET17 was achieved by optimization of the molar ratio of OAH to MMP. The method proposed in this study provides a possible novel route for the industrial production of l-methionine.

Expression and in vitro anticancer activity of Lp16-PSP, a member of the YjgF/YER057c/UK114 protein family from the mushroom Lentinula edodes C91-3

Latcripin-16 (Lp16-PSP) is a gene that was extracted as a result of de novo characterization of the Lentinula edodes strain C_91-3 transcriptome. The aim of the present study was to clone, express, and investigate the selective in vitro anticancer potential of Lp16-PSP in human cell lines. Lp16-PSP was analyzed using bioinformatics tools, cloned in a prokaryotic expression vector pET32a (+) and transformed into E. coli Rosetta gami. It was expressed and solubilized under optimized conditions. The differential scanning fluorometry (DSF)-guided refolding method was used with modifications to identify the proper refolding conditions for the Lp16-PSP protein. To determine the selective anticancer potential of Lp16-PSP, a panel of human cancerous and non-cancerous cell lines was used. Lp16-PSP protein was identified as endoribonuclease L-PSP protein and a member of the highly conserved YjgF/YER057c/UK114 protein superfamily. Lp16-PSP was expressed under optimized conditions (37 °C for 4 h following induction with 0.5 mM isopropyl β-D-1-thiogalactopyranoside). Solubilization was achieved with mild solubilization buffer containing 2 M urea using the freeze-thaw method. The DSF guided refolding method identified the proper refolding conditions (50 mM Tris-HCl, 100 mM NaCl, 1 mM EDTA, 400 mM Arginine, 0.2 mM GSH and 2 mM GSSG; pH 8.0) for Lp16-PSP, with a melting transition of ~ 58 °C. A final yield of ~ 16 mg of purified Lp16-PSP from 1 L of culture was obtained following dialysis and concentration by PEG 20,000. A Cell Counting Kit-8 assay revealed the selective cytotoxic effect of Lp16-PSP. The HL-60 cell line was demonstrated to be most sensitive to Lp16-PSP, with an IC₅₀ value of 74.4 ± 1.07 µg/ml. The results of the present study suggest that Lp16-PSP may serve as a potential anticancer agent; however, further investigation is required to characterize this anticancer effect and to elucidate the molecular mechanism underlying the action of Lp16-PSP.

Soluble expression, purification, and secondary structure determination of human MESP1 transcription factor

Transcription factor MESP1 is a crucial factor regulating cardiac, hematopoietic, and skeletal myogenic development. Besides, it also contributes to the generation of functional cardiomyocytes. Here, we report the soluble expression and purification of the full-length human MESP1 protein from the heterologous system, which can be delivered into the target mammalian cells. To generate this biological macromolecule, we cloned its codon-optimized gene sequence fused to a nuclear localization sequence, a cell-penetrating peptide, and a His-tag into the protein expression vector and expressed in the bacterial system (E. coli strain BL21(DE3)). Subsequently, we have screened and identified the optimal expression parameters to obtain this recombinant fusion protein in soluble form from E. coli and examined its expression concerning the placement of fusion tags at either terminal. Further, we have purified this recombinant fusion protein to homogeneity under native conditions. Notably, this purified fusion protein has maintained its secondary structure after purification, primarily comprising α-helices and random coils. This molecular tool can potentially replace its genetic and viral forms in the cardiac reprogramming of fibroblasts to induce a cardiac transcriptional profile in an integration-free manner and elucidating its role in various biological processes and diseases. KEY POINTS: • Screening of the suitable gene construct was performed and identified. • Screening of optimal expression conditions was performed and identified. • Native purification of recombinant human MESP1 protein from E. coli was performed. • Recombinant MESP1 protein has retained its secondary structure after purification.

