gh fragHAR: towards ab initio quantum-crystallographic X-ray structure refinement for polypeptides and proteins By scripts.iucr.org Published On :: 2020-01-17 The first ab initio aspherical structure refinement against experimental X-ray structure factors for polypeptides and proteins using a fragmentation approach to break up the protein into residues and solvent, thereby speeding up quantum-crystallographic Hirshfeld atom refinement (HAR) calculations, is described. It it found that the geometric and atomic displacement parameters from the new fragHAR method are essentially unchanged from a HAR on the complete unfragmented system when tested on dipeptides, tripeptides and hexapeptides. The largest changes are for the parameters describing H atoms involved in hydrogen-bond interactions, but it is shown that these discrepancies can be removed by including the interacting fragments as a single larger fragment in the fragmentation scheme. Significant speed-ups are observed for the larger systems. Using this approach, it is possible to perform a highly parallelized HAR in reasonable times for large systems. The method has been implemented in the TONTO software. Full Article text
gh Structural insights into conformational switching in latency-associated peptide between transforming growth factor β-1 bound and unbound states By scripts.iucr.org Published On :: 2020-02-06 Transforming growth factor β-1 (TGFβ-1) is a secreted signalling protein that directs many cellular processes and is an attractive target for the treatment of several diseases. The primary endogenous activity regulatory mechanism for TGFβ-1 is sequestration by its pro-peptide, latency-associated peptide (LAP), which sterically prohibits receptor binding by caging TGFβ-1. As such, recombinant LAP is promising as a protein-based therapeutic for modulating TGFβ-1 activity; however, the mechanism of binding is incompletely understood. Comparison of the crystal structure of unbound LAP (solved here to 3.5 Å resolution) with that of the bound complex shows that LAP is in a more open and extended conformation when unbound to TGFβ-1. Analysis suggests a mechanism of binding TGFβ-1 through a large-scale conformational change that includes contraction of the inter-monomer interface and caging by the `straight-jacket' domain that may occur in partnership through a loop-to-helix transition in the core jelly-roll fold. This conformational change does not appear to include a repositioning of the integrin-binding motif as previously proposed. X-ray scattering-based modelling supports this mechanism and reveals possible orientations and ensembles in solution. Although native LAP is heavily glycosylated, solution scattering experiments show that the overall folding and flexibility of unbound LAP are not influenced by glycan modification. The combination of crystallography, solution scattering and biochemical experiments reported here provide insight into the mechanism of LAP sequestration of TGFβ-1 that is of fundamental importance for therapeutic development. Full Article text
gh The resolution revolution in cryoEM requires high-quality sample preparation: a rapid pipeline to a high-resolution map of yeast fatty acid synthase By scripts.iucr.org Published On :: 2020-01-25 Single-particle electron cryo-microscopy (cryoEM) has undergone a `resolution revolution' that makes it possible to characterize megadalton (MDa) complexes at atomic resolution without crystals. To fully exploit the new opportunities in molecular microscopy, new procedures for the cloning, expression and purification of macromolecular complexes need to be explored. Macromolecular assemblies are often unstable, and invasive construct design or inadequate purification conditions and sample-preparation methods can result in disassembly or denaturation. The structure of the 2.6 MDa yeast fatty acid synthase (FAS) has been studied by electron microscopy since the 1960s. Here, a new, streamlined protocol for the rapid production of purified yeast FAS for structure determination by high-resolution cryoEM is reported. Together with a companion protocol for preparing cryoEM specimens on a hydrophilized graphene layer, the new protocol yielded a 3.1 Å resolution map of yeast FAS from 15 000 automatically picked particles within a day. The high map quality enabled a complete atomic model of an intact fungal FAS to be built. Full Article text
gh Estimation of high-order aberrations and anisotropic magnification from cryo-EM data sets in RELION-3.1 By scripts.iucr.org Published On :: 2020-02-11 Methods are presented that detect three types of aberrations in single-particle cryo-EM data sets: symmetrical and antisymmetrical optical aberrations and magnification anisotropy. Because these methods only depend on the availability of a preliminary 3D reconstruction from the data, they can be used to correct for these aberrations for any given cryo-EM data set, a posteriori. Using five publicly available data sets, it is shown that considering these aberrations improves the resolution of the 3D reconstruction when these effects are present. The methods are implemented in version 3.1 of the open-source software package RELION. Full Article text
