Structural highlights
Function[BACR_HALSA] Light-driven proton pump. Publication Abstract from PubMedBacteriorhodopsin (bR) provides light-driven vectorial proton transport across a cell membrane. Creation of electrochemical potential at the membrane is a universal step in energy transformation in a cell. Published atomic crystallographic models of early intermediate states of bR show a significant difference between them, and conclusions about pumping mechanisms have been contradictory. Here, we present a quantitative high-resolution crystallographic study of conformational changes in bR induced by X-ray absorption. It is shown that X-ray doses that are usually accumulated during data collection for intermediate-state studies are sufficient to significantly alter the structure of the protein. X-ray-induced changes occur primarily in the active site of bR. Structural modeling showed that X-ray absorption triggers retinal isomerization accompanied by the disappearance of electron densities corresponding to the water molecule W402 bound to the Schiff base. It is demonstrated that these and other X-ray-induced changes may mimic functional conformational changes of bR leading to misinterpretation of the earlier obtained X-ray crystallographic structures of photointermediates. X-ray-Radiation-Induced Changes in Bacteriorhodopsin Structure.,Borshchevskiy VI, Round ES, Popov AN, Buldt G, Gordeliy VI J Mol Biol. 2011 Apr 21. PMID:21530535[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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