1. The Central Hinge Link Truncation of the Antimicrobial Peptide Fowlicidin-3 Enhances Its Cell Selectivity without Antibacterial Activity Loss
Pei Qu, Wei Gao, Huixian Chen, Dan Li, Na Yang, Jian Zhu, Xingjun Feng, Chunlong Liu, Zhongqiu Li Antimicrob Agents Chemother. 2016 Apr 22;60(5):2798-806. doi: 10.1128/AAC.02351-15. Print 2016 May.
Antimicrobial peptides (AMPs) have been paid considerable attention because of their broad-spectrum antimicrobial activity and a reduced possibility of the development of bacterial drug resistance. Fowlicidin-3 (Fow-3) is an identified type of chicken cathelicidin AMP that has exhibited considerable antimicrobial activity and cytotoxicity. To reduce cell toxicity and improve cell selectivity, several truncated peptides of fowlicidin-3, Fow-3(1-15), Fow-3(1-19), Fow-3(1-15-20-27), and Fow-3(20-27), were synthesized. Our results indicated that neither the N- nor C-terminal segment alone [Fow-3(1-15), Fow-3(1-19), Fow-3(20-27)] was sufficient to confer antibacterial activity. However, Fow-3(1-19) with the inclusion of the central hinge link (-AGIN-) retained substantial cell toxicity, which other analogs lost. Fow-3(1-15-20-27) displayed potent antimicrobial activity for a wide range of Gram-negative and Gram-positive bacteria and no obvious hemolytic activity or cytotoxicity. The central link region was shown to be critically important in the function of cell toxicity but was not relevant to antibacterial activity. Fow-3(1-15-20-27) maintained antibacterial activity in the presence of physiological concentrations of salts. The results from fluorescence spectroscopy, scanning electron microcopy, and transmission electron microcopy showed that Fow-3(1-15-20-27) as well as fowlicidin-3 killed bacterial cells by increasing membrane permeability and damaging the membrane envelope integrity. Fow-3(1-15-20-27) could be a promising antimicrobial agent for clinical application.
2. Transient expression of chicken antimicrobial peptides by mouse mammary carcinoma cells C127
Na Yi, Ning Li Protein Pept Lett. 2010 Dec;17(12):1517-23. doi: 10.2174/0929866511009011517.
Fowlicidin-3 and fowlicidin-1 are cathelicidin-type antimicrobial peptides found in chicken. They effectively inhibit the proliferation of many gram-positive and gram-negative bacteria. To obtain sufficient amounts of these peptides for possible use in therapeutic applications, DNA encoding each full-length gene, including all exons and introns, was fused to the β-casein promoter in a pBC1 vector that was then introduced into C127 cells. The full-length precursor proteins were expressed in response to a mixture of insulin, hydrocortisone, and prolactin. Processed fowlicidin-1 and fowlicidin-3, as well as their precursors, were found in the cell culture media, which suggested that they could be processed and secreted. These transgenic peptides had antibacterial activity. Thus, transfected C127 cells may serve as an in vitro transgenic cell system that can be used to evaluate if specific gene constructs can be efficiently expressed in the mammary glands of transgenic mice.
3. Fowlicidin-3 is an alpha-helical cationic host defense peptide with potent antibacterial and lipopolysaccharide-neutralizing activities
Yugendar R Bommineni, Huaien Dai, Yu-Xi Gong, Jose L Soulages, Samodha C Fernando, Udaya Desilva, Om Prakash, Guolong Zhang FEBS J. 2007 Jan;274(2):418-28. doi: 10.1111/j.1742-4658.2006.05589.x.
Cathelicidins are an important family of cationic host defense peptides in vertebrates with both antimicrobial and immunomodulatory activities. Fowlicidin-1 and fowlicidin-2 are two newly identified chicken cathelicidins with potent antibacterial activities. Here we report structural and functional characterization of the putatively mature form of the third chicken cathelicidin, fowlicidin-3, for exploration of its therapeutic potential. NMR spectroscopy revealed that fowlicidin-3 comprises 27 amino-acid residues and adopts a predominantly alpha-helical structure extending from residue 9 to 25 with a slight kink induced by a glycine at position 17. It is highly potent against a broad range of Gram-negative and Gram-positive bacteria in vitro, including antibiotic-resistant strains, with minimum inhibitory concentrations in the range 1-2 microM. It kills bacteria quickly, permeabilizing cytoplasmic membranes immediately on coming into contact with them. Unlike many other host defense peptides with antimicrobial activities that are diminished by serum or salt, fowlicidin-3 retains bacteria-killing activities in the presence of 50% serum or physiological concentrations of salt. Furthermore, it is capable of suppressing lipopolysaccharide-induced expression of proinflammatory genes in mouse macrophage RAW264.7 cells, with nearly complete blockage at 10 microM. Fowlicidin-3 appears to be an excellent candidate for future development as a novel antimicrobial and antisepsis agent, particularly against antibiotic-resistant pathogens.
