Production of a cytotoxic cationic antibacterial peptide in Escherichia coli using SUMO fusion partner

Extracellular production of Ulp1403-621 in leaky E. coli and its application in antimicrobial peptide production

Small ubiquitin-like modifier (SUMO) tag is widely used to promote soluble expression of exogenous proteins, which can then be cleaved by ubiquitin-like protease 1 (Ulp1) to obtain interested protein. But the application of Ulp1 in large-scale recombinant protein production is limited by complicated purification procedures and high cost. In this study, we describe an efficient and simple method of extracellular production of Ulp1_403-621 using a leaky Escherichia coli BL21(DE3), engineered by deleting the peptidoglycan-associated outer membrane lipoprotein (pal) gene. Ulp1_403-621 was successfully leaked into extracellular supernatant by the BL21(DE3)-Δpal strain after IPTG induction. The addition of 1% glycine increased the extracellular production of Ulp1_403-621 approximately four fold. Moreover, extracellular Ulp1_403-621 without purification had high activities for cleaving SUMO fusion proteins, and antimicrobial peptide pBD2 obtained after cleavage can inhibit the growth of Staphylococcus aureus. The specific activity of extracellular Ulp1_403-621 containing 1 mM EDTA and 8 mM DTT reached 2.0 × 10⁶ U/L. Another commonly used protease, human rhinovirus 3C protease, was also successfully secreted by leaky E. coli strains. In conclusion, extracellular production of tool enzymes is an attractive way for producing large-scale active recombinant proteins at a lower cost for pharmaceutical, industrial, and biotechnological applications. KEY POINTS: • First report of extracellular production of Ulp1_403-621 in leaky Escherichia coli BL21(DE3) strain. • One percent glycine addition into cultivation medium increased the extracellular production of Ulp1_403-621 approximately four fold. • The specific activity of extracellular Ulp1_403-621 produced in this study reached 2.0 × 10⁶ U/L.

Strategies for improving antimicrobial peptide production

Antimicrobial peptides (AMPs) found in a wide range of animal, insect, and plant species are host defense peptides forming an integral part of their innate immunity. Although the exact mode of action of some AMPs is yet to be deciphered, many exhibit membrane lytic activity or interact with intracellular targets. The ever-growing threat of antibiotic resistance has brought attention to research on AMPs to enhance their clinical use as a therapeutic alternative. AMPs have several advantages over antibiotics such as broad range of antimicrobial activities including anti-fungal, anti-viral and anti-bacterial, and have not reported to contribute to resistance development. Despite the numerous studies to develop efficient production methods for AMPs, limitations including low yield, degradation, and loss of activity persists in many recombinant approaches. In this review, we outline available approaches for AMP production and various expression systems used to achieve higher yield and quality. In addition, recent advances in recombinant strategies, suitable fusion protein partners, and other molecular engineering strategies for improved AMP production are surveyed.

A novel approach of recombinant laterosporulin production using the N-SH2 domain of SHP-2

Background

The current study was aimed at evaluating the role of the N-SH2 domain of SHP-2 as a partner protein in the expression of a toxic peptide, laterosporulin (LTS). We also investigated its effects on the formation of the disulfide bond and functional folding of the peptide in vitro. The N-SH2-LTS protein was expressed as a His-tagged fusion protein, capable of undergoing enzymatic cleavage.

Results

Based on the data presented herein, the total yield of the folded fusion protein from inclusion bodies was found to be about 105 mg/l, demonstrating a high-level of heterologous expression. After enzymatic cleavage, 1.5 mg of the folded recombinant laterosporulin was obtained from each 10 mg of the fusion protein. The purity of the recombinant laterosporulin was analyzed by RP-HPLC, to yield peptides with suitable purity (85%).

Conclusions

Our findings indicated the advantages of using the N-SH2 domain of SHP-2 as a rapid and easy approach not only in producing easy target proteins but also in its function as a chaperone. N-SH2 domain of SHP-2 can influence on the purification of laterosporulin at reasonable yield and in a cost-effective fashion. The N-SH2 domain of SHP-2 as a protein chaperone may be potentially favorable to produce other proteins with disulfide bonds.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12896-021-00721-7.

