X-ray Structure of Bacteriorhodopsin at 2.5 Angstroms from Microcrystals Grown in Lipidic Cubic Phases

• Published in: Science (American Association for the Advancement of Science) Vol. 277; no. 5332; pp. 1676 - 1681
• Main Authors: Pebay-Peyroula, Eva, Rummel, Gabriele, Rosenbusch, Jurg P., Landau, Ehud M.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 12.09.1997; American Association for the Advancement of Science
• Subjects: Analytical, structural and metabolic biochemistry; Bacteriorhodopsin; Bacteriorhodopsins - chemistry; Biological and medical sciences; Crystal structure; Crystallization; Crystallography; Crystallography, X-Ray - methods; Crystals; Cubic crystals; Cytoplasm - chemistry; Electron density; Fundamental and applied biological sciences. Psychology; Glycerides; Halobacterium - chemistry; Hydrogen Bonding; Hydrogen bonds; Lipids; Models, Molecular; Molecules; Non metallic chromoproteins, photoproteins; Protein Conformation; Protein Structure, Secondary; Proteins; Proton Pumps; Protons; Retinaldehyde - chemistry; Schiff Bases; Synchrotrons; Water; Water channels; Bacteriorhodopsin; Halobacterium salinarum; Membrane protein; Membrane pump; Molecular structure; Archaeobacteria; Halobacteriales; Proton; Bacteria; Halobacteriaceae; Photoprotein; X ray diffraction
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.277.5332.1676

Lipidic cubic phases provide a continuous three-dimensional bilayer matrix that facilitates nucleation and growth of bacteriorhodopsin microcrystals. The crystals diffract x-rays isotropically to 2.0 angstroms. The structure of this light-driven proton pump was solved at a resolution of 2.5 angstroms by molecular replacement, using previous results from electron crystallographic studies as a model. The earlier structure was generally confirmed, but several differences were found, including loop conformations and side chain residues. Eight water molecules are now identified experimentally in the proton pathway. These findings reveal the constituents of the proton translocation pathway in the ground state.