Recombinant Production of Crab Antimicrobial Protein Scygonadin Expressed as Thioredoxin and SUMO Fusions in Escherichia coli

Development strategies and application of antimicrobial peptides as future alternatives to in-feed antibiotics

The use of in-feed antibiotics has been widely restricted due to the significant environmental pollution and food safety concerns they have caused. Antimicrobial peptides (AMPs) have attracted widespread attention as potential future alternatives to in-feed antibiotics owing to their demonstrated antimicrobial activity and environment friendly characteristics. However, the challenges of weak bioactivity, immature stability, and low production yields of natural AMPs impede practical application in the feed industry. To address these problems, efforts have been made to develop strategies for approaching the AMPs with enhanced properties. Herein, we summarize approaches to improving the properties of AMPs as potential alternatives to in-feed antibiotics, mainly including optimization of structural parameters, sequence modification, selection of microbial hosts, fusion expression, and industrially fermentation control. Additionally, the potential for application of AMPs in animal husbandry is discussed. This comprehensive review lays a strong theoretical foundation for the development of in-feed AMPs to achieve the public health globally.

Simple and rapid pipeline for the production of cyclic and linear small-sized peptides in E. coli

Small and medium-sized peptides are gaining popularity in biomedical applications, including therapeutic target development. As an alternative to chemical synthesis, we describe a complete pipeline for the production of linear as well as structurally constrained cyclic peptides in an E. coli expression system in this study. A plasmid vector containing a novel N terminal HOE tag (28 amino acids in length) that fuses with the peptide was created. The HOE tag contains sites for both chemical (CNBr) and enzymatic (enterokinase) cleavage, making it easy to isolate the peptide after production. A total of 21 peptides (17 cyclic and 4 linear) were synthesized, and the HOE tag was successfully removed using either CNBr (9 peptides) or enterokinase (12 peptides). The presence of a disulfide bond was confirmed in six representative cyclic peptides. In this study we have provided detailed instructions on primers design strategy, overexpression and purification of HOE tagged peptides, chemical and enzymatic cleavage, and confirmation of the cyclic form of peptides. We are confident that this pipeline will assist researchers in producing multiple recombinant peptides in a cost-effective and time-efficient manner.

Venom peptides - A comprehensive translational perspective in pain management

Venom peptides have been evolving complex therapeutic interventions that potently and selectively modulate a range of targets such as ion channels, receptors, and signaling pathways of physiological processes making it potential therapeutic. Several venom peptides were deduced in vivo for clinical development targeting pain management, diabetes, cardiovascular diseases, antimicrobial activity. Several contributions have been detailed for a clear perspective for a better understanding of venomous animals, their venom, and their pharmacological effects. Here we unravel and summarize the recent advances in wide venom peptides across varieties of species for their therapeutics prospects.

Recombinant Production and Characterization of SAC, the Core Domain of Par-4, by SUMO Fusion System

Prostate apoptosis response-4 (Par-4), an anticancer protein that interacts with cell surface receptor GRP78, can selectively suppress proliferation and induce apoptosis of cancer cells. The core domain of Par-4 (aa 137-195), designated as SAC, is sufficient to inhibit tumor growth and metastasis without harming normal tissues and organs. Nevertheless, the anticancer effects of SAC have not been determined in ovarian cancer cells. Here, we developed a novel method for producing native SAC in Escherichia coli using a small ubiquitin-related modifier (SUMO) fusion system. This fusion system not only greatly improved the solubility of target protein but also enhanced the expression level of SUMO-SAC. After purified by Ni-NTA affinity chromatography, SUMO tag was cleaved from SUMO-SAC fusion protein using SUMO protease to obtain recombinant SAC. Furthermore, we simplified the purification process by combining the SUMO-SAC purification and SUMO tag cleavage into one step. Finally, the purity of recombinant SAC reached as high as 95% and the yield was 25 mg/L. Our results demonstrated that recombinant SAC strongly inhibited proliferation and induced apoptosis in ovarian cancer cells SKOV-3. Immunofluorescence analysis and competitive binding reaction showed that recombinant SAC could specifically induce apoptosis of SKOV-3 cells through combination with cell surface receptor, GRP78. Therefore, we have developed an effective strategy for expressing bioactive SAC in prokaryotic cells, which supports the application of SAC in ovarian cancer therapy.

Promoting Tag Removal of a MBP-Fused Integral Membrane Protein by TEV Protease

Tag removal is a prerequisite issue for structural and functional analysis of affinity-purified membrane proteins. The present study took a MBP-fused membrane protein, MrpF, as a model to investigate the tag removal by TEV protease. Influences of the linking sequence between TEV cleavage site and MrpF on protein expression and predicted secondary structure were investigated. The steric accessibility of TEV protease to cleavage site of MBP-fused MrpF was explored. It was found that reducing the size of hydrophilic group of detergents and/or extending the linking sequence between cleavage site and target protein can significantly improve the accessibility of the cleavage site and promote tag removal by TEV protease.