gh Structure of the MICU1–MICU2 heterodimer provides insights into the gatekeeping threshold shift By scripts.iucr.org Published On :: 2020-02-27 Mitochondrial calcium uptake proteins 1 and 2 (MICU1 and MICU2) mediate mitochondrial Ca2+ influx via the mitochondrial calcium uniporter (MCU). Its molecular action for Ca2+ uptake is tightly controlled by the MICU1–MICU2 heterodimer, which comprises Ca2+ sensing proteins which act as gatekeepers at low [Ca2+] or facilitators at high [Ca2+]. However, the mechanism underlying the regulation of the Ca2+ gatekeeping threshold for mitochondrial Ca2+ uptake through the MCU by the MICU1–MICU2 heterodimer remains unclear. In this study, we determined the crystal structure of the apo form of the human MICU1–MICU2 heterodimer that functions as the MCU gatekeeper. MICU1 and MICU2 assemble in the face-to-face heterodimer with salt bridges and methionine knobs stabilizing the heterodimer in an apo state. Structural analysis suggests how the heterodimer sets a higher Ca2+ threshold than the MICU1 homodimer. The structure of the heterodimer in the apo state provides a framework for understanding the gatekeeping role of the MICU1–MICU2 heterodimer. Full Article text
gh High-resolution cryo-EM reconstructions in the presence of substantial aberrations By scripts.iucr.org Published On :: 2020-03-26 Here, an analysis is performed of how uncorrected antisymmetric aberrations, such as coma and trefoil, affect cryo-EM single-particle reconstruction (SPR) results, and an analytical formula quantifying information loss owing to their presence is inferred that explains why Fourier-shell coefficient-based statistics may report significantly overestimated resolution if these aberrations are not fully corrected. The analysis is validated with reference-based aberration refinement for two cryo-EM SPR data sets acquired with a 200 kV microscope in the presence of coma exceeding 40 µm, and 2.3 and 2.7 Å reconstructions for 144 and 173 kDa particles, respectively, were obtained. The results provide a description of an efficient approach for assessing information loss in cryo-EM SPR data acquired in the presence of higher order aberrations, and address inconsistent guidelines regarding the level of aberrations that is acceptable in cryo-EM SPR experiments. Full Article text
gh Structures of substrate- and product-bound forms of a multi-domain copper nitrite reductase shed light on the role of domain tethering in protein complexes By scripts.iucr.org Published On :: 2020-04-25 Copper-containing nitrite reductases (CuNiRs) are found in all three kingdoms of life and play a major role in the denitrification branch of the global nitrogen cycle where nitrate is used in place of dioxygen as an electron acceptor in respiratory energy metabolism. Several C- and N-terminal redox domain tethered CuNiRs have been identified and structurally characterized during the last decade. Our understanding of the role of tethered domains in these new classes of three-domain CuNiRs, where an extra cytochrome or cupredoxin domain is tethered to the catalytic two-domain CuNiRs, has remained limited. This is further compounded by a complete lack of substrate-bound structures for these tethered CuNiRs. There is still no substrate-bound structure for any of the as-isolated wild-type tethered enzymes. Here, structures of nitrite and product-bound states from a nitrite-soaked crystal of the N-terminal cupredoxin-tethered enzyme from the Hyphomicrobium denitrificans strain 1NES1 (Hd1NES1NiR) are provided. These, together with the as-isolated structure of the same species, provide clear evidence for the role of the N-terminal peptide bearing the conserved His27 in water-mediated anchoring of the substrate at the catalytic T2Cu site. Our data indicate a more complex role of tethering than the intuitive advantage for a partner-protein electron-transfer complex by narrowing the conformational search in such a combined system. Full Article text
gh Visualization of protein crystals by high-energy phase-contrast X-ray imaging By scripts.iucr.org Published On :: 2019-10-31 For the extraction of the best possible X-ray diffraction data from macromolecular crystals, accurate positioning of the crystals with respect to the X-ray beam is crucial. In addition, information about the shape and internal defects of crystals allows the optimization of data-collection strategies. Here, it is demonstrated that the X-ray beam available on the macromolecular crystallography beamline P14 at the high-brilliance synchrotron-radiation source PETRA III at DESY, Hamburg, Germany can be used for high-energy phase-contrast microtomography of protein crystals mounted in an optically opaque lipidic cubic phase matrix. Three-dimensional tomograms have been obtained at X-ray doses that are substantially smaller and on time scales that are substantially shorter than those used for diffraction-scanning approaches that display protein crystals at micrometre resolution. Adding a compound refractive lens as an objective to the imaging setup, two-dimensional imaging at sub-micrometre resolution has been achieved. All experiments were performed on a standard macromolecular crystallography beamline and are compatible with standard diffraction data-collection workflows and apparatus. Phase-contrast X-ray imaging of macromolecular crystals could find wide application at existing and upcoming low-emittance synchrotron-radiation sources. Full Article text
