CHANNEL-FORMING PROPERTIES OF CECROPINS AND RELATED MODEL COMPOUNDS INCORPORATED INTO PLANAR LIPID-MEMBRANES
CHANNEL-FORMING PROPERTIES OF CECROPINS AND RELATED MODEL COMPOUNDS INCORPORATED INTO PLANAR LIPID-MEMBRANES
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DOI：
10.1073/pnas.85.14.5072
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发表时间：
1988-07-01
影响因子：
11.1
通讯作者：
MAUZERALL, D
中科院分区：
文献类型：
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作者：
CHRISTENSEN, B;FINK, J;MAUZERALL, D
天蚕素、天蚕蛾体内发现的带正电荷的抗菌肽和合成肽类似物在生理浓度范围内在平面脂膜上形成大的时变和电压依赖性离子通道。观察到了高达2.5 ns的单通道电导(在0.1M的氯化钠中)，这意味着通道直径为4 nm。抗菌肽AD与MP3形成的通道在0.1M的氯化钠溶液中的通透性比为2：1。通过对三种天蚕素A、B和D以及六种合成类似物的比较研究，可以确定孔隙形成的结构要求。较短的两亲性多肽虽然吸附在双层上，但不形成通道。在多肽的N-端两亲区和C-端更疏水区域之间需要一个灵活的片段来观察时变的、电压依赖的电导。天蚕素AD是最有效的电压依赖成孔肽，也是对几种受试物最有效的抗菌肽。双分子层中的正表面电荷或胆固醇使抗菌肽AD或MP3引起的电导减少至少5倍。这一行为与已知的真核细胞对天蚕素不敏感的现象是一致的。我们的观察表明，天蚕素的广泛抗菌活性是由于细菌细胞膜上形成了大孔所致。
Cecropins, positively charged antibacterial peptides found in the cecropia moth, and synthetic peptide analogs form large time-variant and voltage-dependent ion channels in planar lipid membranes in the physiological range of concentration. Single-channel conductances of up to 2.5 nS (in 0.1 M NaCl) were observed, which suggests a channel diameter of 4 nm. Channels formed by the peptides cecropin AD and MP3 had a permeability ratio of Cl-/Na+ = 2:1 in 0.1M NaCl. A comparative study of the three cecropins, cecropins A, B, and D, and of six synthetic analogs allowed determination of structural requirements for pore formation. Shorter amphipathic peptides did not form channels, although they adsorbed to the bilayer. A flexible segment between the N-terminal amphipathic region and the C-terminal more hydrophobic region of the peptide was required for the observation of a time-variant, voltage-dependent conductance. Cecropin AD was the most effective voltage-dependent pore-forming peptide and was also the most potent antibacterial peptide against several test organisms. A positive surface charge or cholesterol in the bilayer reduced the conductances caused by cecropin AD or MP3 by at least 5-fold. This behavior is consistent with the known insensitivity of eukaryotic cells to cecropins. Our observations suggest that the broad antibacterial activity of cecropins is due to formation of large pores in bacterial cell membranes.