Tankrathok Anupong, Punpad Arpaporn, Kongchaiyapoom Monrudee, Sosiangdi Sirinthip, Jangpromma Nisachon, Daduang Sakda, Klaynongsruang Sompong
Department of Biotechnology, Faculty of Agricultural Technology, Kalasin University, Kalasin, Thailand.
Protein and Proteomics Research Center for Commercial and Industrial Purposes (ProCCI), Faculty of Science, Khon Kaen University, Khon Kaen, Thailand.
Biotechnol Appl Biochem. 2019 Mar;66(2):142-152. doi: 10.1002/bab.1709. Epub 2018 Nov 23.
Cathelicidins are effector molecules of vertebrate immunity that play vital roles against microbial invasion. They are widely identified in mammals, but few have been reported in Crocodilians, which are considered to be species with a powerful immune system. In the present study, we identified and characterized a novel cathelicidin from the blood of the Siamese crocodile, Crocodylus siamensis. A cDNA sequence (501 base pair) encoded a predicted 166-residue prepropeptide of C. siamensis cathelicidin (Cs-CATH), which comprised a 21-residue signal peptide, a 109-residue cathelin domain, and a 36-residue mature cathelicidin peptide. Multiple sequence alignment and phylogenetic analysis demonstrated that Cs-CATH shared a high degree of similarity with other crocodilian cathelicidins. Joint consideration of elastase cleavage site, physicochemical properties, and predicted secondary structure demonstrated that RN15 peptide is a candidate antimicrobial peptide derived from Cs-CATH. The synthetic RN15 peptide demonstrates antimicrobial activity against Gram-positive and Gram-negative bacteria. Scanning electron microscopy illustrated RN15-peptide-induced bacteria cells exhibited morphological change. Besides, RN15 peptide demonstrates low hemolytic activity against human erythrocytes and low cytotoxic activity against normal human dermal fibroblasts. This is the first cathelicidin identified from C. siamensis, and it is highlighted that its derived peptide from cathelin domain promises potent novel peptide antibiotics templates.
猫抗菌肽是脊椎动物免疫的效应分子，在抵抗微生物入侵中发挥着至关重要的作用。它们在哺乳动物中被广泛鉴定出来，但在被认为具有强大免疫系统的鳄鱼中却鲜有报道。在本研究中，我们从暹罗鳄（Crocodylus siamensis）的血液中鉴定并表征了一种新型猫抗菌肽。一个cDNA序列（501个碱基对）编码了暹罗鳄猫抗菌肽（Cs-CATH）预测的166个残基的前原肽，它由一个21个残基的信号肽、一个109个残基的组织蛋白酶原结构域和一个36个残基的成熟猫抗菌肽组成。多序列比对和系统发育分析表明，Cs-CATH与其他鳄鱼猫抗菌肽具有高度相似性。综合考虑弹性蛋白酶切割位点、理化性质和预测的二级结构表明，RN15肽是一种源自Cs-CATH的候选抗菌肽。合成的RN15肽对革兰氏阳性菌和革兰氏阴性菌均表现出抗菌活性。扫描电子显微镜显示，经RN15肽处理的细菌细胞呈现出形态变化。此外，RN15肽对人红细胞的溶血活性较低，对正常人皮肤成纤维细胞的细胞毒性活性也较低。这是首次从暹罗鳄中鉴定出的猫抗菌肽，值得注意的是，其从组织蛋白酶原结构域衍生的肽有望成为有效的新型肽抗生素模板。