Covalent binding of glutathione on magnetic nanoparticles: Application for immobilizing small fragment ubiquitin-like-specific protease 1

Magnetic nanoparticles bound with glutathione (GSH) are useful for diagnostics, enzyme immobilization, and affinity precipitation by using the strong and specific interaction of GSH with glutathione S-transferase (GST)-fused proteins. Our studies revealed that GSH-bound magnetic nanoparticles could be obtained using the covalent bond linkage of GSH and nanoparticles to promote the stability of bound GSH. To yield this conjugate, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared and modified using tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES), which introduced amino groups that were then activated with maleic anhydride (MA) for covalent binding of GSH. After MA was used to activate the amino-grafted SPION for 24 h, the yield of GSH conjugation increased over 4 days from 37 % to 74 % of the original amine density on the surface as the incubation of GSH with MA-activated SPION. These GSH-bound magnetic nanoparticles, designated as SPION@silica-GSH with approximately 103 nmol GSH/mg particles, were ready for coupling with GST-fused protein through the GSH-GST affinity interaction. A GST-tagged small fragment of ubiquitin-like-specific protease 1 (sfULP1) was used as the model protein for immobilization on SPION@silica-GSH. ULP1 is a small ubiquitin-like modifier (SUMO) protease. Results indicated that this immobilized GST-sfULP1 could retain 87 % ± 5 % enzyme activity of free protease before immobilization and could catalyze the cleavage of the SUMO-fused peptide (SUMO-GLP-1) to obtain glucagon-like peptide-1, a peptide hormone for type 2 diabetes therapy.

Antimicrobial activity and mechanism of peptide CM4 against Pseudomonas aeruginosa

Antibacterial peptide CM4 (ABP-CM4) is a small cationic peptide with broad-spectrum activities against bacteria, fungi and tumor cells and may possibly be used as an antimicrobial agent. In this study, a C-terminal amidated antibacterial peptide ABP-CM4 (ABP-CM4N) with the strongest antibacterial activity was obtained through screening the antibacterial activities of ABP-CM4 with different modifications. The minimal inhibitory concentration of ABP-CM4N was 8 μM against P. aeruginosa (ATCC 27853) which was lower than that of ABP-CM4 (16 μM). The strengthened antimicrobial activity of ABP-CM4N may be associated with the increased membrane binding capacity, being two times that of ABP-CM4 (p < 0.001). The antibacterial mechanism of ABP-CM4N to Pseudomonas aeruginosa was examined by means of cell membrane integrity analysiss, the intracellular ultrastructure change observation and E. coli genomic DNA binding assay. It was found that ABP-CM4N had the same antimicrobial mechanism as ABP-CM4, and the aim of the antimicrobial mechanism was mainly to destroy the cell membrane which caused nucleic acid or protein leakage, and secondly to interact with E. coli genomic DNA after penetrating the cell membrane. Furthermore, in vitro ABP-CM4N showed a better bacteriostatic activity in meats, with the treated samples showing two to three times less positive colonies than ABP-CM4.

Making plants into cost-effective bioreactors for highly active antimicrobial peptides

As antibiotic-resistant bacterial pathogens become an ever-increasing concern, antimicrobial peptides (AMPs) have grown increasingly attractive as alternatives. Potentially, plants could be used as cost-effective AMP bioreactors; however, reported heterologous AMP expression is much lower in plants than in E. coli expression systems and often results in plant cytotoxicity, even for AMPs fused to carrier proteins. This suggests that there may be a physical characteristic of the previously described heterologous AMPs which impedes efficient expression in plants. Using a meta-analysis of protein databases, this study has determined that native plant AMPs were significantly less cationic than AMPs native to other taxa. To apply this finding to plant expression, the transient expression of 10 different heterologous AMPs, ranging in charge from +7 to -5, was tested in the tobacco, Nicotiana benthamiana. Elastin-like polypeptide (ELP) was used as the carrier protein for AMP expression. ELP fusion allowed for a simple, cost-effective temperature shift purification. Using this system, all five anionic AMPs expressed well, with two at unusually high levels (375 and 563 μg/gfw). Furthermore, antimicrobial activity against Staphylococcus epidermidis was an order of magnitude greater (average minimum inhibitory concentration MIC of 0.26μM) than that typically seen for AMPs expressed in E. coli systems and was associated with the uncleaved fusion peptide. In summary, this study describes a means of expressing AMP fusions in plants in high yield, purified by a simple temperature-shift protocol, resulting in a fusion peptide with high antimicrobial activity and without the need for a peptide cleavage step.

