2fkw
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(New page: 200px<br /><applet load="2fkw" size="450" color="white" frame="true" align="right" spinBox="true" caption="2fkw, resolution 2.45Å" /> '''Structure of LH2 fro...)
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Revision as of 08:29, 21 November 2007
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Structure of LH2 from Rps. acidophila crystallized in lipidic mesophases
Overview
The cubic phase or in meso crystallization method is responsible for, almost 40 solved integral membrane protein structures. Most of these are, small and compact proteins. A model for how crystals form by the in meso, method has been proposed that invokes a transition between mesophases. In, light of this model, we speculated that a more hydrated and open, mesophase, of reduced interfacial curvature, would support facile, crystallization of bigger and bulkier proteins. The proposal was explored, here by performing crystallization in the presence of additives that swell, the cubic phase. The additive concentration inducing swelling, as, quantified by small-angle X-ray diffraction, coincided with a, "crystallization window" in which two, very different transmembranal, proteins produced crystals. That the swollen mesophase can grow, structure-grade crystals was proven with one of these, the, light-harvesting II complex. In most regards, the structural details of, the corresponding complex resembled those of crystals grown by the, conventional vapour diffusion method, with some important differences. In, particular, packing density in the in meso-grown crystals was dramatically, higher, more akin to that seen with water-soluble proteins, which accounts, for their enhanced diffracting power. The layered and close in-plane, packing observed has been rationalized in a model for nucleation and, crystal growth by the in meso method that involves swollen mesophases., These results present a rational case for including mesophase-swelling, additives in screens for in meso crystallogenesis. Their use will, contribute to broadening the range of membrane proteins that yield to, structure determination.
About this Structure
2FKW is a Protein complex structure of sequences from Rhodoblastus acidophilus with RG1, BCL and LDA as ligands. Full crystallographic information is available from OCA.
Reference
Room to move: crystallizing membrane proteins in swollen lipidic mesophases., Cherezov V, Clogston J, Papiz MZ, Caffrey M, J Mol Biol. 2006 Apr 14;357(5):1605-18. Epub 2006 Feb 2. PMID:16490208
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