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| Helix deformation is coupled to vectorial proton transport in the photocycle of bacteriorhodopsin |
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| Author(s): Royant A, Edman K, Ursby T, Pebay-Peyroula E, Landau EM, Neutze R |
| Source: NATURE Volume: 406 Issue: 6796 Pages: 645-648 Published: AUG 10 2000 |
| Times Cited: 152 References: 30 |
| Abstract: A wide variety of mechanisms are used to generate a protonmotive potential across cell membranes, a function lying at the heart of bioenergetics. Bacteriorhodopsin, the simplest known proton pump(1), provides a paradigm for understanding this process. Here we report, at 2.1 Angstrom resolution, the structural changes in bacteriorhodopsin immediately preceding the primary proton transfer event in its photocycle. The early structural rearrangements(2) propagate from the protein's core towards the extracellular surface, disrupting the network of hydrogen-bonded water molecules that stabilizes helix C in the ground state. Concomitantly, a bend of this helix enables the negatively charged(3) primary proton acceptor, Asp 85, to approach closer to the positively charged primary proton donor, the Schiff base. The primary proton transfer event would then neutralize these two groups, cancelling their electrostatic attraction and facilitating a relaxation of helix C to a less strained geometry. Reprotonation of the Schiff base by Asp 85 would thereby be impeded, ensuring vectorial proton transport. Structural rearrangements also occur near the protein's surface, aiding proton release to the extracellular medium. |
| Document Type: Article |
| Language: English |
| Reprint Address: Landau, EM (reprint author), Univ Basel, Biozentrum, Klingelbergstr 70, CH-4056 Basel, Switzerland |
Addresses:
1. Univ Basel, Biozentrum, CH-4056 Basel, Switzerland
2. Univ Grenoble 1, Inst Biol Struct, CEA, CNRS,UMR 5075, F-38027 Grenoble 1, France
3. Uppsala Univ, Biomed Ctr, Dept Biochem, S-75123 Uppsala, Sweden
4. European Synchrotron Radiat Facil, F-38043 Grenoble, France |
| Publisher: MACMILLAN PUBLISHERS LTD, PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND |
| Subject Category: Multidisciplinary Sciences |
| IDS Number: 342PF |
| ISSN: 0028-0836 |
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