gh Extending the scope of coiled-coil crystal structure solution by AMPLE through improved ab initio modelling By scripts.iucr.org Published On :: 2020-02-25 The phase problem remains a major barrier to overcome in protein structure solution by X-ray crystallography. In recent years, new molecular-replacement approaches using ab initio models and ideal secondary-structure components have greatly contributed to the solution of novel structures in the absence of clear homologues in the PDB or experimental phasing information. This has been particularly successful for highly α-helical structures, and especially coiled-coils, in which the relatively rigid α-helices provide very useful molecular-replacement fragments. This has been seen within the program AMPLE, which uses clustered and truncated ensembles of numerous ab initio models in structure solution, and is already accomplished for α-helical and coiled-coil structures. Here, an expansion in the scope of coiled-coil structure solution by AMPLE is reported, which has been achieved through general improvements in the pipeline, the removal of tNCS correction in molecular replacement and two improved methods for ab initio modelling. Of the latter improvements, enforcing the modelling of elongated helices overcame the bias towards globular folds and provided a rapid method (equivalent to the time requirements of the existing modelling procedures in AMPLE) for enhanced solution. Further, the modelling of two-, three- and four-helical oligomeric coiled-coils, and the use of full/partial oligomers in molecular replacement, provided additional success in difficult and lower resolution cases. Together, these approaches have enabled the solution of a number of parallel/antiparallel dimeric, trimeric and tetrameric coiled-coils at resolutions as low as 3.3 Å, and have thus overcome previous limitations in AMPLE and provided a new functionality in coiled-coil structure solution at lower resolutions. These new approaches have been incorporated into a new release of AMPLE in which automated elongated monomer and oligomer modelling may be activated by selecting `coiled-coil' mode. Full Article text
gh Insight into the role of pre-assembly and desolvation in crystal nucleation: a case of p-nitrobenzoic acid By scripts.iucr.org Published On :: 2019-09-18 As one of the most important phenomena in crystallization, the crystal nucleation process has always been the focus of research. In this work, influences of pre-assembly species and the desolvation process on the crystal nucleation process were studied. p-Nitrobenzoic acid (PNBA) was taken as a model compound to investigate the relationship between solution chemistry and nucleation kinetics in seven different solvents. One unsolvated form and four solvates of PNBA were obtained and one of the solvates was newly discovered. The nucleation behaviours and nucleation kinetics of PNBA in the seven solvents were studied and analyzed. Density functional theory (DFT) and solvation energy calculation were adopted to evaluate the strength of solute–solvent interactions. Vibrational spectroscopy combined with molecular simulation was applied to reveal the pre-assembly species in the solution. Based on these results, a comprehensive understanding of the relationship between molecular structure, crystal structure, solution chemistry and nucleation dynamics was proposed and discussed. It was found that the structural similarity between solution chemistry and crystal structure, the interaction between specific sites and the overall strength of solvation will jointly affect the nucleation process. Full Article text
gh High-energy-resolution inelastic X-ray scattering spectrometer at beamline 30-ID of the Advanced Photon Source By scripts.iucr.org Published On :: 2020-04-06 Inelastic X-ray scattering is a powerful and versatile technique for studying lattice dynamics in materials of scientific and technological importance. In this article, the design and capabilities of the momentum-resolved high-energy-resolution inelastic X-ray spectrometer (HERIX) at beamline 30-ID of the Advanced Photon Source are reported. The instrument operates at 23.724 keV and has an energy resolution of 1.3–1.7 meV. It can accommodate momentum transfers of up to 72 nm−1, at a typical X-ray flux of 4.5 × 109 photons s−1 meV−1 at the sample. A suite of in situ sample environments are provided, including high pressure, static magnetic fields and uniaxial strains, all at high or cryogenic temperatures. Full Article text
gh Linearly polarized X-ray fluorescence computed tomography based on a Thomson scattering light source: a Monte Carlo study By scripts.iucr.org Published On :: 2020-04-06 A Thomson scattering X-ray source can provide quasi-monochromatic, continuously energy-tunable, polarization-controllable and high-brightness X-rays, which makes it an excellent tool for X-ray fluorescence computed tomography (XFCT). In this paper, we examined the suppression of Compton scattering background in XFCT using the linearly polarized X-rays and the implementation feasibility of linearly polarized XFCT based on this type of light source, concerning the influence of phantom attenuation and the sampling strategy, its advantage over K-edge subtraction computed tomography (CT), the imaging time, and the potential pulse pile-up effect by Monte Carlo simulations. A fan beam and pinhole collimator geometry were adopted in the simulation and the phantom was a polymethyl methacrylate cylinder inside which were gadolinium (Gd)-loaded water solutions with Gd concentrations ranging from 0.2 to 4.0 wt%. Compared with the case of vertical polarization, Compton scattering was suppressed by about 1.6 times using horizontal polarization. An accurate image of the Gd-containing phantom was successfully reconstructed with both spatial and quantitative identification, and good linearity between the reconstructed value and the Gd concentration was verified. When the attenuation effect cannot be neglected, one full cycle (360°) sampling and the attenuation correction became necessary. Compared with the results of K-edge subtraction CT, the contrast-to-noise ratio values of XFCT were improved by 2.03 and 1.04 times at low Gd concentrations of 0.2 and 0.5 wt%, respectively. When the flux of a Thomson scattering light source reaches 1013 photons s−1, it is possible to finish the data acquisition of XFCT at the minute or second level without introducing pulse pile-up effects. Full Article text
