XXI Congress and General Assembly
Osaka, Japan, August 23-31
|Left: Tomitake Tsukihara, Chair of the Local Organizing Committee. Centre left: Yasuhiko Fujii, Japan, Chair of the International Program Committee. Centre right: David Sayre. Right: David Sayre receives 2008 Ewald Prize at Opening Ceremony.|
|Left: IUCr President Yujii Ohashi and Yukako Ohashi. Right: Newly elected IUCr President Sine Larsen and Henk Schenk|
|Left: The conference took place at the Grand Cube, Osaka. Right: Downtown Osaka.|
|Left: Entertainment at Opening Ceremony. Right: Photograph exhibit celebrating the 60th anniversary of the IUCr.|
Power to the proteins powder
Rena MargiolakiRena Margiolaki (ESRF, France) presented a summary of the emerging field of protein powder diffraction. She reviewed early work by Bob Von Dreele on Met myoglobin, a new structure of human insulin and complexes of hen egg white lysozyme with glucosamine oligimers. She described the feasibility of using powder diffraction to solve protein structures by molecular replacement and initial results obtaining molecular envelopes using heavy atom derivatives. She described phase changes observed during cryocooling, new insulin phases and the solution of a urate oxidase tetramer with more than 10,000 atoms by molecular replacement. R. Von Dreele
Nanostructures on Surfaces
Cristian MocutaThe physical properties of nanostructures differ from those of larger assemblies because large surface to volume ratios alter energetics and internal structure. In the past, X-ray beams were too large to probe single nanostructures, forcing interpretation of the scattering from averages of many nanostructures. Cristian Mocuta (ESRD, France) described how X-ray scattering studies using synchrotron radiation with beams sufficiently small to probe individual nanostructures are providing valuable new insights into these materials. S. Gruner
Refinement and Modelling of Complex Mineral Structure (KN36)
Roberta ObertiRoberta Oberti (U of Pavia, Italy) demonstrated how complex mineral systems, like the amphiboles, with highly coupled multi-site, multi-species substitutions can be characterised. Their secrets can be unravelled by a combination of diffraction, spectroscopy and crystal-chemical modelling. The latter allows not only a deeper understanding of observed particularities, but also possesses predictive power, for instance with respect to the occurrence and distribution of species such as H, Li, Be or B which are otherwise barely detectable. Wulf Depmeier
Lasers, Jet Streams, Turkish Spiders and Powder Power (MS09)
New technologies are becoming available to study micron-sized crystallites and multiple crystal clusters. Tiny crystallites can be studied one by one, as polycrystals or as powders. The formation of a nucleus of a crystal can also be studied by diffraction techniques. Bob von Dreele (USA) has monitored the transition from solution to amorphous to single micro crystals of lysozyme (Figure 1). New X-ray lasers may have sufficient photons per 10 fsec pulse to obtain diffraction patterns from a single protein molecule before radiation destroys the sample. Alternatively, if the photons per pulse are low, a 10x10x10 cluster of proteins may yield the necessary intensity statistics. David Shapiro (USA) showed the first ever protein powder diffraction from a stream of tiny crystallites of photosystem I (PSI) that were measured at the Hamburg FLASH Facility using gas jets and soft X-rays. The wavelength used did not lead to absorption with these 'micro-jet' sample thicknesses and the powder pattern had well resolved lines. Sebastian Basso (Switzerland) reported successful determination of protein envelopes and secondary structure features at ~4 Å resolution using MIR phasing at ESRF. Yoichiroh Hosokawa (Japan) described the use of a fsec infra-red laser to either cut a fragment of a crystal from a cluster without thermal damage or to irradiate a solution with laser pulses to promote nucleation. The Session chair was startled to learn that the technique has been used to crystallize membrane proteins. Pinar Batat (Turkey) examined the silks from many varieties of Turkish spiders with electron microscopy, SWAXS, XRD and tensile strength measurements. Optimal structural properties were found in silk from well nourished spiders in quality habitats. John R. Helliwell
Crystal Chiral Chemistry, New Ideas, New Instruments (MS14)Crystallographic analysis allows the study of the chirality of a molecular assembly and its functionality. In this symposium a wide range of topics involving chirality were discussed, including growth conditions, properties, the computational chemistry of chiral crystals and their use in absolute asymmetric synthesis. Of particular interest was a description of the Universal Chiroptical Spectrophotometer (UCS), being built by R. Kuroda and co-workers (Japan) that will permit artifact-free CD measurements for crystalline powder samples. Ichiro Hisaki
The Interface between CryoEM and Crystallography (MS22)
Session on the interface between CryoEM and CrystallographyIn this microsymposium Steve Ludtke (Baylor College of Medicine) showed Electron Microscope (EM) reconstructions in which all main-chain secondary structure and many side-chain atoms were resolved, and a movie of domain movement in a fatty acid synthetase. Tom Blundell (UK) expressed surprise at how well a structure could be modelled into a 4 Angstrom resolution map. Steve noted that unlike crystallographic maps, CryoEM maps have very reliable phases and less-reliable amplitudes, so map errors are qualitatively different.
