Crystallization of bacteriorhodopsin from bicelle formulations at room temperature
Crystallization of bacteriorhodopsin from bicelle formulations at room temperature
复制标题
DOI：
10.1110/ps.041167605
复制
发表时间：
2005-03-01
期刊：
影响因子：
8
通讯作者：
Bowie, JU
中科院分区：
文献类型：
--
作者：
Faham, S;Boulting, GL;Bowie, JU
我们以前表明，高质量的晶体的细菌视紫红质（bR）盐盐杆菌可以获得从双胞形成DMPC/CHAPSO混合物在37 degreesC。由于许多膜蛋白在这种高温下对于结晶不够稳定，我们测试了双胞方法是否可以在较低温度下应用。在这里，我们表明，bR可以在室温下结晶使用两种不同的bicele-forming组合物：DMPC/CHAPSO和DTPC/CHAPSO。在室温下生长的DTPC/CHAPSO晶体基本上与先前的孪晶相同：空间群P2（1），晶胞尺寸为a = 44.7埃，B = 108.7埃，c = 55.8埃，β = 113.6度。室温下的DMPC/CHAPSO晶体是非孪晶的，属于空间群C222（1），具有以下晶胞尺寸：a = 44.7埃，B = 102.5埃，c = 128.2埃。bR蛋白在两种晶体形式中包装成几乎相同的层，但层堆叠不同。新的非孪生晶体形式为以前未解析的CHAPSO分子提供了清晰的密度，该分子插入层内的蛋白质亚基之间。在室温下生长晶体的能力显著地扩展了双胞结晶的适用性。
We showed previously that high-quality crystals of bacteriorhodopsin (bR) from Halobacterium salinarum can be obtained from bicelle-forming DMPC/CHAPSO mixtures at 37degreesC. As many membrane proteins are not sufficiently stable for crystallization at this high temperature, we tested whether the bicelle method could be applied at a lower temperature. Here we show that bR can be crystallized at room temperature using two different bicelle-forming compositions: DMPC/CHAPSO and DTPC/CHAPSO. The DTPC/CHAPSO crystals grown at room temperature are essentially identical to the previous, twinned crystals: space group P2(1) with unit cell dimensions of a = 44.7 Angstrom, b = 108.7 Angstrom, c = 55.8 Angstrom, beta = 113.6degrees. The room-temperature DMPC/CHAPSO crystals are untwinned, however, and belong to space group C222(1) with the following unit cell dimensions: a = 44.7 Angstrom, b = 102.5 Angstrom, c = 128.2 Angstrom. The bR protein packs into almost identical layers in the two crystal forms, but the layers stack differently. The new untwinned crystal form yielded clear density for a previously unresolved CHAPSO molecule inserted between protein subunits within the layers. The ability to grow crystals at room temperature significantly expands the applicability of bicelle crystallization.