ALBERT

Description: The three-dimensional structures of macromolecules and their complexes are mainly elucidated by X-ray protein crystallography. A major limitation of this method is access to high-quality crystals, which is necessary to ensure X-ray diffraction extends to sufficiently large scattering angles and hence yields information of sufficiently high resolution with which to solve the crystal structure. The observation that crystals with reduced unit-cell volumes and tighter macromolecular packing often produce higher-resolution Bragg peaks suggests that crystallographic resolution for some macromolecules may be limited not by their heterogeneity, but by a deviation of strict positional ordering of the crystalline lattice. Such displacements of molecules from the ideal lattice give rise to a continuous diffraction pattern that is equal to the incoherent sum of diffraction from rigid individual molecular complexes aligned along several discrete crystallographic orientations and that, consequently, contains more information than Bragg peaks alone. Although such continuous diffraction patterns have long been observed--and are of interest as a source of information about the dynamics of proteins--they have not been used for structure determination. Here we show for crystals of the integral membrane protein complex photosystem II that lattice disorder increases the information content and the resolution of the diffraction pattern well beyond the 4.5-angstrom limit of measurable Bragg peaks, which allows us to phase the pattern directly. Using the molecular envelope conventionally determined at 4.5 angstroms as a constraint, we obtain a static image of the photosystem II dimer at a resolution of 3.5 angstroms. This result shows that continuous diffraction can be used to overcome what have long been supposed to be the resolution limits of macromolecular crystallography, using a method that exploits commonly encountered imperfect crystals and enables model-free phasing.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ayyer, Kartik -- Yefanov, Oleksandr M -- Oberthur, Dominik -- Roy-Chowdhury, Shatabdi -- Galli, Lorenzo -- Mariani, Valerio -- Basu, Shibom -- Coe, Jesse -- Conrad, Chelsie E -- Fromme, Raimund -- Schaffer, Alexander -- Dorner, Katerina -- James, Daniel -- Kupitz, Christopher -- Metz, Markus -- Nelson, Garrett -- Xavier, Paulraj Lourdu -- Beyerlein, Kenneth R -- Schmidt, Marius -- Sarrou, Iosifina -- Spence, John C H -- Weierstall, Uwe -- White, Thomas A -- Yang, Jay-How -- Zhao, Yun -- Liang, Mengning -- Aquila, Andrew -- Hunter, Mark S -- Robinson, Joseph S -- Koglin, Jason E -- Boutet, Sebastien -- Fromme, Petra -- Barty, Anton -- Chapman, Henry N -- P41GM103393/GM/NIGMS NIH HHS/ -- P41RR001209/RR/NCRR NIH HHS/ -- R01 GM095583/GM/NIGMS NIH HHS/ -- R01 GM097463/GM/NIGMS NIH HHS/ -- U54 GM094599/GM/NIGMS NIH HHS/ -- England -- Nature. 2016 Feb 11;530(7589):202-6. doi: 10.1038/nature16949.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Free-Electron Laser Science, DESY, 22607 Hamburg, Germany. ; Department of Physics, University of Hamburg, 22761 Hamburg, Germany. ; School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA. ; Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA. ; Department of Physics, Arizona State University, Tempe, Arizona 85287, USA. ; Physics Department, University of Wisconsin, Milwaukee, Wisconsin 53211, USA. ; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Hellas, GR-70013 Crete, Greece. ; Linac Coherent Light Source, Stanford Linear Accelerator Center (SLAC), National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA. ; Centre for Ultrafast Imaging, 22607 Hamburg, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26863980" target="_blank"〉PubMed〈/a〉