1f4z
From Proteopedia
(New page: 200px<br /><applet load="1f4z" size="450" color="white" frame="true" align="right" spinBox="true" caption="1f4z, resolution 1.80Å" /> '''BACTERIORHODOPSIN-M ...) |
|||
| Line 1: | Line 1: | ||
| - | [[Image:1f4z.jpg|left|200px]]<br /><applet load="1f4z" size=" | + | [[Image:1f4z.jpg|left|200px]]<br /><applet load="1f4z" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1f4z, resolution 1.80Å" /> | caption="1f4z, resolution 1.80Å" /> | ||
'''BACTERIORHODOPSIN-M PHOTOINTERMEDIATE STATE OF THE E204Q MUTANT AT 1.8 ANGSTROM RESOLUTION'''<br /> | '''BACTERIORHODOPSIN-M PHOTOINTERMEDIATE STATE OF THE E204Q MUTANT AT 1.8 ANGSTROM RESOLUTION'''<br /> | ||
==Overview== | ==Overview== | ||
| - | In order to understand how isomerization of the retinal drives | + | In order to understand how isomerization of the retinal drives unidirectional transmembrane ion transport in bacteriorhodopsin, we determined the atomic structures of the BR state and M photointermediate of the E204Q mutant, to 1.7 and 1.8 A resolution, respectively. Comparison of this M, in which proton release to the extracellular surface is blocked, with the previously determined M in the D96N mutant indicates that the changes in the extracellular region are initiated by changes in the electrostatic interactions of the retinal Schiff base with Asp85 and Asp212, but those on the cytoplasmic side originate from steric conflict of the 13-methyl retinal group with Trp182 and distortion of the pi-bulge of helix G. The structural changes suggest that protonation of Asp85 initiates a cascade of atomic displacements in the extracellular region that cause release of a proton to the surface. The progressive relaxation of the strained 13-cis retinal chain with deprotonated Schiff base, in turn, initiates atomic displacements in the cytoplasmic region that cause the intercalation of a hydrogen-bonded water molecule between Thr46 and Asp96. This accounts for the lowering of the pK(a) of Asp96, which then reprotonates the Schiff base via a newly formed chain of water molecules that is extending toward the Schiff base. |
==About this Structure== | ==About this Structure== | ||
| - | 1F4Z is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Halobacterium_salinarum Halobacterium salinarum] with LI1, SQU and RET as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1F4Z is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Halobacterium_salinarum Halobacterium salinarum] with <scene name='pdbligand=LI1:'>LI1</scene>, <scene name='pdbligand=SQU:'>SQU</scene> and <scene name='pdbligand=RET:'>RET</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1F4Z OCA]. |
==Reference== | ==Reference== | ||
| Line 13: | Line 13: | ||
[[Category: Halobacterium salinarum]] | [[Category: Halobacterium salinarum]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Cartailler, J | + | [[Category: Cartailler, J P.]] |
| - | [[Category: Lanyi, J | + | [[Category: Lanyi, J K.]] |
[[Category: Luecke, H.]] | [[Category: Luecke, H.]] | ||
[[Category: Needleman, R.]] | [[Category: Needleman, R.]] | ||
| - | [[Category: Richter, H | + | [[Category: Richter, H T.]] |
[[Category: Rosengarth, A.]] | [[Category: Rosengarth, A.]] | ||
[[Category: Schobert, B.]] | [[Category: Schobert, B.]] | ||
| Line 35: | Line 35: | ||
[[Category: retinal protein]] | [[Category: retinal protein]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:34:58 2008'' |
Revision as of 10:35, 21 February 2008
|
BACTERIORHODOPSIN-M PHOTOINTERMEDIATE STATE OF THE E204Q MUTANT AT 1.8 ANGSTROM RESOLUTION
Overview
In order to understand how isomerization of the retinal drives unidirectional transmembrane ion transport in bacteriorhodopsin, we determined the atomic structures of the BR state and M photointermediate of the E204Q mutant, to 1.7 and 1.8 A resolution, respectively. Comparison of this M, in which proton release to the extracellular surface is blocked, with the previously determined M in the D96N mutant indicates that the changes in the extracellular region are initiated by changes in the electrostatic interactions of the retinal Schiff base with Asp85 and Asp212, but those on the cytoplasmic side originate from steric conflict of the 13-methyl retinal group with Trp182 and distortion of the pi-bulge of helix G. The structural changes suggest that protonation of Asp85 initiates a cascade of atomic displacements in the extracellular region that cause release of a proton to the surface. The progressive relaxation of the strained 13-cis retinal chain with deprotonated Schiff base, in turn, initiates atomic displacements in the cytoplasmic region that cause the intercalation of a hydrogen-bonded water molecule between Thr46 and Asp96. This accounts for the lowering of the pK(a) of Asp96, which then reprotonates the Schiff base via a newly formed chain of water molecules that is extending toward the Schiff base.
About this Structure
1F4Z is a Single protein structure of sequence from Halobacterium salinarum with , and as ligands. Full crystallographic information is available from OCA.
Reference
Coupling photoisomerization of retinal to directional transport in bacteriorhodopsin., Luecke H, Schobert B, Cartailler JP, Richter HT, Rosengarth A, Needleman R, Lanyi JK, J Mol Biol. 2000 Jul 28;300(5):1237-55. PMID:10903866
Page seeded by OCA on Thu Feb 21 12:34:58 2008
Categories: Halobacterium salinarum | Single protein | Cartailler, J P. | Lanyi, J K. | Luecke, H. | Needleman, R. | Richter, H T. | Rosengarth, A. | Schobert, B. | LI1 | RET | SQU | 7-transmembrane | E204q mutant m state | Haloarchaea | Ion pump | Ion transport | Lipids | Membrane protein | Merohedral twinning | Photocycle intermediate | Photoreceptor | Retinal protein
