Team:HZAU-China/Project/Antimicrobial Peptides

• Overview
• The innovation of HZAU-iGEM Team
• The design of experiment
• Rabies
• Flea and Yersinia pestis
• Bacterial Spores as Vaccine Vehicles
• Bacillus subtilis as Probiotics
• Antimicrobial Peptides
• Methods for rearing flea

Antimicrobial peptides(AMPs)

As we can see today, numerous pathogens have developed an increasing resistance to commonly used prescribed antibiotics after years of intensive overuse. Hence antimicrobial peptides show their profound advantage over classical antibiotics. AMP is a peptide that derived from human or some animals/plants. AMPs can rapidly kill a broad range of microbes including Gram positive and Gram negative, and have additional activities that can affect the quality and effectiveness of the innate immune response. Furthermore, AMPs’ unique action mode makes them less likely to cause resistance in pathogens. They are active over a broad pH range and could survive temperatures up to 100℃. Compared to natural peptides, synthetic AMPs show less toxic side effects, and are, until now, safe to be used in combination with gene therapy. Therefore, we took into consideration two AMPs, Lactoferrin and Human Lysozyme, in our project to kill bacteria.

Lactoferrin

Lactoferrin (Lf) is a multifunctional member of the transferrin. Lf is found at the mucosal surface where it functions as a prominent component of the first line of the host defense system against infection and inflammation. This protein has a broad spectrum of anti-infection and anti-inflammatory function. Also, lactoferrin has a broad anti-bacterial range and strong anti-bacterial activity resulting from depolarization of the membrane, increased membrane permeability and metabolism injury.

Human Lysozyme

Human lysozyme (hLZ), the major protein in breast milk, exhibits microbicidal activity to various degrees against several bacterial strains. The helix-loop-helix(HLH) peptide and its N-terminal helix (H1) were the most potent bactericidal to bacteria. Evidence shows that HLH peptide and its N-terminal helix (H1) kill bacteria by crossing the outer membrane of Gram-negative bacteria via self-promoted uptake and is able to dissipate the membrane-potential-dependent respiration of Gram-positive bacteria.

Reference

1. Shin JR, Lim KJ, et al. Display of Multimeric Antimicrobial Peptides on the Escherichia coli Cell Surface and Its Application as Whole-Cell Antibiotics. PLoS ONE, 2013;8(3): e58997. doi:10. 1371/journal.pone.0058997

2. Lei X, Wanghui X et al. Facile expression and purification of the antimicrobial peptide histatin 1 with a cleavable self-aggregating tag(cSAT) in Escherichia coli. Protein Expression and Purification 2013;88:248-253.

3. Jang SA, Kim H et al. Mechanism of action and specificity of antimicrobial peptides designed based on buforin IIb. Peptides 2012;34:283-289.