High Level Expression and Purification of the Clinically Active Antimicrobial Peptide P-113 in Escherichia coli

P-113, which was originally derived from the human saliva protein histatin 5, is a histidine-rich antimicrobial peptide with the sequence AKRHHGYKRKFH. P-113 is currently undergoing phase II clinical trial as a pharmaceutical agent to fight against fungal infections in HIV patients with oral candidiasis. Previously, we developed a new procedure for the high-yield expression and purification of hG31P, an analogue and antagonist of human CXCL8. Moreover, we have successfully removed lipopolysaccharide (LPS, endotoxin) associated with hG31P in the expression with Escherichia coli. In this paper, we have used hG31P as a novel fusion protein for the expression and purification of P-113. The purity of the expressed P-113 is more than 95% and the yield is 4 mg P-113 per liter of E. coli cell culture in Luria-Bertani (LB) medium. The antimicrobial activity of the purified P-113 was tested. Furthermore, we used circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy to study the structural properties of P-113. Our results indicate that using hG31P as a fusion protein to obtain large quantities of P-113 is feasible and is easy to scale up for commercial production. An effective way of producing enough P-113 for future clinical studies is evident in this study.

Optimization of the Expression of DT386-BR2 Fusion Protein in Escherichia coli using Response Surface Methodology

Background:

The aim of this study was to determine the best condition for the production of DT386-BR2 fusion protein, an immunotoxin consisting of catalytic and translocation domains of diphtheria toxin fused to BR2, a cancer specific cell penetrating peptide, for targeted eradication of cancer cells, in terms of the host, cultivation condition, and culture medium.

Materials and Methods:

Recombinant pET28a vector containing the codons optimized for the expression of the DT386-BR2 gene was transformed to different strains of Escherichia coli (E. coli BL21 DE3, E. coli Rosetta DE3 and E. coli Rosetta-gami 2 DE3), followed by the induction of expression using 1 mM IPTG. Then, the strain with the highest ability to produce recombinant protein was selected and used to determine the best expression condition using response surface methodology (RSM). Finally, the best culture medium was selected.

Results:

Densitometry analysis of sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the expressed fusion protein showed that E. coli Rosetta DE3 produced the highest amounts of the recombinant fusion protein when quantified by 1 mg/ml bovine serum albumin (178.07 μg/ml). Results of RSM also showed the best condition for the production of the recombinant fusion protein was induction with 1 mM IPTG for 2 h at 37°C. Finally, it was established that terrific broth could produce higher amounts of the fusion protein when compared to other culture media.

Conclusion:

In this study, we expressed the recombinant DT386-BR2 fusion protein in large amounts by optimizing the expression host, cultivation condition, and culture medium. This fusion protein will be subjected to purification and evaluation of its cytotoxic effects in future studies.

Identification of a cyclodextrin inclusion complex of antimicrobial peptide CM4 and its antimicrobial activity

Antibacterial peptide CM4 (ABP-CM4) is a natural product isolated from the silkworm Bombyx mori. It is a small cationic peptide with broad-spectrum activities against harmful microorganisms and may be used as a novel food preservative. However, ABP-CM4 lacks tertiary structure in water-like solutions, which makes it more susceptible to proteases and labile when exposed to air. In this study, β-cyclodextrin (β-CD) was chosen to form an inclusion complex with ABP-CM4, which enhanced the physical and chemical properties of ABP-CM4 but did not decrease its antibacterial activity. The storage stability and susceptibility to proteinases of ABP-CM4 were apparently improved under the protection of β-CD. This technology could also be widely applied to other AMPs as an antimicrobial system to be used in the food industry.

High Efficient Expression, Purification, and Functional Characterization of Native Human Epidermal Growth Factor in Escherichia coli

Human epidermal growth factor (hEGF) is a small, mitotic growth polypeptide that promotes the proliferation of various cells and is widely applied in clinical practices. However, high efficient expression of native hEGF in Escherichia coli has not been successful, since three disulfide bonds in monomer hEGF made it unable to fold into correct 3D structure using in vivo system. To tackle this problem, we fused Mxe GyrA intein (Mxe) at the C-terminal of hEGF followed by small ubiquitin-related modifier (SUMO) and 10x His-tag to construct a chimeric protein hEGF-Mxe-SUMO-H10. The fusion protein was highly expressed at the concentration of 281 mg/L and up to 59.5% of the total cellular soluble proteins. The fusion protein was purified by affinity chromatography and 29.4 mg/L of native hEGF can be released by thiol induced N-terminal cleavage without any proteases. The mitotic activity in Balb/c 3T3 cells is proliferated by commercial and recombinant hEGF measured with methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay which indicated that recombinant hEGF protein stimulates the cell proliferation similar to commercial protein. This study significantly improved the yield and reduced the cost of hEGF in the recombinant E. coli system and could be a better strategy to produce native hEGF for pharmaceutical development.