gh High-dynamic-range transmission-mode detection of synchrotron radiation using X-ray excited optical luminescence in diamond By scripts.iucr.org Published On :: 2020-03-13 Enhancement of X-ray excited optical luminescence in a 100 µm-thick diamond plate by introduction of defect states via electron beam irradiation and subsequent high-temperature annealing is demonstrated. The resulting X-ray transmission-mode scintillator features a linear response to incident photon flux in the range 7.6 × 108 to 1.26 × 1012 photons s−1 mm−2 for hard X-rays (15.9 keV) using exposure times from 0.01 to 5 s. These characteristics enable a real-time transmission-mode imaging of X-ray photon flux density without disruption of X-ray instrument operation. Full Article text
gh Comparative study of the around-Fermi electronic structure of 5d metals and metal-oxides by means of high-resolution X-ray emission and absorption spectroscopies By scripts.iucr.org Published On :: 2020-04-14 The composition of occupied and unoccupied electronic states in the vicinity of Fermi energies is vital for all materials and relates to their physical, chemical and mechanical properties. This work demonstrates how the combination of resonant and non-resonant X-ray emission spectroscopies supplemented with theoretical modelling allows for quantitative analysis of electronic states in 5d transition metal and metal-oxide materials. Application of X-rays provides element selectivity that, in combination with the penetrating properties of hard X-rays, allows determination of the composition of electronic states under working conditions, i.e. non-vacuum environment. Tungsten metal and tungsten oxide are evaluated to show the capability to simultaneously assess composition of around-band-gap electronic states as well as the character and magnitude of the crystal field splitting. Full Article text
gh Focusing with saw-tooth refractive lenses at a high-energy X-ray beamline By scripts.iucr.org Published On :: 2020-04-07 The Advanced Photon Source 1-ID beamline, operating in the 40–140 keV X-ray energy range, has successfully employed continuously tunable saw-tooth refractive lenses to routinely deliver beams focused in both one and two dimensions to experiments for over 15 years. The practical experience of implementing such lenses, made of silicon and aluminium, is presented, including their properties, control, alignment, and diagnostic methods, achieving ∼1 µm focusing (vertically). Ongoing development and prospects towards submicrometre focusing at these high energies are also mentioned. Full Article text
gh High-efficiency ultra-precision comparator for d-spacing mapping measurement of silicon By scripts.iucr.org Published On :: 2020-03-13 This article describes a high-efficiency experimental configuration for a self-referenced lattice comparator with a `brush beam' of synchrotron radiation from a bending magnet and two linear position-sensitive photon-counting-type X-ray detectors. The efficiency is more than ten times greater compared with the `pencil-beam' configuration and a pair of zero-dimensional detectors. A solution for correcting the systematic deviation of d-spacing measurements caused by the horizontal non-uniformity of the brush beam is provided. Also, the use of photon-counting-type one-dimensional detectors not only improves the spatial resolution of the measurements remarkably but can also adjust the sample's attitude angles easily. Full Article text
gh Development of an X-ray imaging detector for high-energy X-ray microtomography By journals.iucr.org Published On :: A dedicated X-ray imaging detector for 200 keV high-energy X-ray microtomography was developed to realize high-efficiency high-resolution imaging while keeping the field of view wide. Full Article text
gh A high-power, high-repetition-rate THz source for pump–probe experiments at Linac Coherent Light Source II By journals.iucr.org Published On :: Full Article text
