Two novel antimicrobial peptides from skin venoms of spadefoot toad Megophrys minor.
Amphibian skin contains rich bioactive peptides. Especially, a large amount of antimicrobial peptides have been identified from amphibian skin secretions. Antimicrobial peptides display potent cytolytic activities against a range of pathogenic bacteria and fungi and play important defense roles. No antimicrobial peptides have been reported from toads belonging to the family of Pelobatidae. In this work, two novel antimicrobial peptides (Megin 1 and Megin 2) were purified and characterized from the skin venoms of spadefoot toad Megophrys minor (Pelobatidae, Anura, Amphibia). Megin 1 had an amino acid sequence of FLKGCWTKWYSLKPKCPF-NH2, which was composed of 18 amino acid residues and contained an intra-molecular disulfide bridge and an amidated C-terminus. Megin 2 had an amino acid sequence of FFVLKFLLKWAGKVGLEHLACKFKNWC, which was composed of 27 amino acid residues and contained an intra-molecular disulfide bridge. Both Megin 1 and Megin 2 showed potential antimicrobial abilities against bacteria and fungi. The MICs of Megin 1 against Escherichia coli, Bacillus dysenteriae, Staphylococcus aureus, Bacillus subtilis, and Candida albicans were 25, 3, 6.25, 3, and 50 μg·mL(-1), respectively. The corresponding MICs for Megin 2 were 6.25, 1.5, 12.5, 1.5, and 12.5 μg·mL(-1), respectively. They also exerted strong hemolytic activity against human and rabbit red cells. The results suggested that megin peptides in the toad skin of M. minor displayed toxic effects on both eukaryotes and prokaryotes. This was the first report of antimicrobial peptides from amphibians belonging to the family of Pelobatidae.
School of Pharmaceutical Science and Yunnan Key Laboratory of Pharmacology for Natural Products, Kunming Medical University, Kunming, Yunnan 650500, China.
Hong-Ling
HL
Yang
School of Pharmaceutical Science and Yunnan Key Laboratory of Pharmacology for Natural Products, Kunming Medical University, Kunming, Yunnan 650500, China.
Zhi-Qiang
ZQ
Shen
School of Life Science & Technology, China Pharmaceutical University, Nanjing 210009, China.
Xuan
X
Liu
School of Life Science & Technology, China Pharmaceutical University, Nanjing 210009, China. Electronic address: yikong668@163.com.
Yi
Y
Kong
D000595:Amino Acid Sequence; D000664:Amphibian Venoms / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification*; D000818:Animals; D001001:Anura / Q000276:immunology*; D001407:Bacillus; D002176:Candida albicans; D004912:Erythrocytes / Q000502:physiology; D004926:Escherichia coli; D005260:Female; D006461:Hemolysis; D006801:Humans; D008297:Male; D010455:Peptides / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification*; D011817:Rabbits; D016415:Sequence Alignment; D012867:Skin / Q000737:chemistry / Q000276:immunology; D013211:Staphylococcus aureus
D000664:Amphibian Venoms; D010455:Peptides
Amphibian; Antimicrobial peptides; Pelobatidae; Skin venoms