Design, characterization and expression of a novel hybrid peptides melittin (1-13)-LL37 (17-30)

Hybridizing of different antimicrobial peptides (AMPs) has been a common practice for obtaining novel hybrid AMPs with elevated antibacterial activity but minimized cytotoxicity. The hybrid peptides melittin (1-13)-LL37 (17-30) (M-L) combining the hydrophobic N-terminal fragment of melittin (M) with the core antibacterial fragment of LL37 (L), was designed for the first time to explore its antibacterial activity and hemolytic activity against bacteria and sheep erythrocyte respectively. Results showed that M-L had an even more potent antibacterial activity against all indicator strains (especially gram-positive bacteria) than M and L, whereas didn't exhibit hemolytic activity to sheep erythrocytes, implying M-L can be served as a potential therapeutic drug to substitute traditional antibiotics. However the high expense of biosynthesis limited its further research, therefore fusion expression of M-L was carried out in Escherichia coli (E. coli) for overproducing the hybrid peptide so as to solve the problem. The DNA sequence encoding M-L with preferred codons was cloned into the pET-SUMO vector for protein expression in E. coli BL21 (DE3). After IPTG induction, approximately 165 mg soluble fusion protein SUMO-M-L was recovered per liter supernatant of the fermentation ultrasonic lysate using Ni-NTA Sepharose column (92 % purity). And 23 mg recombinant M-L was obtained per liter culture after cleavage of SUMO protease and purification of Ni-NTA Sepharose column. In sum, this research not only supplied an effective approach for overproducing hybrid peptide M-L, but paved the way for its further exploration on pharmaceutical potential and medical importance.

Recombinant production of the antimicrobial peptide NZ17074 in Pichia pastoris using SUMO3 as a fusion partner

The antimicrobial peptide NZ17074, which is derived from arenicin-3 isolated from Arenicola marina, displayed high activity against a broad range of pathogenic bacteria and fungi. However, NZ17074 has not been produced using fermentation technology. The aim of this work was to study the expression of difficult-to-express NZ17074 in Pichia pastoris by fusing with SUMO3. The DNA fragments of NZ17074 and SUMO3 were fused into SUMO3-NZ17074 using overlap PCR and cloned into the pPICZαA vector to construct the pPICZ-SUMO3-NZ17074 expression vector. The rSUMO3-NZ17074 fusion protein, purified by Ni(2) (+) -chelating affinity chromatography, was cleaved by 50% formic acid at 50°C for 28 h to release recombinant NZ17074 (rNZ17074). After purification with second affinity column, 4·1 mg rNZ17074 peptide with the purity over 90% was obtained from per litre fermentation culture. The rNZ17074 peptide exhibited the significant inhibition activity against Gram-negative bacteria: its minimal inhibitory concentrations (MICs) against Escherichia coli, Salmonella enteritidis and Pseudomonas aeruginosa were 2-4, 2 and 8-16 μg ml(-1) , respectively, which indicated that SUMO3 is a good fusion partner for the expression of the toxic peptide.

SIGNIFICANCE AND IMPACT OF THE STUDY

Recombinant active NZ17074 was produced with Pichia pastoris by using high-density fermentation technology for the first time. Our findings demonstrated the usefulness of SUMO-fusion technology as an effective expression strategy for synthesizing peptides in yeast. This SUMO3 expression system with a lower cost would likely be widely used for the production of other cytotoxic proteins including antimicrobial peptides.