Optimization of Culture Conditions for the Efficient Biosynthesis of Trilobatin from Phloretin by Engineered Escherichia coli Harboring the Apple Phloretin-4'-O-glycosyltransferase

Trilobatin, a dihydrochalcone glucoside and natural sweetener, has diverse biological and therapeutic properties. In the present study, we developed a microbial system to produce trilobatin from phloretin using Escherichia coli (E. coli) overexpressing the phloretin-4'-O-glycosyltransferase from Malus x domestica Borkh. Various optimization strategies were employed for the efficient production of trilobatin using a one-factor-at-a-time method. The effect of UDP-glucose supplementation, substrate, and inducer concentrations, time of substrate feeding as well as protein induction, and different culture media combinations were evaluated and optimized to enhance the production of trilobatin. As a result, the highest trilobatin production, 246.83 μM (107.64 mg L-1), was obtained with an LB-TB medium combination, 22 h of induction with 0.1 mM IPTG followed by 4 h of feeding with 250 μM phloretin and without extracellular UDP-glucose supplementation. These results demonstrate the efficient production of trilobatin and constitute a promising foundation for large-scale production of the dihydrochalcone glycosides in engineered E. coli.

Heterologous expression, purification, and refolding of SRY protein: role of L-arginine as analyzed by simulation and practical study

Escherichia coli is a widely-used cell factory for recombinant protein production, nevertheless, high amount of produced protein is seen in aggregated form. The purpose of this study was to improve the solubility of recombinant bovine sex-determining region Y protein (rbSRY) by exploring the effect of temperature, inducer, and water-arginine mixed solvent. Codon-optimized rbSRY expressed in Rosetta-gami B (DE3) pLysS and purified by NI-NTA His-select affinity chromatography in the native and denaturing conditions. A three-dimensional model of SRY was built and studied through molecular dynamics simulations in water and in the presence of L-arginine as co-solvent. Results indicated the significant effects of temperature and IPTG concentration (P < 0.001) on the solubility of rbSRY. The binding activity of native, inclusion bodies and refolded fractions to anti-rbSRY monoclonal antibody were concentration-dependent (P < 0.001). Based on molecular modeling results, the propensity of fragments in the N-terminal domain to form β-sheet and the relative instability of α-helices in terminal domains are the probable reasons for the high aggregation potential of SRY, which are mitigated in the presence of L-arginine. Altogether, our rbSRY protein was properly produced and applying appropriate culture conditions could help enhance its solubility, refold inclusion bodies, and improve its activity upon refolding.

Production and Expression Optimization of Heterologous Serratiopeptidase

BACKGROUND

Serratiopeptidase is a bacterial metalloprotease, which is useful for the treatment of pain and inflammation. It breaks down fibrin, thins the fluids formed during inflammation and acts as an anti-biofilm agent. Because of medicinally important role of the enzyme, we aimed to study the cloning and the expression optimization of serratiopeptidase.

METHODS

The heat-stable serratiopeptidase (5d7w) was selected as the template. Cloning into pET28a expression vector was performed and confirmed by colony PCR and double restriction enzyme digestion. The recombinant protein was expressed in Esherichia coli BL21 and confirmed by SDS-PAGE and Western blot analysis. Different parameters such as expression vector, culture media, post-induction incubation temperature, inducer concentration, and post-induction incubation time were altered to obtain the highest amount of the recombinant protein.

RESULTS

Serratiopeptidase was successfully cloned and expressed under optimized conditions in E. coli which confirmed by western blot analysis. The optimal conditions of expression were determined using pQE30 as vector, cultivating the host bacteria in Terrific Broth (TB) medium, at 37° C, induction by IPTG concentration equal to 0.5 mM, and cells were harvested 4 h after induction.

CONCLUSION

As serratiopeptidase is a multi-potent enzyme, the expressed recombinant protein can be considered as a valuable agent for pharmaceutical applications in further studies.