gh High-performance Python for crystallographic computing By scripts.iucr.org Published On :: 2019-07-24 The Python programming language, combined with the numerical computing library NumPy and the scientific computing library SciPy, has become the de facto standard for scientific computing in a variety of fields. This popularity is mainly due to the ease with which a Python program can be written and executed (easy syntax, dynamical typing, no compilation etc.), coupled with the existence of a large number of specialized third-party libraries that aim to lift all the limitations of the raw Python language. NumPy introduces vector programming, improving execution speeds, whereas SciPy brings a wealth of highly optimized and reliable scientific functions. There are cases, however, where vector programming alone is not sufficient to reach optimal performance. This issue is addressed with dedicated compilers that aim to translate Python code into native and statically typed code with support for the multi-core architectures of modern processors. In the present article it is shown how these approaches can be efficiently used to tackle different problems, with increasing complexity, that are relevant to crystallography: the 2D Laue function, scattering from a strained 2D crystal, scattering from 3D nanocrystals and, finally, diffraction from films and multilayers. For each case, detailed implementations and explanations of the functioning of the algorithms are provided. Different Python compilers (namely NumExpr, Numba, Pythran and Cython) are used to improve performance and are benchmarked against state-of-the-art NumPy implementations. All examples are also provided as commented and didactic Python (Jupyter) notebooks that can be used as starting points for crystallographers curious to enter the Python ecosystem or wishing to accelerate their existing codes. Full Article text
gh Efficient data extraction from neutron time-of-flight spin-echo raw data By scripts.iucr.org Published On :: 2019-08-29 Neutron spin-echo spectrometers with a position-sensitive detector and operating with extended time-of-flight-tagged wavelength frames are able to collect a comprehensive set of data covering a large range of wavevector and Fourier time space with only a few instrumental settings in a quasi-continuous way. Extracting all the information contained in the raw data and mapping them to a suitable physical space in the most efficient way is a challenge. This article reports algorithms employed in dedicated software, DrSpine (data reduction for spin echo), that achieves this goal and yields reliable representations of the intermediate scattering function S(Q, t) independent of the selected `binning'. Full Article text
gh High-viscosity sample-injection device for serial femtosecond crystallography at atmospheric pressure By scripts.iucr.org Published On :: 2019-10-17 A sample-injection device has been developed at SPring-8 Angstrom Compact Free-Electron Laser (SACLA) for serial femtosecond crystallography (SFX) at atmospheric pressure. Microcrystals embedded in a highly viscous carrier are stably delivered from a capillary nozzle with the aid of a coaxial gas flow and a suction device. The cartridge-type sample reservoir is easily replaceable and facilitates sample reloading or exchange. The reservoir is positioned in a cooling jacket with a temperature-regulated water flow, which is useful to prevent drastic changes in the sample temperature during data collection. This work demonstrates that the injector successfully worked in SFX of the human A2A adenosine receptor complexed with an antagonist, ZM241385, in lipidic cubic phase and for hen egg-white lysozyme microcrystals in a grease carrier. The injection device has also been applied to many kinds of proteins, not only for static structural analyses but also for dynamics studies using pump–probe techniques. Full Article text
gh PtychoShelves, a versatile high-level framework for high-performance analysis of ptychographic data By scripts.iucr.org Published On :: 2020-03-13 Over the past decade, ptychography has been proven to be a robust tool for non-destructive high-resolution quantitative electron, X-ray and optical microscopy. It allows for quantitative reconstruction of the specimen's transmissivity, as well as recovery of the illuminating wavefront. Additionally, various algorithms have been developed to account for systematic errors and improved convergence. With fast ptychographic microscopes and more advanced algorithms, both the complexity of the reconstruction task and the data volume increase significantly. PtychoShelves is a software package which combines high-level modularity for easy and fast changes to the data-processing pipeline, and high-performance computing on CPUs and GPUs. Full Article text
gh Application of a high-throughput microcrystal delivery system to serial femtosecond crystallography By scripts.iucr.org Published On :: 2020-03-25 Microcrystal delivery methods are pivotal in the use of serial femtosecond crystallography (SFX) to resolve the macromolecular structures of proteins. Here, the development of a novel technique and instruments for efficiently delivering microcrystals for SFX are presented. The new method, which relies on a one-dimensional fixed-target system that includes a microcrystal container, consumes an extremely low amount of sample compared with conventional two-dimensional fixed-target techniques at ambient temperature. This novel system can deliver soluble microcrystals without highly viscous carrier media and, moreover, can be used as a microcrystal growth device for SFX. Diffraction data collection utilizing this advanced technique along with a real-time visual servo scan system has been successfully demonstrated for the structure determination of proteinase K microcrystals at 1.85 Å resolution. Full Article text
gh Significant texture improvement in single-crystalline-like materials on low-cost flexible metal foils through growth of silver thin films By journals.iucr.org Published On :: Single-crystalline-like thin films composed of crystallographically aligned grains are a new prototype of 2D materials developed recently for low-cost and high-performance flexible electronics as well as second-generation high-temperature superconductors. In this work, significant texture improvement in single-crystalline-like materials is achieved through growth of a 330 nm-thick silver layer. Full Article text
