1cwq
From Proteopedia
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| , resolution 2.25Å | |||||||
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| Ligands: | , , , and | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
M INTERMEDIATE STRUCTURE OF THE WILD TYPE BACTERIORHODOPSIN IN COMBINATION WITH THE GROUND STATE STRUCTURE
Overview
The transport of protons across membranes is an important process in cellular bioenergetics. The light-driven proton pump bacteriorhodopsin is the best-characterized protein providing this function. Photon energy is absorbed by the chromophore retinal, covalently bound to Lys 216 via a protonated Schiff base. The light-induced all-trans to 13-cis isomerization of the retinal results in deprotonation of the Schiff base followed by alterations in protonatable groups within bacteriorhodopsin. The changed force field induces changes, even in the tertiary structure, which are necessary for proton pumping. The recent report of a high-resolution X-ray crystal structure for the late M intermediate of a mutant bacteriorhopsin (with Asp 96-->Asn) displays the structure of a proton pathway highly disturbed by the mutation. To observe an unperturbed proton pathway, we determined the structure of the late M intermediate of wild-type bacteriorhodopsin (2.25 A resolution). The cytoplasmic side of our M2 structure shows a water net that allows proton transfer from the proton donor group Asp 96 towards the Schiff base. An enlarged cavity system above Asp 96 is observed, which facilitates the de- and reprotonation of this group by fluctuating water molecules in the last part of the cycle.
About this Structure
1CWQ is a Single protein structure of sequence from Halobacterium salinarum. Full crystallographic information is available from OCA.
Reference
Structural alterations for proton translocation in the M state of wild-type bacteriorhodopsin., Sass HJ, Buldt G, Gessenich R, Hehn D, Neff D, Schlesinger R, Berendzen J, Ormos P, Nature. 2000 Aug 10;406(6796):649-53. PMID:10949308
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