Production of the recombinant antimicrobial peptide UBI 18-35 in Escherichia coli

Removal and monitoring of residual nucleic acids from core streptavidin inclusion bodies for increased refolding yield

Commercial production of recombinant streptavidin (SAV) using soluble expression route is cost-prohibitive, resulting from its inherent toxicity toward commercially available Escherichia coli hosts (such as BL21) and low productivity of existing manufacturing processes. Quality challenges can also result from binding of streptavidin in the host cells. One way to overcome these challenges is to allow formation of inclusion bodies (IBs). Nevertheless, carried-over cellular contaminants during IBs preparation can hinder protein refolding and application of SAV in nucleic acid-based applications. Hence, removing associated contaminants in recombinant IBs is imperative for maximum product outcomes. In this study, the IBs isolation method from our group was improved to remove residual DNA found in refolded core SAV (cSAV). The improvements were attained by incorporating quantitative real-time polymerase chain reactions (qPCR) for residual DNA monitoring. We attained 99 % cellular DNA removal from cSAV IBs via additional wash and sonication steps, and the addition of benzonase nuclease during lysis. A 10 % increment of cSAV refolding yield (72 %) and 83 % reduction of residual DNA from refolding of 1 mg cSAV IBs were observed under extensive sonication. Refolding of cSAV was not affected and its activity was not compromised. The optimized process reported here highlights the importance of obtaining cSAV IBs with minimal contaminants prior to refolding to increase product yield, and the usefulness of the qPCR method to monitor nucleic acid removed from each step of the process.

Detection strategies of infectious diseases via peptide-based electrochemical biosensors

Infectious diseases have threatened human life for as long as humankind has existed. One of the most crucial aspects of fighting against these infections is diagnosis to prevent disease spread. However, traditional diagnostic methods prove insufficient and time-consuming in the face of a pandemic. Therefore, studies focusing on detecting viruses causing these diseases have increased, with a particular emphasis on developing rapid, accurate, specific, user-friendly, and portable electrochemical biosensor systems. Peptides are used integral components in biosensor fabrication for several reasons, including various and adaptable synthesis protocols, long-term stability, and specificity. Here, we discuss peptide-based electrochemical biosensor systems that have been developed over the last decade for the detection of infectious diseases. In contrast to other reports on peptide-based biosensors, we have emphasized the following points i) the synthesis methods of peptides for biosensor applications, ii) biosensor fabrication approaches of peptide-based electrochemical biosensor systems, iii) the comparison of electrochemical biosensors with other peptide-based biosensor systems and the advantages and limitations of electrochemical biosensors, iv) the pros and cons of peptides compared to other biorecognition molecules in the detection of infectious diseases, v) different perspectives for future studies with the shortcomings of the systems developed in the past decade.

Revolutionizing orthopedic healthcare: a systematic review unveiling recombinant antimicrobial peptides

The increasing demand for orthopedic surgeries, including joint replacements, is driven by an aging population and improved diagnosis of joint conditions. Orthopedic surgeries carry a risk of infection, especially in patients with comorbidities. The rise of antibiotic resistance exacerbates this issue, necessitating alternatives like in vitro bioengineered antimicrobial peptides (AMPs), offering broad-spectrum activity and multiple action mechanisms. This review aimed to assess the prevalence of antimicrobial potential and the yield after purification among recombinant AMP families. The antimicrobial potential was evaluated using the Minimum Inhibitory Concentration (MIC) values against the most common bacteria involved in clinical infections. This systematic review adhered to PRISMA guidelines, focusing on in vitro studies of recombinant AMPs. The search strategy was run on PubMed, Scopus and Embase up to 30th March 2023. The Population, Exposure and Outcome model was used to extract the data from studies and ToxRTool for the risk of bias analysis. This review included studies providing peptide production yield data and MIC values against pathogenic bacteria. Non-English texts, reviews, conference abstracts, books, studies focusing solely on chemical synthesis, those reporting incomplete data sets, using non-standard MIC assessment methods, or presenting MIC values as ranges rather than precise concentrations, were excluded. From 370 publications, 34 studies on AMPs were analyzed. These covered 46 AMPs across 18 families, with Defensins and Hepcidins being most common. Yields varied from 0.5 to 2,700 mg/L. AMPs were tested against 23 bacterial genera, with MIC values ranging from 0.125 to >1,152 μg/mL. Arenicins showed the highest antimicrobial activity, particularly against common orthopedic infection pathogens. However, AMP production yields varied and some AMPs demonstrated limited effectiveness against certain bacterial strains. This systematic review emphasizes the critical role of bioengineered AMPs to cope infections and antibiotic resistance. It meticulously evaluates recombinant AMPs, focusing on their antimicrobial efficacy and production yields. The review highlights that, despite the variability in AMP yields and effectiveness, Arenicins and Defensins are promising candidates for future research and clinical applications in treating antibiotic-resistant orthopedic infections. This study contributes significantly to the understanding of AMPs in healthcare, underscoring their potential in addressing the growing challenge of antibiotic resistance. Systematic review registration:https://osf.io/2uq4c/.