gh High-resolution phonon energy shift measurements with the inelastic neutron spin echo technique By journals.iucr.org Published On :: An energy resolution of <10 µeV for the measurement of phonon energy change is achieved with the inelastic neutron spin echo technique on a conventional neutron triple-axis spectrometer. Full Article text
gh Disorder in La1−xBa1+xGaO4−x/2 ionic conductor: resolving the pair distribution function through insight from first-principles modeling By journals.iucr.org Published On :: Ba excess in LaBaGaO4 triggers ionic conductivity together with structural disorder. A direct correlation is found between the density functional theory model energy and the pair distribution function fit residual. Full Article text
gh Accurate high-resolution single-crystal diffraction data from a Pilatus3 X CdTe detector By journals.iucr.org Published On :: Detailed analysis of the high-flux deficiencies of pixel-array detectors leads to a protocol for the measurement of structure factors of unprecedented accuracy even for inorganic materials, and this significantly advances the prospects for experimental electron-density investigations. Full Article text
gh Dark-field electron holography as a recording of crystal diffraction in real space: a comparative study with high-resolution X-ray diffraction for strain analysis of MOSFETs By journals.iucr.org Published On :: A detailed theoretical and experimental comparison of dark-field electron holography (DFEH) and high-resolution X-ray diffraction (HRXRD) is performed. Both techniques are being applied to measure elastic strain in an array of transistors and the role of the geometric phase is emphasized. Full Article text
gh High-resolution crystal structures of Escherichia coli FtsZ bound to GDP and GTP By scripts.iucr.org Published On :: 2020-02-05 Bacterial cytokinesis is mediated by the Z-ring, which is formed by the prokaryotic tubulin homolog FtsZ. Recent data indicate that the Z-ring is composed of small patches of FtsZ protofilaments that travel around the bacterial cell by treadmilling. Treadmilling involves a switch from a relaxed (R) state, favored for monomers, to a tense (T) conformation, which is favored upon association into filaments. The R conformation has been observed in numerous monomeric FtsZ crystal structures and the T conformation in Staphylococcus aureus FtsZ crystallized as assembled filaments. However, while Escherichia coli has served as a main model system for the study of the Z-ring and the associated divisome, a structure has not yet been reported for E. coli FtsZ. To address this gap, structures were determined of the E. coli FtsZ mutant FtsZ(L178E) with GDP and GTP bound to 1.35 and 1.40 Å resolution, respectively. The E. coli FtsZ(L178E) structures both crystallized as straight filaments with subunits in the R conformation. These high-resolution structures can be employed to facilitate experimental cell-division studies and their interpretation in E. coli. Full Article text
gh New research reveals our galaxy is much larger than we thought By insider.si.edu Published On :: Mon, 06 Jul 2009 17:50:22 +0000 New measurements show that the Milky Way is bigger and more massive than previous data suggested, putting us on equal footing with our neighbor. Specifically, the Milky Way is 15 percent larger in size and contains 50 percent more mass. That is the cosmic equivalent of a 5-foot-5, 140-pound man suddenly bulking up to the size of a 6-foot-3, 210-pound NFL linebacker. The post New research reveals our galaxy is much larger than we thought appeared first on Smithsonian Insider. Full Article Research News Science & Nature Space astronomy astrophysics galaxies Milky Way Smithsonian Astrophysical Observatory
gh Cosmic “baby photos” of distant solar systems lend insight as to how planets form By insider.si.edu Published On :: Wed, 19 Aug 2009 23:52:40 +0000 New observations by the Smithsonian’s Submillimeter Array, a radio telescope atop Mauna Kea in Hawaii, are shedding light on planet formation. The array provides sharp views by combining eight antennas into the equivalent of a single, large telescope. It can resolve details as small as a dime seen from seven miles away. The post Cosmic “baby photos” of distant solar systems lend insight as to how planets form appeared first on Smithsonian Insider. Full Article Research News Science & Nature Space astronomy astrophysics planets Smithsonian Astrophysical Observatory
gh Smithsonian receives giant squid caught in the Gulf of Mexico By insider.si.edu Published On :: Thu, 24 Sep 2009 14:47:11 +0000 The giant squid was collected during a 60-day scientific study in which NOAA scientists were studying the availability and diversity of sperm whale prey. The squid was caught in a trawl net pulled behind a research vessel at a depth of more than 1,500 feet. The post Smithsonian receives giant squid caught in the Gulf of Mexico appeared first on Smithsonian Insider. Full Article Animals Marine Science Research News Science & Nature Caribbean conservation biology National Museum of Natural History new acquisitions squid