Structure determination of the epilson15 virus by cryoEM (Wen Jiang, USA) required collection of 3000 images and 1 million cpu-hours to calculate the reconstruction (10 days per cycle on a supercomputer cluster). Ed Egelman (USA) presented structural results using his helical processing technique and observed that individual subunits in fibrous structures are highly conserved, but quaternary structure interactions between subunits diverge. Atsunori Oshima (Japan) described a gap junction in a 2-layer 2D crystal, and mutational analysis indicating that a plug at the entrance to the pore consists of N-terminal residues. Elizabeth Villa (USA) has a novel method to fit EM maps using restrained molecular dynamics. She showed a movie in which parts of a ribosomal structure move large distances to fit an EM map. The method will be available as a module of the program VMD. Cathy Lawson (USA) described deposition and archiving of EM maps at the EM databank (emdatabank.org) Wah Chiu and Cathy Lawson
Virus Structure and Antiviral Strategies (MS29)
Structure of the Ebola virus glycoprotein PDBid = 3CSY in complex with a neutralizing antibody from a human survivor. The structure reveals a putative receptor-binding site sequestered in a bowl of the chalice formed by three GP1 subunits (colored in shades of blue), wrapped around by three GP2 fusion subunits (colored white). The antibody fragment (colored yellow) bridges the GP1 and GP2 subunits and is specific for the prefusion viral surface conformation of GP2. (J. E. Lee, M. L. Fusco, A. J. Hessell, W. B. Oswald, D. R. Burton, and E. O. Saphire. (2008). Structure of the Ebola virus glycoprotein bound to an antibody from a human survivor. Nature, 454, 177-182.)Crystal structures of medically and economically important viruses revealed how these smallest and simplest biological entities survive and replicate, fostering the development of strategies to prevent animal and human disease. Peter Kwong (USA) presented a structure of HIV gp120 complexed with a neutralizing antibody Fab fragment, which showed it only binds with heavy chain, and that HIV gp120, and perhaps HIV as a whole, only has one 'attack' point for neutralizing antibodies. The identified epitope has been disguised in a recombinant protein with the aim of using this protein as a vaccine. Nuria Verdaguer (Spain) presented structures of viral RNA-dependent RNA polymerases from birnavirus and foot and mouth disease virus with bound substrates. Felix Rey (France) also talked about birna viruses but focused on the capsid and evolutionary relationships, noting that picobirna viruses are not structurally related to birnaviruses.
The sole Ebola virus surface protein, GP, which is post-translationally cleaved to give GP1 and GP2, was described by Jeff Lee (USA). It was crystallized with a monoclonal antibody Fab fragment from a human survivor of the Kitwit Ebola outbreak in Zambia. Like HIV, gp120 is predicted to be almost entirely covered by glycosylation. Rolf Hilgenfeld (Germany) pointed out that all recently (re)-emerging viruses (avian influenza, SARS, Marburg, and others) are RNA viruses and advocated the need for studying all animal viruses, to be prepared for the emergence of human variants. If lead compounds can be developed against them, several years will have been gained when a virus does emerge. He presented structures of several RNA virus proteases and ongoing work to develop inhibitors for them. Funding for this will have to be at least partially public, as big pharma will not be financially interested. J. Johnson and M. J. van Raaij
