INTERACTIONS OF AN ANTIMICROBIAL PEPTIDE, TACHYPLESIN-I, WITH LIPID-MEMBRANES
INTERACTIONS OF AN ANTIMICROBIAL PEPTIDE, TACHYPLESIN-I, WITH LIPID-MEMBRANES
复制标题
DOI：
10.1016/0005-2736(91)90173-6
复制
发表时间：
1991-11-18
期刊：
影响因子：
--
通讯作者：
MIYAJIMA, K
中科院分区：
文献类型：
--
作者：
MATSUZAKI, K;FUKUI, M;MIYAJIMA, K
从中国鲎（Tachypleus tridentatus）血细胞的酸性提取物中分离的鲎素I是一种环状广谱抗菌肽，由于两个分子内S-S键而形成刚性的、反平行的β折叠。 肽与脂多糖的强结合不能解释革兰氏阳性细菌和真菌对肽的亲和性。 我们发现，tachyplesin I引起快速K+流出大肠杆菌细胞，伴随着细胞活力降低。 这一结果表明，肽诱导的细菌膜的渗透性增强可能是一个合理的作用机制。 因此，我们研究了鲎素I与各种大单层囊泡（LUV）的相互作用，以揭示抗菌活性的分子机制。 Tachyplesin I诱导钙黄绿素（一种捕获的荧光标记物）从酸性磷脂（特别是磷脂酰甘油（PG））的LUV中泄漏，但不从磷脂酰胆碱LUV中泄漏。 详细的分析发现，肽对PG膜的亲和力非常强，并且一个肽分子与大约100个肽分子的结合是不稳定的。200个脂质分子导致显著泄漏。 通过使用肽的Trp-2荧光来估计鲎素I在膜中的位置。 PG LUV的存在下，引起的最大波长的蓝移，量子产率的增加，并从荧光猝灭的水溶液，丙烯酰胺的完全保护。 此外，由n-doxylstearates的色氨酸残基的荧光猝灭的程度是在顺序n = 5 > 7 > 12 - 16。 这些结果表明，鲎素I的色氨酸残基似乎位于PG双层表面附近的疏水环境中。
Tachyplesin I, isolated from the acid extracts of hemocytes of Tachypleus tridentatus, is a cyclic broad-spectrum antimicrobial peptide forming a rigid, antiparallel beta-sheet because of two intramolecular S-S linkages. The strong binding of the peptide to lipopolysaccharides cannot explain the susceptibilities of gram positive bacteria and fungi to the peptide. We found that tachyplesin I caused a rapid K+ efflux from Escherichia coli cells, concomitant with a reduced cell viability. This result suggests that the peptide-induced permeability enhancement of the bacterial membranes may be a plausible action mechanism. Thus, we studied the interactions of tachyplesin I with various large unilamellar vesicles (LUVs) to reveal the molecular machinery of the antimicrobial activity. Tachyplesin I induced the leakage of calcein, a trapped fluorescent marker, from LUVs of acidic phospholipids, especially phosphatidylglycerol (PG), but not from phosphatidylcholine LUVs. A detailed analysis found that the affinity of the peptide to the PG membranes is very strong and that the binding of one peptide molecule to approx. 200 lipid molecules leads to a significant leakage. The location of tachyplesin I in membranes was estimated by use of the Trp-2 fluorescence of the peptide. The presence of PG LUVs caused a blue shift of the maximum wavelength, an increase in the quantum yield, and a complete protection from fluorescence quenching by an aqueous quencher, acrylamide. Moreover, the degree of fluorescence quenching of the Trp residue by n-doxylstearates was in the order n = 5 > 7 > 12 congruent-to 16. These results show that the Trp residue of tachyplesin I seems to locate in a hydrophobic environment near the surface of the PG bilayers.