Cathelicidins from the bullfrog Rana catesbeiana provides novel template for peptide antibiotic design

• Published in: PloS one 2014-03, Vol.9 (3), p.e93216-e93216
• Main Authors: Ling, Guiying, Gao, Jiuxiang, Zhang, Shumin, Xie, Zeping, Wei, Lin, Yu, Haining, Wang, Yipeng
• Format: Article
• Language: English
• Subjects: Acne; Amino Acid Sequence; Amphibia; Amphibians; Analysis; Animals; Antibiotics; Antiinfectives and antibacterials; Antimicrobial activity; Antimicrobial Cationic Peptides - chemistry; Antimicrobial Cationic Peptides - genetics; Antimicrobial Cationic Peptides - pharmacology; Bacteria; Base Sequence; Biology and Life Sciences; Biotechnology; Birds; Cathelicidins; Cathelicidins - chemistry; Cathelicidins - genetics; Cathelicidins - pharmacology; Circular Dichroism; Conformation; Cytotoxicity; Design; DNA, Complementary - chemistry; DNA, Complementary - genetics; Drug Design; Electron microscopy; Erythrocytes; Genomic libraries; Hemolysis - drug effects; Humans; Immune system; Immunity; Innate immunity; Killing; Kinetics; Library collections; Lungs; Mammals; Medicine and Health Sciences; Microbial Sensitivity Tests; Microorganisms; Models, Molecular; Molecular Sequence Data; Neutrophils; Peptide antibiotics; Peptides; Pharmaceutical sciences; Phylogenetics; Phylogeny; Physical Sciences; Protein Structure, Secondary; Rana catesbeiana; Rana catesbeiana - classification; Rana catesbeiana - genetics; Red blood cells; Reptiles; Reptiles & amphibians; Salt-Tolerance; Salts; Scanning electron microscopy; Sequence Alignment; Structural analysis; Tumor cell lines
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0093216

Cathelicidins, a class of gene-encoded effector molecules of vertebrate innate immunity, provide a first line of defense against microbial invasions. Although cathelicidins from mammals, birds, reptiles and fishes have been extensively studied, little is known about cathelicidins from amphibians. Here we report the identification and characterization of two cathelicidins (cathelicidin-RC1 and cathelicidin-RC2) from the bullfrog Rana catesbeiana. The cDNA sequences (677 and 700 bp, respectively) encoding the two peptides were successfully cloned from the constructed lung cDNA library of R. catesbeiana. And the deduced mature peptides are composed of 28 and 33 residues, respectively. Structural analysis indicated that cathelicidin-RC1 mainly assumes an amphipathic alpha-helical conformation, while cathelicidin-RC2 could not form stable amphipathic structure. Antimicrobial and bacterial killing kinetic analysis indicated that the synthetic cathelicidin-RC1 possesses potent, broad-spectrum and rapid antimicrobial potency, while cathelicidin-RC2 exhibited very weak antimicrobial activity. Besides, the antimicrobial activity of cathelicidin-RC1 is salt-independent and highly stable. Scanning electron microscopy (SEM) analysis indicated that cathelicidin-RC1 kills microorganisms through the disruption of microbial membrane. Moreover, cathelicidin-RC1 exhibited low cytotoxic activity against mammalian normal or tumor cell lines, and low hemolytic activity against human erythrocytes. The potent, broad-spectrum and rapid antimicrobial activity combined with the salt-independence, high stability, low cytotoxic and hemolytic activities make cathelicidin-RC1 an ideal template for the development of novel peptide antibiotics.