National Academy of Sciences;United States: Proceedings of the National Academy of Sciences
摘要:
摘要： Melittin is a prototype of the ubiquitous antimicrobial peptides that induce pores in membranes. It is commonly used as a molecular device for membrane permeabilization. Even at concentrations in the nanomolar range, melittin can induce transient pores that allow transmembrane conduction of atomic ions but not leakage of glucose or larger molecules. At micromolar concentrations, melittin induces stable pores allowing transmembrane leakage of molecules up to tens of kilodaltons, corresponding to its antimicrobial activities. Despite extensive studies, aspects of the molecular mechanism for pore formation remain unclear. To clarify the mechanism, one must know the states of the melittin-bound membrane before and after the process. By correlating experiments using giant unilamellar vesicles with those of peptide-lipid multilayers, we found that melittin bound on the vesicle translocated and redistributed to both sides of the membrane before the formation of stable pores. Furthermore, stable pores are formed only above a critical peptide-to-lipid ratio. The initial states for transient and stable pores are different, which implies different mechanisms at low and high peptide concentrations. To determine the lipidic structure of the pore, the pores in peptide–lipid multilayers were induced to form a lattice and examined by anomalous X-ray diffraction. The electron density distribution of lipid labels shows that the pore is formed by merging of two interfaces through a hole. The molecular property of melittin is such that it adsorbs strongly to the bilayer interface. Pore formation can be viewed as the bilayer adopting a lipid configuration to accommodate its excessive interfacial area. 其他題名： Proc Natl Acad Sci U S A 出版者： United States: Proceedings of the National Academy of Sciences 出版日期： 2013-08-27 出處： Proceedings of the National Academy of Sciences, 2013-08, Vol.110 (35), p.14243-14248 資源來源： JSTOR Life Sciences Collection 版權： Copyright National Academy of Sciences 版權： Copyright National Academy of Sciences Aug 27, 2013 識別號： ISSN: 0027-8424 識別號： ISSN: 1091-6490 識別號： EISSN: 1091-6490 識別號： DOI: 10.1073/pnas.1307010110 識別號： PMID: 23940362
