Crystallization of bacteriorhodopsin from bicelle formulations at room temperatureFaham, S., Boulting, G.L., Massey, E.A., Yohannan, S., Yang, D., Bowie, J.U.
(2005) Protein Sci. 14: 836-840
- PubMed: 15689517
- DOI: 10.1110/ps.041167605
- PubMed Abstract:
We showed previously that high-quality crystals of bacteriorhodopsin (bR) from Halobacterium salinarum can be obtained from bicelle-forming DMPC/CHAPSO mixtures at 37 degrees C. As many membrane proteins are not sufficiently stable for crystallizatio ...
We showed previously that high-quality crystals of bacteriorhodopsin (bR) from Halobacterium salinarum can be obtained from bicelle-forming DMPC/CHAPSO mixtures at 37 degrees C. 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 P21 with unit cell dimensions of a = 44.7 A, b = 108.7 A, c = 55.8 A, beta = 113.6 degrees . 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 A, b = 102.5 A, c = 128.2 A. 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.
Department of Chemistry and Biochemistry, UCLA-DOE Center for Genomics and Proteomics, Molecular Biology Institute, University of California, Los Angeles, California 90095-1570, USA.