Barrel-stave model or toroidal model? A case study on melittin pores
Barrel-stave model or toroidal model? A case study on melittin pores
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DOI：
10.1016/s0006-3495(01)75802-x
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发表时间：
2001-09-01
影响因子：
3.4
通讯作者：
Huang, HW
中科院分区：
文献类型：
--
作者：
Yang, L;Harroun, TA;Huang, HW
由两亲性肽（包括蜂毒肽）诱导的跨膜孔通常在丙甲霉素孔之后用桶壁模型建模。我们通过使用两种方法，定向圆二色性（OCD）检测蜂毒肽螺旋的方向和中子散射检测跨膜孔的蜂毒肽检查这一假设。系统地测定了蜂毒肽的OCD光谱。蜂毒肽可以垂直或平行于脂质双层定向，这取决于双层的物理条件和组成。当螺旋垂直于双层平面取向时，检测到跨膜孔，而不是当螺旋平行于双层取向时。对导致丙甲霉素桶壁模型和爪蟾抗菌肽环形模型的证据进行了综述。蜂毒素孔的性质与爪蟾抗菌肽的性质非常相似，但与丙甲霉素的性质不同。我们的结论是，在自然产生的肽，我们已经调查，只有丙甲霉素符合桶壁模型。其他肽，包括爪蟾抗菌肽，蜂毒肽和protegrins，都出现诱导跨膜孔，符合环形模型，其中脂质单层弯曲连续通过孔，使水核心内衬的肽和脂质头基。
Transmembrane pores induced by amphiphilic peptides, including melittin, are often modeled with the barrel-stave model after the alamethicin pore. We examine this assumption on melittin by using two methods, oriented circular dichroism (OCD) for detecting the orientation of melittin helix and neutron scattering for detecting transmembrane pores. OCD spectra of melittin were systematically measured. Melittin can orient either perpendicularly or parallel to a lipid bilayer, depending on the physical condition and the composition of the bilayer. Transmembrane pores were detected when the helices oriented perpendicularly to the plane of the bilayers, not when the helices oriented parallel to the bilayers. The evidence that led to the barrel-stave model for alamethicin and that to the toroidal model for magainin were reviewed. The properties of melittin pores are closely similar to that of magainin but unlike that of alamethicin. We conclude that, among naturally produced peptides that we have investigated, only alamethicin conforms to the barrel-stave model. Other peptides, including magainins, melittin and protegrins, all appear to induce transmembrane pores that conform to the toroidal model in which the lipid monolayer bends continuously through the pore so that the water core is lined by both the peptides and the lipid headgroups.