Kaushal Akanksha, Gupta Kajal, van Hoek Monique L
Department of Biology, George Mason University, Manassas, VA, USA.
College of Sciences, George Mason University, Fairfax, VA 22030, United States.
Biochem Biophys Res Commun. 2016 Feb 19;470(4):955-60. doi: 10.1016/j.bbrc.2016.01.100. Epub 2016 Jan 21.
Antimicrobial peptides are components of both vertebrate and invertebrate innate immune systems that are expressed in response to exposure to bacterial antigens. Naturally occurring antimicrobial peptides from evolutionarily ancient species have been extensively studied and are being developed as potential therapeutics against antibiotic resistant microorganisms. In this study, a putative Cimex lectularius (bedbug, CL) defensin is characterized for its effectiveness against human skin flora including Gram-negative and Gram-positive bacteria. The bedbug defensin (CL-defensin), belonging to family of insect defensins, is predicted to have a characteristic N-terminal loop, an α-helix, and an antiparallel β-sheet, which was supported by circular dichroism spectroscopy. The defensin was shown to be antimicrobial against Gram-positive bacteria commonly found on human skin (Micrococcus luteus, Corynebacterium renale, Staphylococcus aureus and Staphylococcus epidermidis); however, it was ineffective against common skin Gram-negative bacteria (Pseudomonas aeruginosa and Acinetobacter baumannii) under low-salt conditions. CL-defensin was also effective against M. luteus and C. renale in high-salt (MIC) conditions. Our studies indicate that CL-defensin functions by depolarization and pore-formation in the bacterial cytoplasmic membrane.
抗菌肽是脊椎动物和无脊椎动物先天免疫系统的组成部分，它们在接触细菌抗原时表达。来自进化古老物种的天然抗菌肽已得到广泛研究，并正在开发成为对抗抗生素耐药微生物的潜在疗法。在本研究中，一种推定的温带臭虫防御素对包括革兰氏阴性菌和革兰氏阳性菌在内的人类皮肤菌群的有效性进行了表征。臭虫防御素（CL-防御素）属于昆虫防御素家族，预计具有特征性的N端环、α-螺旋和反平行β-折叠，这得到了圆二色光谱的支持。该防御素对人类皮肤上常见的革兰氏阳性菌（藤黄微球菌、肾棒状杆菌、金黄色葡萄球菌和表皮葡萄球菌）具有抗菌作用；然而，在低盐条件下，它对常见的皮肤革兰氏阴性菌（铜绿假单胞菌和鲍曼不动杆菌）无效。CL-防御素在高盐（MIC）条件下对藤黄微球菌和肾棒状杆菌也有效。我们的研究表明，CL-防御素通过使细菌细胞质膜去极化和形成孔道发挥作用。
