1qhj
From Proteopedia
(New page: 200px<br /><applet load="1qhj" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qhj, resolution 1.90Å" /> '''X-RAY STRUCTURE OF B...) |
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| - | [[Image:1qhj.jpg|left|200px]]<br /><applet load="1qhj" size=" | + | [[Image:1qhj.jpg|left|200px]]<br /><applet load="1qhj" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1qhj, resolution 1.90Å" /> | caption="1qhj, resolution 1.90Å" /> | ||
'''X-RAY STRUCTURE OF BACTERIORHODOPSIN GROWN IN LIPIDIC CUBIC PHASES'''<br /> | '''X-RAY STRUCTURE OF BACTERIORHODOPSIN GROWN IN LIPIDIC CUBIC PHASES'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Bacteriorhodopsin (bR) from Halobacterium salinarum is a | + | BACKGROUND: Bacteriorhodopsin (bR) from Halobacterium salinarum is a proton pump that converts the energy of light into a proton gradient that drives ATP synthesis. The protein comprises seven transmembrane helices and in vivo is organized into purple patches, in which bR and lipids form a crystalline two-dimensional array. Upon absorption of a photon, retinal, which is covalently bound to Lys216 via a Schiff base, is isomerized to a 13-cis,15-anti configuration. This initiates a sequence of events - the photocycle - during which a proton is transferred from the Schiff base to Asp85, followed by proton release into the extracellular medium and reprotonation from the cytoplasmic side. RESULTS: The structure of bR in the ground state was solved to 1.9 A resolution from non-twinned crystals grown in a lipidic cubic phase. The structure reveals eight well-ordered water molecules in the extracellular half of the putative proton translocation pathway. The water molecules form a continuous hydrogen-bond network from the Schiff-base nitrogen (Lys216) to Glu194 and Glu204 and includes residues Asp85, Asp212 and Arg82. This network is involved both in proton translocation occurring during the photocycle, as well as in stabilizing the structure of the ground state. Nine lipid phytanyl moieties could be modeled into the electron-density maps. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis of single crystals demonstrated the presence of four different charged lipid species. CONCLUSIONS: The structure of protein, lipid and water molecules in the crystals represents the functional entity of bR in the purple membrane of the bacteria at atomic resolution. Proton translocation from the Schiff base to the extracellular medium is mediated by a hydrogen-bond network that involves charged residues and water molecules. |
==About this Structure== | ==About this Structure== | ||
| - | 1QHJ 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 RET and PH1 as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1QHJ 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=RET:'>RET</scene> and <scene name='pdbligand=PH1:'>PH1</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QHJ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Belrhali, H.]] | [[Category: Belrhali, H.]] | ||
| - | [[Category: Landau, E | + | [[Category: Landau, E M.]] |
[[Category: Menzel, C.]] | [[Category: Menzel, C.]] | ||
[[Category: Nollert, P.]] | [[Category: Nollert, P.]] | ||
[[Category: Pebay-Peyroula, E.]] | [[Category: Pebay-Peyroula, E.]] | ||
| - | [[Category: Rosenbusch, J | + | [[Category: Rosenbusch, J P.]] |
[[Category: Royant, A.]] | [[Category: Royant, A.]] | ||
[[Category: PH1]] | [[Category: PH1]] | ||
| Line 30: | Line 30: | ||
[[Category: retinal protein]] | [[Category: retinal protein]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:39:37 2008'' |
Revision as of 12:39, 21 February 2008
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X-RAY STRUCTURE OF BACTERIORHODOPSIN GROWN IN LIPIDIC CUBIC PHASES
Overview
BACKGROUND: Bacteriorhodopsin (bR) from Halobacterium salinarum is a proton pump that converts the energy of light into a proton gradient that drives ATP synthesis. The protein comprises seven transmembrane helices and in vivo is organized into purple patches, in which bR and lipids form a crystalline two-dimensional array. Upon absorption of a photon, retinal, which is covalently bound to Lys216 via a Schiff base, is isomerized to a 13-cis,15-anti configuration. This initiates a sequence of events - the photocycle - during which a proton is transferred from the Schiff base to Asp85, followed by proton release into the extracellular medium and reprotonation from the cytoplasmic side. RESULTS: The structure of bR in the ground state was solved to 1.9 A resolution from non-twinned crystals grown in a lipidic cubic phase. The structure reveals eight well-ordered water molecules in the extracellular half of the putative proton translocation pathway. The water molecules form a continuous hydrogen-bond network from the Schiff-base nitrogen (Lys216) to Glu194 and Glu204 and includes residues Asp85, Asp212 and Arg82. This network is involved both in proton translocation occurring during the photocycle, as well as in stabilizing the structure of the ground state. Nine lipid phytanyl moieties could be modeled into the electron-density maps. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis of single crystals demonstrated the presence of four different charged lipid species. CONCLUSIONS: The structure of protein, lipid and water molecules in the crystals represents the functional entity of bR in the purple membrane of the bacteria at atomic resolution. Proton translocation from the Schiff base to the extracellular medium is mediated by a hydrogen-bond network that involves charged residues and water molecules.
About this Structure
1QHJ is a Single protein structure of sequence from Halobacterium salinarum with and as ligands. Full crystallographic information is available from OCA.
Reference
Protein, lipid and water organization in bacteriorhodopsin crystals: a molecular view of the purple membrane at 1.9 A resolution., Belrhali H, Nollert P, Royant A, Menzel C, Rosenbusch JP, Landau EM, Pebay-Peyroula E, Structure. 1999 Aug 15;7(8):909-17. PMID:10467143
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