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| {{STRUCTURE_2i20| PDB=2i20 | SCENE= }} | | {{STRUCTURE_2i20| PDB=2i20 | SCENE= }} |
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| '''Bacteriorhodopsin/lipid complex, M state of D96A mutant'''
| | ===Bacteriorhodopsin/lipid complex, M state of D96A mutant=== |
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| ==Overview==
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| The X-ray diffraction structure of the non-illuminated D96A bacteriorhodopsin mutant reveals structural changes as far away as 15 A from residue 96, at the retinal, Trp-182, Ala-215, and waters 501, 402, and 401. The Asp-to-Ala side-chain replacement breaks its hydrogen bond with Thr-46, and the resulting separation of the cytoplasmic ends of helices B and C is communicated to the retinal region through a chain of covalent and hydrogen bonds. The unexpected long-range consequences of the D96A mutation include breaking the hydrogen bond between O of Ala-215 and water 501 and the formation of a new hydrogen bond between water molecules 401 and 402 in the extracellular region. Because in the T46V mutant a new water molecule appears at Asp-96 and its hydrogen-bond to Ile-45 replaces Thr-46 as its link to helix B, the separation of helices B and C is smaller than that in D96A, and there are no atomic displacements elsewhere in the protein. Propagation of conformational changes along the chain between the retinal and Thr-46 had been observed earlier in the crystal structures of the D96N and E204Q mutants but in the trapped M state. Consistent with the perturbation of the retinal region in D96A, little change of the Thr-46 region occurs between the non-illuminated and M states of this mutant. It appears that a local perturbation can propagate along a track in both directions between the retinal and the Asp-96/Thr-46 pair, either from photoisomerization of the retinal in the wild-type protein in one case or from the D96A mutation in the other. | | The line below this paragraph, {{ABSTRACT_PUBMED_17002299}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17002299 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17002299}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Retinal protein]] | | [[Category: Retinal protein]] |
| [[Category: Serpentine]] | | [[Category: Serpentine]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 06:58:56 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 06:50:40 2008'' |
