Small-Anion Selective Transmembrane 鈥淗oles鈥?Induced by an Antimicrobial Peptide Too Short to Span Membranes

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• 作者：Kan Hu ; Yunjiang Jiang ; Yuntao Xie ; Hui Liu ; Rui Liu ; Zhi Zhao ; Ren Lai ; Lihua Yang
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：July 9, 2015
• 年：2015
• 卷：119
• 期：27
• 页码：8553-8560
• 全文大小：385K
• ISSN：1520-5207

文摘

Whereas many membrane-destabilization modes have been suggested for membrane-spanning antimicrobial peptides (AMPs), few are available for those too short to span membrane thickness. Here we show that ORB-1, a 15-residue disulfide-bridged AMP that is only 鈭?0 脜 long even when fully stretched like a hairpin, may act by inducing small anion-selective transmembrane 鈥渉oles鈥?of negative mean curvature. In model membranes of Gram-negative bacteria, ORB-1 induces chloride transmembrane transport and formation of transmembrane channels of negative mean curvature, whereas the inactive analogue, ORB-N, does not, suggesting a correlation between antibacterial activity and ability to induce transmembrane channels. Given that ORB-N is the C-terminus amidated form of ORB-1, our results further suggest that formation of membrane-spanning dimers may be required to initiate the observed channel induction. Moreover, ORB-1 renders model bacterial membranes permeable to anions with effective hydration diameters of <1 nm (e.g., Cl^{鈥?/sup> and NO₃鈥?/sup>), but not cations of similar sizes (e.g., H₃O+), indicative of anion-selective transmembrane channels with an effective inner diameter of 鈮? nm. In addition, negative-intrinsic-curvature (NIC) lipids such as phosphoethanolamine (PE) may facilitate the membrane-destabilization process of ORB-1. Our findings may expand current understandings on how AMPs destabilize membranes and facilitate the pharmaceutical development of ORB-1.}