Carrier proteins boost expression of PR-39-derived peptide in Pichia pastoris

AIMS

Multidrug resistance presents difficulties in preventing and treating bacterial infections. Proline-rich antimicrobial peptides (PrAMPs) inhibit bacterial growth by affecting the intracellular targets rather than by permeabilizing the membrane. The aim of this study was to develop a yeast-based fusion carrier system using calmodulin (CaM) and xylanase (XynCDBFV) as two carriers to express the model PrAMP PR-39-derived peptide (PR-39-DP) in Pichia pastoris.

METHODS AND RESULTS

Fusion protein secreted into the culture supernatant was purified in a one-step on-column digestion using human rhinovirus 3C protease, obtaining the target peptide PR-39-DP. The growth curves of Escherichia coli were monitored by recording the OD600 values of the bacteria. The antibacterial activity of PR-39-DP was evaluated in killing assays performed on E. coli. The yield of PR-39-DP was 1.0-1.2 mg l-1 in the CaM fusion carrier system, approximately three times that of the XynCDBFV fusion carrier system. The minimal inhibitory concentration of PR-39-DP was ∼10.5 µg ml-1.

CONCLUSIONS

CaM and XynCDBFV provide increased stability and promote the expression and secretion of active PR-39-DP.

Efficient Delivery of Antimicrobial Peptides in an Innovative, Slow-Release Pharmacological Formulation

Both nanostructure and multivalency enhance the biological activities of antimicrobial peptides (AMPs), whose mechanism of action is cooperative. In addition, the efficacy of a particular AMP should benefit from a steady concentration at the local place of action and, therefore, from a slow release after a dynamic repository. In the context of emerging multi-resistant bacterial infections and the urgent need for novel and effective antimicrobial drugs, we tested these concepts through the engineering of four AMPs into supramolecular complexes as pharmacological entities. For that purpose, GWH1, T22, Pt5, and PaD, produced as GFP or human nidogen-based His-tagged fusion proteins, were engineered as self-assembling oligomeric nanoparticles ranging from 10 to 70 nm and further packaged into nanoparticle-leaking submicron granules. Since these materials slowly release functional nanoparticles during their time-sustained unpacking, they are suitable for use as drug depots in vivo. In this context, a particular AMP version (GWH1-NIDO-H6) was selected for in vivo validation in a zebrafish model of a complex bacterial infection. The GWH1-NIDO-H6-secreting protein granules are protective in zebrafish against infection by the multi-resistant bacterium Stenotrophomonas maltophilia, proving the potential of innovative formulations based on nanostructured and slowly released recombinant AMPs in the fight against bacterial infections.

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.

Immunological detection of AcAMP antimicrobial peptide secreted by Aspergillus clavatus

Background and Objectives:

Aspergillus clavatus antimicrobial peptide (AcAMP) is a fungi-derived peptide with a broad spectrum of activity against pathogenic bacteria and fungi. Natural antimicrobial peptides, including AcAMP, have attracted many attentions in the development of new natural antibiotics against pathogenic bacteria, especially multidrug resistant ones.

Materials and Methods:

In the present study, acamp gene was codon-optimized and chemically synthesized in pUC57 cloning vector, subcloned into pET28a (+) expression vector and transferred into competent Escherichia coli BL21 (DE3) cells. The expression of AcAMP was induced by addition of Isopropyl β- d-1-thiogalactopyranoside (IPTG) and the expressed peptide was purified by Ni-NTA. BALB/c mice were immunized with the purified peptide and the ability of the immunized mice sera for the detection of the native AcAMP secreted by A. clavatus IRAN 142C was examined through ELISA and Western blotting techniques.

Results:

Both ELISA and Western blotting demonstrated the ability of the sera of the immunized mice to detect the native AcAMP.