gh Ancient star discovered through patience and clever use of technology By insider.si.edu Published On :: Fri, 05 Mar 2010 19:41:02 +0000 Finding this stellar relic wasn’t easy. It is 60,000 times dimmer than the faintest star visible to the unaided eye. The team also had to distinguish it from many surrounding stars that aren’t so old. Just like an archaeological dig, the hunt succeeded through a combination of patience and clever use of technology. The post Ancient star discovered through patience and clever use of technology appeared first on Smithsonian Insider. Full Article Research News Science & Nature Space astronomy astrophysics bees Smithsonian Astrophysical Observatory technology
gh Eighty-thousand bark beetles enter National Museum of Natural History collections By insider.si.edu Published On :: Tue, 23 Mar 2010 14:12:21 +0000 The Stephen L. Wood collection brings the collection of bark beetles held in the Natural History Museum’s Department of Entomology to an impressive 180,000 specimens, making it one of the most extensive collections in world. The post Eighty-thousand bark beetles enter National Museum of Natural History collections appeared first on Smithsonian Insider. Full Article Animals Research News Science & Nature conservation biology insects National Museum of Natural History new acquisitions
gh Pulverized planet dust might lie around double stars By insider.si.edu Published On :: Tue, 24 Aug 2010 17:07:13 +0000 NASA’s Spitzer Space Telescope recently spotted a surprisingly large amount of dust around three mature, close-orbiting star pairs. Where did the dust come from? Astronomers say it might be the aftermath of tremendous planetary collisions. The post Pulverized planet dust might lie around double stars appeared first on Smithsonian Insider. Full Article Research News Science & Nature astronomy astrophysics planets Smithsonian Astrophysical Observatory
gh Earth’s highest coastal mountain range moved 1,367 miles in 170 million years By insider.si.edu Published On :: Thu, 23 Sep 2010 12:47:46 +0000 Using the ancient magnetic field recorded in these rocks, a Smithsonian research group revealed Santa Marta’s 2,200-kilometer journey from northern Peru to its modern position on the Caribbean coast of Colombia during the past 170 million years. The post Earth’s highest coastal mountain range moved 1,367 miles in 170 million years appeared first on Smithsonian Insider. Full Article Research News Science & Nature Caribbean Colombia geology prehistoric rocks & minerals South America Tropical Research Institute
gh Newly discovered Madagascar spider spins largest, toughest webs on record By insider.si.edu Published On :: Sat, 02 Oct 2010 10:42:40 +0000 Darwin's bark spider cast giant webs across streams, rivers and lakes, suspending the web’s orb above water and attaching it to plants on each riverbank. Bridgelines of these water-spanning webs have been measured as long as 25 meters. The post Newly discovered Madagascar spider spins largest, toughest webs on record appeared first on Smithsonian Insider. Full Article Animals Research News Science & Nature biodiversity insects National Museum of Natural History spiders
gh Newly discovered massive galaxy cluster wins heavyweight title By insider.si.edu Published On :: Fri, 15 Oct 2010 18:58:03 +0000 "This galaxy cluster wins the heavyweight title. It's among the most massive clusters ever found at this distance," said Mark Brodwin, a Smithsonian astronomer at the Harvard-Smithsonian Center for Astrophysics. The post Newly discovered massive galaxy cluster wins heavyweight title appeared first on Smithsonian Insider. Full Article Research News Science & Nature Space astronomy astrophysics galaxies Smithsonian Astrophysical Observatory
gh Harvard-Smithsonian astrophysicist discovers new method to weigh some distant stars By insider.si.edu Published On :: Mon, 08 Nov 2010 17:55:48 +0000 New research by astrophysicist David Kipping has revealed that in some special cases, a star can be weighed directly. Such a star must have a planet orbiting it with a moon orbiting the planet. The post Harvard-Smithsonian astrophysicist discovers new method to weigh some distant stars appeared first on Smithsonian Insider. Full Article Research News Science & Nature Space astronomy astrophysics geology Smithsonian Astrophysical Observatory
gh Astronomers discover merging star systems that might explode By insider.si.edu Published On :: Tue, 16 Nov 2010 18:14:36 +0000 Today, researchers who found the first hypervelocity stars escaping the Milky Way announced that their search also turned up a dozen double-star systems. Half of those are merging and might explode as supernovae in the astronomically near future. The post Astronomers discover merging star systems that might explode appeared first on Smithsonian Insider. Full Article Research News Science & Nature Space astronomy astrophysics Smithsonian Astrophysical Observatory supernova
gh Snowflake Study through Photomicrography, 1890 By insider.si.edu Published On :: Tue, 18 Jan 2011 19:53:36 +0000 Snowflake Study through Photomicrography, 1890 Wilson A. Bentley became fascinated with the crystalline structure of individual snowflakes on his parent’s Vermont farm. By adapting a […] The post Snowflake Study through Photomicrography, 1890 appeared first on Smithsonian Insider. Full Article Science & Nature Snapshot photography Smithsonian Institution Archives