Recombinant expression of antimicrobial peptides using a novel self-cleaving aggregation tag in Escherichia coli

Antimicrobial peptides (AMPs) are part of the innate immune system of complex multicellular organisms. Despite the fact that AMPs show great potential as a novel class of antibiotics, the lack of a cost-effective means for their mass production limits both basic research and clinical use. In this work, we describe a novel expression system for the production of antimicrobial peptides in Escherichia coli by combining ΔI-CM mini-intein with the self-assembling amphipathic peptide 18A to drive the formation of active aggregates. Two AMPs, human β-defensin 2 and LL-37, were fused to the self-cleaving tag and expressed as active protein aggregates. The active aggregates were recovered by centrifugation and the intact antimicrobial peptides were released into solution by an intein-mediated cleavage reaction in cleaving buffer (phosphate-buffered saline supplemented with 40 mmol/L Bis–Tris, 2 mmol/L EDTA, pH 6.2). The peptides were further purified by cation-exchange chromatography. Peptides yields of 0.82 ± 0.24 and 0.59 ± 0.11 mg/L were achieved for human β-defensin 2 and LL-37, respectively, with demonstrated antimicrobial activity. Using our expression system, intact antimicrobial peptides were recovered by simple centrifugation from active protein aggregates after the intein-mediated cleavage reaction. Thus, we provide an economical and efficient way to produce intact antimicrobial peptides in E. coli.

To fuse or not to fuse: what is your purpose?

Since the dawn of time, or at least the dawn of recombinant DNA technology (which for many of today's scientists is the same thing), investigators have been cloning and expressing heterologous proteins in a variety of different cells for a variety of different reasons. These range from cell biological studies looking at protein-protein interactions, post-translational modifications, and regulation, to laboratory-scale production in support of biochemical, biophysical, and structural studies, to large scale production of potential biotherapeutics. In parallel, fusion-tag technology has grown-up to facilitate microscale purification (pull-downs), protein visualization (epitope tags), enhanced expression and solubility (protein partners, e.g., GST, MBP, TRX, and SUMO), and generic purification (e.g., His-tags, streptag, and FLAG™-tag). Frequently, these latter two goals are combined in a single fusion partner. In this review, we examine the most commonly used fusion methodologies from the perspective of the ultimate use of the tagged protein. That is, what are the most commonly used fusion partners for pull-downs, for structural studies, for production of active proteins, or for large-scale purification? What are the advantages and limitations of each? This review is not meant to be exhaustive and the approach undoubtedly reflects the experiences and interests of the authors. For the sake of brevity, we have largely ignored epitope tags although they receive wide use in cell biology for immunopreciptation.

Secretory expression of lacticin Q fused with SUMO in Bacillus subtilis

Lacticin Q is a 53-amino acid Class II bacteriocin produced by Lactococcus lactis QU 5. It shows antibacterial activity comparable to that of nisin A in terms of both spectrum and intensity. Moreover, it remains stable at alkaline pH values, while nisin A was inactivated. It may possibly be employed as an alternative to or in combination with nisin A. The objective of this study was to express lacticin Q extracellularly with Small ubiquitin-related modifier (SUMO) fusion technology in Bacillus subtilis. Secretory SUMO-lacticin Q fusion protein was efficiently produced in B. subtilis WB600 transformed with the recombinant expression plasmid and accounted for 19% of the culture supernatant proteins. Fusion SUMO-lacticin Q was purified by nickel nitrilotriacetate (Ni-NTA) affinity chromatography and digested with SUMO protease to release lacticin Q. Lacticin Q was further purified by Ni-NTA chromatography to yield about 2.5 mg of lacticin Q with more than 93% purity from 1L of supernatant of fermentation culture. An activity assay indicated that the recombinant bacteriocin exhibited excellent antimicrobial activity against indicator strains. The results obtained suggest that the secretory lacticin Q was efficiently expressed using SUMO fusion technology in B. subtilis. The expression and purification system could promote the application of lacticin Q in food and medicine.

Expression systems for heterologous production of antimicrobial peptides

Antimicrobial peptides (AMPs) consist of molecules that act on the defense systems of numerous organisms toward multiple pathogens such as bacteria, fungi, parasites and viruses. These compounds have become extremely significant due to the increasing resistance of microorganisms to common antibiotics. However, the low quantity of peptides obtained from direct purification is, to date, still a remarkable bottleneck for scientific and industrial research development. Therefore, this review describes the main heterologous systems currently used for AMP production, including bacteria, fungi and plants, and also the related strategies for reaching greater functional peptide production. The main difficulties of each system are also described in order to provide some directions for AMP production. In summary, data revised here indicate that large-scale production of AMPs can be obtained using biotechnological tools, and the products may be applied in the pharmaceutical industry as well as in agribusiness.