Advanced Electron Microscopy (MS34)This microsymposium highlighted applications and instrumental developments in electron microscopy with an emphasis on high resolution imaging in the Transmission and Scanning Transmission Electron Microscope (TEM and STEM). Kazuo Suenaga (Japan) presented spectacular images at close to atomic resolution of conformational changes in retinal molecules encapsulated within carbon nanotubes. Susanne Stemmer (USA) discussed possible origins of the 'Stobbs Factor' in Annular Dark Field STEM imaging and showed how careful experimental calibration of the detector response function and the use of a frozen phonon model for calculation of ADF intensity enabled quantitative imaging. Andrew Bleloch (UK) discussed recent work at the UK SuperSTEM facility showing the location of gold impurity atoms in silicon nanowires and the use of discrete tomography from a limited projection set of ADF images to determine morphology in metallic nanoparticles. Osamu Kamimura (Japan) described the development of a novel microscope, operating at 30kV, optimized for recording coherent electron diffraction patterns for use in phase retrieval/phase extension algorithms. Gianluigi Botton (Canada) provided an overview of the use of aberration corrected TEM and STEM imaging coupled to EELS in the study of catalysts and pyrochlore structures that show magnetic frustration. A. I. Kirkland and R. Holmestad
MS36 Huge and Complex Viruses and Proteins
Assembly of rice dwarf virus PDBid = 1UF2. (Toshihiro Omura)This symposium featured a fascinating animation of the assembly process of the rice dwarf virus (T. Omura, Japan). It is one of the largest viruses for which the three-dimensional structure has been determined. The architecture of a virus infecting archea (A. Goulet, France) was shown to be different from most other known viruses. It resembles the organization found in nucleosomes. Other topics covered were reconstruction of ion channels using single particle analysis (Chikara Sato, Japan), the structure of the giant muscle protein titin (M. Wilmanns, Germany) and Holliday junction resolvases (D. Suck, Germany). M. R. N. Murthy and K. Iwasaki
Charge Flipping and Relaxation in Real Space (MS62)A microsymposium on real space direct methods focused on algorithmic advances. While nonconvexity of the various phase retrieval problems presented in the session remains a sensitive issue, new algorithms or variants of existing algorithms make it possible to achieve better convergence profiles and to avoid local minima. Specific topics included developing algorithms for recovering protein structure from signals with very low photon counts (D. Saldin, USA), alternating thresholding/projection algorithms in the spirit of charge flipping methods, forcing both the known magnitude data in reciprocal space and a degree of sparseness in real space (S. Marchesini, USA), projection/reflection relaxation schemes for phase retrieval in diffraction imaging (R. Luke, USA), algorithms for handling inverse problems via subgradient projection techniques (I. Yamada, USA), and a solution to the phase problem for surface X-ray imaging (I. P. Lyman, USA). P. L. Combettes
Co-crystals: Theory, Synthesis and Use (MS66)Describing 'Multi-component solids in crystal engineering', Gautam R. Desiraju (India) noted that early descriptions of multi-component molecular crystals pre-date the modern concept of crystal engineering. He described the introduction of reliable chemical information into engineered crystals with supramolecular synthons that permit discrimination between likely and less likely structural products and his visions of future directions within the fields of chemical crystallography and crystal engineering. Christer B. Aakeröy (USA), 'From a molecular dating agency to successful co-crystal synthesis', focused on co-crystal synthesis as an analogue of molecular synthesis, including 'supramolecular yield' and 'supramolecular selectivity'. He stressed that co-crystal chemistry should not be restricted to systems that prove to be amenable to single-crystal X-ray structural analysis and presented research utilising a diverse range of tunable, site-specific intermolecular interactions for programmed design of co-crystals containing two or three different molecular components, as well as larger supramolecular systems such as molecular capsules. William Jones (UK) illustrated a broad range of multi-component systems, with emphasis on pharmaceutical products. He showed that solvent-assisted mechanical grinding permits comprehensive screening of multi-component chemical systems and can yield co-crystals that are different from those obtained using solution techniques. An example of efficacious co-crystallization is the improved stability of caffeine afforded by co-crystallization with oxalic acid.