Conclusion:

The results of the present work show that the raised antibody against recombinant AcAMP can be used to detect AcAMP peptide, an issue which paves the way to develop detection kits for the detection of AcAMP-producing organisms, purification of this valuable peptide for further investigations.

Radiolabeled Complex of Antimicrobial Peptides UBI29-41 and UBI18-35 Labeled with 99mTc for Differential Diagnosis of Bone Infection of the Limbs

We studied an original radiolabeled complex of antimicrobial peptides UBI29-41 and UBI18-35, ubiquicidin derivatives, for distinguishing between bacterial and aseptic inflammation. For radiolabeling of the peptides with technetium-99m, a bifunctional chelating agent succinimide-1-yl 6-(bis(pyridin-2-ylmethyl)amino)hexanoate was used. The obtained complexes ^99mТс-DPAH-UBI29-41 and ^99mТс-DPAH-UBI18-35 had radiolabeling yield >80% and radiochemical purity >96%. Accumulation of the complexes in the focus of bacterial inflammation in bone structures and the absence of this complex in the site of aseptic inflammation was confirmed in a rat model of traumatic osteomyelitis by single-photon emission computed tomography.

Design, recombinant expression, and antibacterial activity of a novel hybrid magainin-thanatin antimicrobial peptide

Antimicrobial peptides are small molecule polypeptides with biological activity, which can avoid the drug resistance. Magainin and thanatin are antimicrobial peptides with a broad spectrum of inhibitory microbes, and the core sequence of magainin is linked to a core sequence of thanatin. Here, the hybrid magainin-thanatin (MT) antimicrobial peptide was designed through bioinformatics analysis. The recombinant MT antimicrobial peptide was successfully expressed and purified in Escherichia coli BL21 (DE3). The molecular weight of the hybrid MT antimicrobial peptide was about 3.35 kDa. Moreover, the target protein indeed has an inhibitory effect on Staphylococcus aureus, E. coli DH5α, and Bacillus subtilis, with the minimum inhibitory concentrations 16.5, 20, and 9 μM, respectively. The rational designed hybrid MT antimicrobial peptide will hopefully provide large-scale fermentable antimicrobial peptides in the industrial production in the future.

Antimicrobial Peptides: Recent Insights on Biotechnological Interventions and Future Perspectives

With the unprecedented rise of drug-resistant pathogens, particularly antibiotic-resistant bacteria, and no new antibiotics in the pipeline over the last three decades, the issue of antimicrobial resistance has emerged as a critical public health threat. Antimicrobial Peptides (AMP) have garnered interest as a viable solution to this grave issue and are being explored for their potential antimicrobial applications. Given their low bioavailability in nature, tailoring new AMPs or strategizing approaches for increasing the yield of AMPs, therefore, becomes pertinent. The present review focuses on biotechnological interventions directed towards enhanced AMP synthesis and revisits existing genetic engineering and synthetic biology strategies for production of AMPs. This review further underscores the importance and potential applications of advanced gene editing technologies for the synthesis of novel AMPs in future.

Identification, Recombinant Expression, and Characterization of LHG2, a Novel Antimicrobial Peptide of Lactobacillus casei HZ1

L. casei HZ1 was identified from Chinese traditional fermented milk, and angiotensin converting enzyme inhibitory peptide was separated from its culture in our previous work. Here, LGH2 was a novel AMP, identified from the genome of L. casei HZ1. Altogether, roughly 52.76% of LGH2 was α-helical, with the remainder in β-strand and random coil in 50% TFE solution tested by CD. The peptide was also an amphipathic and cationic molecule, which was composed of 20 amino acid residues. The similarity of the amino acid sequence between LGH2 and Temporin-RN3 was highest. Then, the peptide successfully expressed in E. coli Rossetta (DE3) pLysS using the SUMO fusion expression system and purified by chromatography technologies. The molecular weight of the peptide was 2448 Da determined by MALDI-TOF MS. Antimicrobial tests showed that the peptide has strong activities against G+ bacteria, special for S. aureus (MIC = 4 μM). The toxicity assay showed that the peptide exhibits a low hemolytic activity against sheep red blood cells. The antimicrobial mechanisms of LGH2 against pathogens were further investigated by dye leakage, CLSM, SEM, and FCM assays. We found that LGH2 can bind to the cell membrane, and destroy its integrity. These significant results indicate that LGH2 has great potential to treat the infections caused by pathogenic bacteria such as S. aureus, and it provides a new template to improve antimicrobial peptides targeting antibiotic-resistant pathogenic bacteria.