Molecular cloning, functional characterization and phylogenetic analysis of TRAIL in Japanese pufferfish Takifugu rubripes

In this study, the complementary DNA (cDNA) of Japanese pufferfish Takifugu rubripes tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) was cloned by reverse-transcription PCR. The open reading frame of the TRAIL consisted of 870 bases. The deduced amino-acid sequence of the TRAIL showed a high homology with the sequences of other teleosts. Recombinant soluble TRAIL was fused with a small ubiquitin-related modifier gene to enhance the soluble expression level in Escherichia coli BL21 (DE3). In vitro, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide (MTT) assay indicated that the purified soluble TRAIL was able to induce apoptosis of Jurkat and HeLa cells in a dose-dependent manner.

Multifunctional cationic host defence peptides and their clinical applications

With the rapid rise in the emergence of bacterial strains resistant to multiple classes of antimicrobial agents, there is an urgent need to develop novel antimicrobial therapies to combat these pathogens. Cationic host defence peptides (HDPs) and synthetic derivatives termed innate defence regulators (IDRs) represent a promising alternative approach in the treatment of microbial-related diseases. Cationic HDPs (also termed antimicrobial peptides) have emerged from their origins as nature's antibiotics and are widely distributed in organisms from insects to plants to mammals and non-mammalian vertebrates. Although their original and primary function was proposed to be direct antimicrobial activity against bacteria, fungi, parasites and/or viruses, cationic HDPs are becoming increasingly recognized as multifunctional mediators, with both antimicrobial activity and diverse immunomodulatory properties. Here we provide an overview of the antimicrobial and immunomodulatory activities of cationic HDPs, and discuss their potential application as beneficial therapeutics in overcoming infectious diseases.

Expression of linear permutated variants from circular enterocin AS-48

To confirm whether the head-to-tail circularization could be involved in the stability and activity of the circular bacteriocin AS-48, two permutated linear structural as-48A genes have been constructed by circular permutation. The absence of the leaderless linear AS(23/24) and AS(48/49) proteins in Escherichia coli, under all the conditions investigated, supports the idea that the circular backbone is important to stabilize their structure and also indicates the significance of a leader peptide. In fact, the approach taken in this study to generate linear permutated proteins fused to an appropriate partner was sufficient to prevent cellular proteolysis. In this case, the high expression levels found favour their intracellular accumulations as inclusion bodies, which after solubilization showed a propensity to aggregate, thus hindering the specific EK cleavage. This could explain the presence of active hybrid tagged proteins identified in this work. The conserved distribution of hydrophobic and hydrophilic surfaces in the hybrid proteins is responsible for the antibacterial activity. In addition, the opening of the AS-48 molecule between the residues G(23) W(24) connecting the α1/α2 helices, confers greater stability, suggesting that the sequence and/or the free amino acid in the polypeptide chain are critical aspects in the design of new variants.

Cost-effective expression and purification of antimicrobial and host defense peptides in Escherichia coli

Cationic antimicrobial host defense peptides (HDPs) combat infection by directly killing a wide variety of microbes, and/or modulating host immunity. HDPs have great therapeutic potential against antibiotic-resistant bacteria, viruses and even parasites, but there are substantial roadblocks to their therapeutic application. High manufacturing costs associated with amino acid precursors have limited the delivery of inexpensive therapeutics through industrial-scale chemical synthesis. Conversely, the production of peptides in bacteria by recombinant DNA technology has been impeded by the antimicrobial activity of these peptides and their susceptibility to proteolytic degradation, while subsequent purification of recombinant peptides often requires multiple steps and has not been cost-effective. Here we have developed methodologies appropriate for large-scale industrial production of HDPs; in particular, we describe (i) a method, using fusions to SUMO, for producing high yields of intact recombinant HDPs in bacteria without significant toxicity and (ii) a simplified 2-step purification method appropriate for industrial use. We have used this method to produce seven HDPs to date (IDR1, MX226, LL37, CRAMP, HHC-10, E5 and E6). Using this technology, pilot-scale fermentation (10L) was performed to produce large quantities of biologically active cationic peptides. Together, these data indicate that this new method represents a cost-effective means to enable commercial enterprises to produce HDPs in large-scale under Good Laboratory Manufacturing Practice (GMP) conditions for therapeutic application in humans.