gh From chewing tough insects to soft fruit, bat teeth are highly specialized By insider.si.edu Published On :: Tue, 22 Feb 2011 15:55:06 +0000 They found that the molars of fruit-eating species had sharp outer edges that likely allow them to pierce tough fruit skin and pulp... By contrast, the molars of insect-eating species were less complex, possibly because of their smoother shearing surfaces. The post From chewing tough insects to soft fruit, bat teeth are highly specialized appeared first on Smithsonian Insider. Full Article Animals Science & Nature bats endangered species insects mammals Tropical Research Institute
gh Surprise! Rare animals caught on camera at “Smithsonian WILD!” By insider.si.edu Published On :: Thu, 24 Feb 2011 19:18:18 +0000 Smithsonian WILD! a new Web site from the Smithsonian Conservation Biology Institute designed to showcase the use of motion-triggered 'camera traps' by Smithsonian researchers, has been launched at the Web address siwild.si.edu. The post Surprise! Rare animals caught on camera at “Smithsonian WILD!” appeared first on Smithsonian Insider. Full Article Animals Research News Science & Nature biodiversity camera traps conservation biology endangered species mammals Smithsonian Conservation Biology Institute Smithsonian's National Zoo
gh X-ray stripes in exploded star may reveal highest energies of cosmic rays produced in our Galaxy By insider.si.edu Published On :: Mon, 28 Mar 2011 14:00:54 +0000 The discovery of a pattern of X-ray “stripes” in the remains of an exploded star may provide the first direct evidence that a cosmic event […] The post X-ray stripes in exploded star may reveal highest energies of cosmic rays produced in our Galaxy appeared first on Smithsonian Insider. Full Article Research News Science & Nature astronomy astrophysics Center for Astrophysics | Harvard & Smithsonian Chandra X-Ray Observatory Smithsonian Astrophysical Observatory supernova
gh Don’t pick a fight with a eunuch spider. It has nothing to lose By insider.si.edu Published On :: Thu, 07 Apr 2011 15:27:31 +0000 In a recent study of the mating behavior of these Asian spiders, researchers found that 87.5 percent of males had both palps amputated during copulation. The post Don’t pick a fight with a eunuch spider. It has nothing to lose appeared first on Smithsonian Insider. Full Article Animals Research News Science & Nature biodiversity insects National Museum of Natural History spiders
gh Astronomers in distant future might still deduce the Big Bang origin of the Universe By insider.si.edu Published On :: Mon, 18 Apr 2011 15:15:42 +0000 Astronomers of the future won't have to take the Big Bang on faith. With careful measurements and clever analysis, they can find the subtle evidence outlining the history of the universe. The post Astronomers in distant future might still deduce the Big Bang origin of the Universe appeared first on Smithsonian Insider. Full Article Research News Science & Nature Space astronomy biodiversity Center for Astrophysics | Harvard & Smithsonian galaxies Smithsonian Astrophysical Observatory
gh Stunning high-resolution NASA images available online for public exhibits By insider.si.edu Published On :: Thu, 05 May 2011 13:06:38 +0000 The National Aeronautics and Space Administration has made available to the public a new online collection of images that capture the excitement of planetary exploration and the journey to understand the origin and evolution of the solar system. The post Stunning high-resolution NASA images available online for public exhibits appeared first on Smithsonian Insider. Full Article Research News Science & Nature Space astronomy astrophysics Center for Astrophysics | Harvard & Smithsonian Smithsonian Astrophysical Observatory
gh New supernova remnant lights up! By insider.si.edu Published On :: Thu, 09 Jun 2011 15:06:10 +0000 In 1987, light from an exploding star in a neighboring galaxy, the Large Magellanic Cloud, reached Earth. Named Supernova 1987A, it was the closest supernova explosion witnessed in almost 400 years, allowing astronomers to study it in unprecedented detail as it evolves. The post New supernova remnant lights up! appeared first on Smithsonian Insider. Full Article Research News Science & Nature Space astronomy astrophysics Center for Astrophysics | Harvard & Smithsonian Smithsonian Astrophysical Observatory supernova
gh Lofty experiments with gliding ants reveals secrets of their unusual flight By insider.si.edu Published On :: Mon, 13 Jun 2011 19:17:26 +0000 One of the most challenging aspects of this research is simply studying these insects as they are falling, says Yanoviak, a tropical arthropod ecologist at the University of Arkansas, Little Rock. Small body size, rapid descent, and the long distances that they can fall, make accurate data taking a challenge. The post Lofty experiments with gliding ants reveals secrets of their unusual flight appeared first on Smithsonian Insider. Full Article Animals Research News Science & Nature insects South America Tropical Research Institute
gh Exoplanet aurora: An out-of-this-world sight By insider.si.edu Published On :: Thu, 21 Jul 2011 16:29:19 +0000 New research shows that aurorae on distant "hot Jupiters" could be 100-1000 times brighter than Earthly aurorae. They also would ripple from equator to poles (due to the planet's proximity to any stellar eruptions), treating the entire planet to an otherworldly spectacle. The post Exoplanet aurora: An out-of-this-world sight appeared first on Smithsonian Insider. Full Article Research News Science & Nature astronomy astrophysics Center for Astrophysics | Harvard & Smithsonian planets Smithsonian Astrophysical Observatory