2qto
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(New page: 200px<br /><applet load="2qto" size="350" color="white" frame="true" align="right" spinBox="true" caption="2qto, resolution 3.201Å" /> '''An anisotropic mode...)
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Revision as of 11:29, 23 January 2008
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An anisotropic model for potassium channel KcsA
Overview
We report a normal-mode method for anisotropic refinement of, membrane-protein structures, based on a hypothesis that the global, near-native-state disordering of membrane proteins in crystals follows, low-frequency normal modes. Thus, a small set of modes is sufficient to, represent the anisotropic thermal motions in X-ray crystallographic, refinement. By applying the method to potassium channel KcsA at 3.2 A, we, obtained a structural model with an improved fit with the diffraction, data. Moreover, the improved electron density maps allowed for large, structural adjustments for 12 residues in each subunit, including the, rebuilding of 3 missing side chains. Overall, the anisotropic KcsA, structure at 3.2 A was systematically closer to a 2.0 A KcsA structure, especially in the selectivity filter. Furthermore, the anisotropic thermal, ellipsoids from the refinement revealed functionally relevant structural, flexibility. We expect this method to be a valuable tool for structural, refinement of many membrane proteins with moderate-resolution diffraction, data.
About this Structure
2QTO is a Single protein structure of sequence from Streptomyces lividans with as ligand. Full crystallographic information is available from OCA.
Reference
Normal-mode refinement of anisotropic thermal parameters for potassium channel KcsA at 3.2 A crystallographic resolution., Chen X, Poon BK, Dousis A, Wang Q, Ma J, Structure. 2007 Aug;15(8):955-62. PMID:17698000
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