Use of plasmids for expression of proteins from the genus Leishmania in Escherichia coli: current state and perspectives

Leishmaniosis is caused by the protozoa of the genus Leishmania with a wide spectrum of clinical and epidemiological manifestations which are characterized into four clinical groups: cutaneous, mucocutaneous, diffuse cutaneous, and visceral. American visceral leishmaniosis (AVL) or visceral leishmaniosis (VL) has been known as the most severe form of the disease. However, despite the growing number of people exposed to the infection risk and the great effort done by the scientific community worldwide to significantly increase the knowledge about these diseases, there is no vaccine capable of preventing VL in humans. In this short review, we present some of the plasmids used for the expression of recombinant protein by Escherichia coli strains used mainly for the second generation of vaccines for leishmaniosis. It can be emphasized that currently, these vectors and hosts play an important role in developing vaccine strategies against the disease. Indeed, use of the E. coli BL21 (DE) strain is remarkable mainly due to its characteristics for being a stable protein producer as well as the use of histidine tags for antigen purification. KEY POINTS: • Plasmid vectors and E. coli will continue being important for studies about leishmaniosis. • Protein purification exploiting histidine tags is a key technique.

Evaluation of induction conditions for plasmid pQE-30 stability and 503 antigen of Leishmania i. chagasi expression in E. coli M15

The present study aimed to evaluate the influence of induction conditions (IPTG concentration, temperature, and induction time) on the plasmid pQE-30 stability and 503 antigen expression of Leishmania i. chagasi in Escherichia coli M15. Batch cultures were performed at 37 °C and induced by the addition of different IPTG concentrations (0.01 to 1.5 mM). Subsequently, experiments were carried out at different temperatures (27 to 42 °C), evaluating the influence of induction time (0.5 to 6 h after the start of the culture). The results showed that IPTG toxicity caused a metabolic stress in the cells and, consequently, the microorganism growth reduced. The induction with IPTG may also be associated with the plasmid pQE-30 instability, due to metabolic burden imposed by the recombinant protein expression. The optimal conditions for 503 antigen expression of Leishmania i. chagasi in Escherichia coli M15 were an IPTG concentration of 1.0 mM, temperature of 37 °C, and induction time of 2 h. The maximum antigen concentration obtained was 0.119 ± 0.009 g/L, about seven times higher than the lowest concentration. Therefore, the results showed that 503 antigen can be produced in laboratory; however, it requires more studies to minimize the plasmid instability and improve to industrial scale.

Functional characterization of host toxic EcdB transcription factor protein of echinocandin B biosynthetic gene cluster

The ecdB is a transcription factor, located in the echinocandin B biosynthetic gene cluster of Emericella rugulosa NRRL11440. Here, we validated the ecdB mRNA sequence for functional expression and to explore the role of EcdB protein in the echinocandin B regulation. The sequence alignment study revealed that the ecdB coding sequence was found 75 bp shorter than the reference mRNA sequence. This coding sequence encodes for EcdB protein and comprises three conserved domains; DNA binding domain (DBD), coiled-coil domain, and signature middle homology region. The full-length and DBD (truncated) DNA sequences were expressed in Escherichia coli BL21(DE3) under different tested conditions. The expression of EcdB protein was found to be toxic, which curbs the cell growth. In contrast to truncated protein (GST:EcdB1-54), the full-length (GST:EcdB) protein was expressed at very low titer and not detectable in SDS-PAGE under the varying isopropyl β-d-1-thiogalactopyranoside (IPTG), temperature, and media conditions. However, GST:EcdB1-54 was successfully purified under standard conditions (0.5 mM IPTG at 0.5OD) with 33 kDa expected size. The functionality of GST:EcdB1-54 was attained by electrophoretic mobility shift assay study as a clear band shifting showed with ecdA promoter. Taken together, we conclude that EcdB interacts with the ecdA promoter that reflected to require for echinocandin B regulation.

