Structure of the alamethicin pore reconstructed by x-ray diffraction analysis |
| |
Authors: | Qian Shuo Wang Wangchen Yang Lin Huang Huey W |
| |
Institution: | * Department of Physics and Astronomy, Rice University, Houston, Texas 77251 † National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 |
| |
Abstract: | We reconstructed the electron density profile of the alamethicin-induced transmembrane pore by x-ray diffraction. We prepared fully hydrated multiple bilayers of alamethicin-lipid mixtures in a condition where pores were present, as established previously by neutron in-plane scattering in correlation with oriented circular dichroism. At dehydrated conditions, the interbilayer distance shortened and the interactions between bilayers caused the membrane pores to become long-ranged correlated and form a periodically ordered lattice of rhombohedral symmetry. To resolve the phase problem of diffraction, we used a brominated lipid and performed multiwavelength anomalous diffraction at the bromine K edge. The result unambiguously shows that the alamethicin pore is of the barrel-stave type consisting of eight alamethicin helices. This pore structure corresponds to the stable pores detected by neutron in-plane scattering in fully hydrated fluid bilayers at high peptide/lipid ratios, which are the conditions at which alamethicin was tested for its antibacterial activity. |
| |
Keywords: | |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|