Interactions of monomeric rabbit neutrophil defensins with bilayers: Comparison with dimeric human defensin HNP-2
Interactions of monomeric rabbit neutrophil defensins with bilayers: Comparison with dimeric human defensin HNP-2
复制标题
DOI：
10.1021/bi961100d
复制
发表时间：
1996-09-10
期刊：
影响因子：
2.9
通讯作者：
White, SH
中科院分区：
文献类型：
--
作者：
Hristova, K;Selsted, ME;White, SH
人抗微生物嗜中性粒细胞防御素HNP-2已显示在纯1-棕榈酰-2-油酰磷脂酰甘油（POPG）双层中形成大的多聚体孔，其导致囊泡内容物的全部或无释放[Wimley等人（1994）Protein Sci. 3，1362-1373]。由于人中性粒细胞防御素在溶液中形成天然二聚体，因此出现了二聚化在孔形成中的作用的问题。然而，二聚体是如此稳定，这个问题是不容易直接回答，兔中性粒细胞防御素，其三维结构是非常相似的人防御素，在水溶液中是单体，从而提供了一个机会来测试的假设，二聚化可能发挥作用，在多聚体孔形成。因此，我们研究了六种已知的兔中性粒细胞防御素与大单层囊泡（LUV）的相互作用，在已知的条件下，导致HNP-2形成稳定的孔。我们发现，兔防御素强烈结合LUVs形成的纯POPG或混合物的POPG与中性（两性离子）磷脂，但诱导泄漏的囊泡内容物仅从纯POPG囊泡。兔防御素NP-4在任何检测条件下均不引起渗漏。其余的防御素NP-1、NP-2、NP-3A、NP-3B和NP-5。导致咕噜声：POPG囊泡的内容物的分级释放，就像六种防御素的混合物一样。分级释放表明兔防御素在膜中不形成稳定的孔。因此，这一结果表明，允许在水溶液中形成二聚体的人防御素的结构特征可能是重要的多聚体端口的形成。
Human antimicrobial neutrophil defensin HNP-2 has been shown to form large multimeric pores in pure 1-palmitoyl-2-oleoyl phosphatidylglycerol (POPG) bilayers that lead to all-or-none release of vesicle contents [Wimley et al. (1994) Protein Sci. 3, 1362-1373]. Because human neutrophil defensins form natural dimers in solution, the question arises as to the role of dimerization in pore formation. However, the dimers are so stable that this question is not easily answered directly, Rabbit neutrophil defensins, whose three-dimensional structures are very similar to those of human defensins, are monomeric in aqueous solution and thus provide an opportunity to test the hypothesis that dimerization may play a role in multimeric pore formation. We therefore examined the interactions of the six known rabbit neutrophil defensins with large unilamellar vesicles (LUV) under the conditions known to lead to stable pore formation by HNP-2. We find that the rabbit defensins bind strongly to LUVs formed from pure POPG or mixtures of POPG with neutral (zwitterionic) phospholipid but induce leakage of vesicle contents only from pure POPG vesicles. Rabbit defensin NP-4 does not cause leakage under any conditions examined. The remaining defensins, NP-1, NP-2, NP-3A, NP-3B, and NP-5. cause graded release of the contents of purr: POPG vesicles as does a mixture of the six defensins. The graded release indicates that the rabbit defensins do not form stable pores in the membrane. This result thus suggests that the structural features of human defensins that permit dimer formation in aqueous solution are likely to be important in the formation of multimeric ports.