The Goldilocks Approach: A Review of Employing Design of Experiments in Prokaryotic Recombinant Protein Production

The production of high yields of soluble recombinant protein is one of the main objectives of protein biotechnology. Several factors, such as expression system, vector, host, media composition and induction conditions can influence recombinant protein yield. Identifying the most important factors for optimum protein expression may involve significant investment of time and considerable cost. To address this problem, statistical models such as Design of Experiments (DoE) have been used to optimise recombinant protein production. This review examines the application of DoE in the production of recombinant proteins in prokaryotic expression systems with specific emphasis on media composition and culture conditions. The review examines the most commonly used DoE screening and optimisation designs. It provides examples of DoE applied to optimisation of media and culture conditions.

Redox control and autoxidation of class 1, 2 and 3 phytoglobins from Arabidopsis thaliana

Despite a recent increase in interest towards phytoglobins and their importance in plants, much is still unknown regarding their biochemical/biophysical properties and physiological roles. The present study presents data on three recombinant Arabidopsis phytoglobins in terms of their UV-vis and Raman spectroscopic characteristics, redox state control, redox potentials and autoxidation rates. The latter are strongly influenced by pH for all three hemoglobins - (with a fundamental involvement of the distal histidine), as well as by added anion concentrations - suggesting either a process dominated by nucleophilic displacement of superoxide for AtHb2 or an inhibitory effect for AtHb1 and AtHb3. Reducing agents, such as ascorbate and glutathione, are found to either enhance- (presumably via direct electron transfer or via allosteric regulation) or prevent autoxidation. HbFe3+ reduction was possible in the presence of high (presumably not physiologically relevant) concentrations of NADH, glutathione and ascorbate, with differing behaviors for the three globins. The iron coordination sphere is found to affect the autoxidation, redox state interconversion and redox potentials in these three phytoglobins.

Expression and purification of biologically active recombinant rabbit monocyte chemoattractant protein1 in Escherichia coli

Monocyte chemoattractant protein 1 (MCP1) with recruiting monocytes is an important factor at the beginning of inflammatory disorders such as atherosclerosis which seems its blocking preclude this process and help improvement of related diseases. To perform clinical research in this field, MCP1 protein is required but firstly, animal studies should be done. As the rabbit is a suitable model for many inflammatory disorders, and Escherichia coli BL21(DE3) (BL21) cell is a high-efficiency host for protein expression, we decided to produce recombinant rabbit MCP1 (rRMCP1) in BL21/pET28a system. After codon usage, a construct containing RMCP1 sequence was synthesized, cloned into the pET28a plasmid, and overexpressed in BL21 cells. Followed that, with changing expression condition such as cell concentration before the induction, time period, temperature, shaking rate and inducer concentration (IPTG), rRMCP1 expression was optimized, and purified by Ni-NTA. The biological activity of the expressed protein was verified using monocyte migration assay. Using this expression system, nearly 28 mg/mL rRMCP1 was produced at 26°C/180 rpm for 24 h in LB broth medium with 1 mM IPTG. Therefore, we were succeeded to express the intermediate level of rRMCP1 with this method. This amount of protein is sufficient for biological researches in the laboratory.

Optimization of culturing conditions of recombined Escherichia coli to produce umami octopeptide-containing protein

Using synthesized peptides to verify the taste of natural peptides was probably the leading cause for tasting disputes regarding umami peptides. A novel method was developed to prepare the natural peptide which could be used to verify the taste of umami peptide. A controversial octopeptide was selected and gene engineering was used to structure its Escherichia coli. expressing vector. A response surface method was adopted to optimize the expression conditions of the recombinant protein. The results of SDS-PAGE for the recombinant protein indicated that the recombinant expression system was successfully structured. The fitting results of the response surface experiment showed that the OD₆₀₀ value was the key factor which influenced the expression of the recombinant protein. The optimal culturing process conditions predicted with the fitting model were an OD₆₀₀ value of 0.5, an IPTG concentration of 0.6mM, a culturing temperature of 28.75°C and a culturing time of 5h.