1. Two novel antimicrobial peptides purified from the symbiotic bacteria Xenorhabdus budapestensis NMC-10
Yao Xiao, Fanlu Meng, Dewen Qiu, Xiufen Yang Peptides. 2012 Jun;35(2):253-60. doi: 10.1016/j.peptides.2012.03.027. Epub 2012 Apr 3.
Symbiotic bacteria, which are carried in the intestinal vesicle of the infective stage of juvenile entomopathogenic nematodes, produce broad-spectrum antibiotics. In this study, we aimed to isolate the antimicrobial peptides from the culture of the entomopathogenic bacterium Xenorhabdus budapestensis NMC-10. By screening chromatography columns and optimizing flow rate, pH, salinity and other purification conditions, we identified the final purification procedures which consisted of Q ion-exchange chromatography, gel filtration chromatography and two-step reverse-phase chromatography. Two novel antimicrobial peptides were identified via Q-TOF-TOF and de novo sequencing, and designated as GP-19 and EP-20. Both natural and synthetic peptides demonstrated broad-spectrum antimicrobial activities. The synthetic GP-19 peptide was active against Verticillium dahlia with EC(50) values of 17.54 μg/ml and highly inhibited the growth of a variety of bacteria, while the synthetic EP-20 peptide was highly active against Phytophthora capsici with EC(50) values of 3.14 μg/ml.
2. Tostadin, a novel antibacterial peptide from an antagonistic microorganism Brevibacillus brevis XDH
Zhen Song, Qingxin Liu, Hui Guo, Ruicheng Ju, Yuhua Zhao, Jinyu Li, Xunli Liu Bioresour Technol. 2012 May;111:504-6. doi: 10.1016/j.biortech.2012.02.051. Epub 2012 Feb 18.
A novel small antibacterial peptide was obtained from the liquid culture of Brevibacillus brevis XDH, which is a broad-spectrum antagonistic bacterium isolated from the soil of Mountain Tai, China. This peptide was purified from the fermentation medium of strain XDH via ammonium sulfate precipitation, cation exchange chromatography, and reversed-phase high-performance liquid chromatography (HPLC), successively. The structure of the active linear peptide was elucidated using mass spectra (MS) and nuclear magnetic resonance (NMR) analyses that consisted of nine amino acids. This peptide was easily soluble in water, thermally stable and strongly inhibited the growth of Escherichia coli and Staphylococcus aureus in vitro. The present data support the identification of a novel antibacterial peptide, which was named Tostadin.
3. Purification, characterization, and sequencing of antimicrobial peptides, Cy-AMP1, Cy-AMP2, and Cy-AMP3, from the Cycad (Cycas revoluta) seeds
Seiya Yokoyama, Kouji Kato, Atsuko Koba, Yuji Minami, Keiichi Watanabe, Fumio Yagi Peptides. 2008 Dec;29(12):2110-7. doi: 10.1016/j.peptides.2008.08.007. Epub 2008 Aug 20.
Novel antimicrobial peptides (AMP), designated Cy-AMP1, Cy-AMP2, and Cy-AMP3, were purified from seeds of the cycad (Cycas revoluta) by a CM cellulofine column, ion-exchange HPLC on SP COSMOGEL, and reverse-phase HPLC. They had molecular masses of 4583.2 Da, 4568.9 Da and 9275.8 Da, respectively, by MALDI-TOF MS analysis. Half of the amino acid residues of Cy-AMP1 and Cy-AMP2 were cysteine, glycine and proline, and their sequences were similar. The sequence of Cy-AMP3 showed high homology to various lipid transfer proteins. For Cy-AMP1 and Cy-AMP2, the concentrations of peptides required for 50% inhibition (IC(50)) of the growth of plant pathogenic fungi, Gram-positive and Gram-negative bacteria were 7.0-8.9 microg/ml. The Cy-AMP3 had weak antimicrobial activity. The structural and antimicrobial characteristics of Cy-AMP1 and Cy-AMP2 indicated that they are a novel type of antimicrobial peptide belonging to a plant defensin family.