Carol P. Brock (USA) presented a detailed analysis of a two-component molecular system, ordered layers of triphenylphosphine oxide with disordered layers of hydrogen-bonded cyclohexane dialcohol molecules. The system resisted a satisfactory solution until improved instrumentation became available for data collection. One particularly intriguing aspect of the study was an apparent relationship between the degree of order in the co-crystal and the solvent used for crystallization, which might go on to yield interesting information regarding the role of solvent intervention in the crystallization process. In a talk combining in situ co-crystallization with Raman spectroscopy, Michael Kirchner (Germany) described experimental procedures for co-crystallization of the smallest molecules that are usually liquid or gas under ambient conditions. Attempted crystallizations of these compounds yielded only microcrystalline products. The value of spectroscopic techniques was stressed for these cases to ascertain whether or not co-crystallization had actually occurred, and an in situ installation of a probe for Raman spectroscopy was highlighted. The session was complemented by a keynote lecture by Michael J. Zaworotko (USA) that provided further visions and examples for development in this active research area. Maio Du and Andrew D. Bond
Diffuse Scattering in Partially Disordered Systems (MS77)Richard Welberry (Australia) reviewed a wide-range of diffuse scattering phenomena in many different systems, and demonstrated the use of single-crystal X-ray diffuse scattering to extract local correlations in disordered molecular systems. Monte Carlo simulations employing inter- and intramolecular spring constants reproduced all of the key features in the experimental patterns. Miwako Takahashi (Japan) measured magnetic diffuse scattering at KENS in Pt-rich PtMn alloys (the new ABC6 structure) and identified diffuse incommensurate satellites with intermediate-range incommensurate spin-density waves induced by Fermi-surface nesting. Sonia Francoual (USA) identified diffuse-scattering signatures of phason diffuse scattering in X-ray patterns of icosahedral Zn-X-Sc (X = Co, Ag, Mg) quasicrystals, and successfully measured the phason elastic coefficients (for zero phason-phonon coupling) that were insightfully related to the electronic structure and composition and atomic radius of element X. Thomas Weber (Switzerland) demonstrated novel 3D PDF analysis techniques for extracting local structure information from quasicrystal diffuse scattering patterns. Clever data reduction strategies that isolate one type of feature at a time in Q-space greatly simplify the preparation and interpretation of the PDF. In photochromic cuprous-halide nanocrystals embedded in a glassy boro-alumino-silicate matrix, doped with Cd and Sn, Sylvio Haas (Germany) showed that the analysis of multi-resonant small-angle X-ray scattering data can recover complicated core/shell/matrix composition profiles. H. Abe and C. Branton
Membrane Protein Crystallization (MS78)Although the number of membrane protein structure determinations is growing, each one still requires extensive individual study and membrane protein crystallization continues to be a major bottleneck This session focused on efforts to improve technology for general applications including the design of new amphiphiles, new concepts for crystallization and experiments with lipid composition. The presentations highlighted recent determinations of physiologically important membrane protein structures, such as the Ca-pump, squid rhodopsin and a human gap junction protein (S. Maeda, Japan). The final presentation, by A. May, USA, concerned a new practical approach, based on microfluidics and showed how diffraction patterns can be obtained in situ without any crystal handling. C. Toyoshima (Japan) and T. Kouyama (Japan) described all the steps that allowed them to obtain highly diffracting crystals of Ca-ATPase and squid rhodopsin respectively and the critical role played by lipids selection. E. Pebay-Peyroula and S. Yoshikawa
New Neutron Sources (MS81)This microsymposium showcased current developments in neutron sources and their impact on crystallography. It included reports from representatives of each of the three sources that have started produce neutrons in the last two years; the OPAL reactor (Brendan Kennedy, Australia), J-PARC (Yujiro Ikeda, Japan) and the SNS (Ian Anderson, USA). Among the highlights were the world-record power of SNS, the high spatial resolution of the super-HRPD at J-PARC and the high speed of the Wombat diffractometer at OPAL. We also heard about two sources where cold neutron research facilities are being established; the HANARO reactor, (Chang Hee Lee, Korea) and the HFIR reactor (Ian Anderson). Finally, we learned of plans for the development of Europe's next generation neutron source, the ESS-Scandinavia project (Christian Vettier, Sweden). Several important themes emerged during discussion including:
• Are there enough powerful neutron sources to meet the current needs?
• Is there sufficient and timely provision for future neutron sources to satisfy projected future needs?
• How well do current developments in neutron scattering infrastructure meet the changing needs of the community?
• How can outreach activities be improved to attract more users and to promote advances in neutron capability?
• How do we ensure that new sources combine with existing sources to provide competitive service for the community, without dilution of stakeholder support?
• How can research selection programmes be managed to optimise access to the most appropriate user research facilities, particularly when sources are co-located?
These last two points have particular relevance for JAEA in Tokai and for Oak Ridge National Laboratories, where spallation sources are being commissioned at the same campus, and managed by the same organizations, as existing long-serving research reactors.
The session also provided a forum for announcement of the formation of the Asia-Oceania Neutron Scattering Assn, which is intended to co-ordinate of the activities of the neutron scattering societies of the member countries (currently Australia, India, Japan, Korea, Taiwan) and to liaise with the regional neutron scattering societies of Europe and North America on international activities. Shane Kennedy and Yukio Noda