The structure of the Pseudomonas aeruginosa T6SS PldB immunity protein PA5086 is reported at 1.9 Å resolution. Comparison of PA5086 with its homologs PA5087 and PA5088 showed great similarities in sequence and structure, but vast divergences in electrostatic potential surfaces.

A putative open reading frame encoding GTP cyclohydrolase I from Listeria monocytogenes was expressed in a recombinant Escherichia coli strain. The recombinant protein was purified and was confirmed to convert GTP to dihydroneopterin triphosphate (Km = 53 µM; vmax = 180 nmol mg−1 min−1). The protein was crystallized from 1.3 M sodium citrate pH 7.3 and the crystal structure was solved at a resolution of 2.4 Å (Rfree = 0.226) by molecular replacement using human GTP cyclohydrolase I as a template. The protein is a D5-symmetric decamer with ten topologically equivalent active sites. Screening a small library of about 9000 compounds afforded several inhibitors with IC50 values in the low-micromolar range. Several inhibitors had significant selectivity with regard to human GTP cyclohydrolase I. Hence, GTP cyclohydrolase I may be a potential target for novel drugs directed at microbial infections, including listeriosis, a rare disease with high mortality.

The crystallization of amidase, the ultimate enzyme in the Trp-dependent auxin-biosynthesis pathway, from Arabidopsis thaliana was attempted using protein samples with at least 95% purity. Cube-shaped crystals that were assumed to be amidase crystals that belonged to space group I4 (unit-cell parameters a = b = 128.6, c = 249.7 Å) were obtained and diffracted to 3.0 Å resolution. Molecular replacement using structures from the PDB containing the amidase signature fold as search models was unsuccessful in yielding a convincing solution. Using the Sequence-Independent Molecular replacement Based on Available Databases (SIMBAD) program, it was discovered that the structure corresponded to dihydrolipoamide succinyltransferase from Escherichia coli (PDB entry 1c4t), which is considered to be a common crystallization contaminant protein. The structure was refined to an Rwork of 23.0% and an Rfree of 27.2% at 3.0 Å resolution. The structure was compared with others of the same protein deposited in the PDB. This is the first report of the structure of dihydrolipo­amide succinyltransferase isolated without an expression tag and in this novel crystal form.

The crystal structure of MgCoGa2 (magnesium cobalt digallide) was solved by direct methods and refined in two space groups as P21/c (standard choice) and P21/n (non-standard choice). The refined lattice parameters for the standard choice are a = 5.1505 (2), b = 7.2571 (2), c = 8.0264 (3) Å and β = 125.571 (3)°, and for the non-standard choice are a = 5.1505 (2), b = 7.2571 (2), c = 6.5464 (2) Å and β = 94.217 (3)°. All parameters for MgCoGa2 refined to R1 = 0.027 and wR2 = 0.042 using 594 reflections. The crystal structure peculiarities of this compound are discussed. Particular attention has been given to relationships with other similar structures, such as YPd2Si and Fe3C. Crystallographic analysis, together with linear muffin-tin orbital electronic structure calculations, reveals the presence of three-dimensional polyatomic nets with partial covalent bonding between the Ga atoms.

In southeastern Greenland, two rivers of ice named Helheim and Kangerdlugssuaq flow in spurts and starts toward the coast. They are much like any other […]

The post Astrophysical Observatory scientists are monitoring the mysterious movements of glaciers appeared first on Smithsonian Insider.

Scientists from the Smithsonian Migratory Bird Center at the National Zoo have taken blood samples from thousands of birds and mosquitoes in an effort to track the progress of the West Nile Virus in the eastern United States. Come along in this video as Smithsonian scientists net birds living in downtown Washington, D.C., extract small amounts of blood, and then release them back into the "wild."

The post Video: Common birds in Washington, D.C. are helping Smithsonian scientists track intensity of the West Nile Virus appeared first on Smithsonian Insider.

Long before dawn on a recent morning, Katie Milton and a group of stalwart volunteers, each armed with flashlight and compass, spread out into the jungle to take up positions at 35 listening stations marked on maps of the island.

The post Census reveals 1,200 howler monkeys living on Barro Colorado Island appeared first on Smithsonian Insider.

When it comes to brains, is bigger better? Can the tiny brain of a newly hatched spiderling handle problems as adeptly as the brain of a larger adult spider?

The post Tiny, new brains prove just as adept as large, mature brains among tropical orb-web spiders appeared first on Smithsonian Insider.

The anemones—both of which are commonly called Tealia red anemones under the species of Urticina—spawned in late April and early May, just days apart. Henley collected the eggs and sperm from the more than 2,000-gallon tank and put them together in smaller tanks to increase the chances of fertilization. After fertilization, the larvae settled and metamorphosed into a polyp.

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To celebrate a cool Halloween creature--bats--we teamed up with the Smithsonian’s Kristofer Helgen, curator of mammals at the National Museum of Natural History. Here, he answers three commonly asked questions about these winged mammals.

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According to new research by Nick Stone and Avi Loeb (Harvard-Smithsonian Center for Astrophysics), upcoming sky surveys might offer astronomers a way to catch a gorging black hole "in the act."

The post Astronomers seek monster black hole gorging on a buffet of stars appeared first on Smithsonian Insider.

Scientists at the Smithsonian’s National Zoo detected a secondary rise in urinary progesterone levels in the Zoo’s female giant panda Mei Xiang (may-SHONG). This hormone rise indicates that it should be 40 to 50 days before Mei Xiang either gives birth to a cub or comes to the end of a pseudopregnancy, or false pregnancy, which is common in giant pandas.

The post Hormone tests show Mei Xiang, the National Zoo’s female giant panda, may be pregnant appeared first on Smithsonian Insider.

Using the deepest X-ray image ever taken, astronomers found the first direct evidence that massive black holes were common in the early universe. This discovery from NASA's Chandra X-ray Observatory shows that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies.

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Some--birds called wire-tailed manakins, residents of tropical forests in the Americas--are cooperators as well as competitors. They cooperate, forming alliances for a common cause.

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Small monkey groups may win territorial disputes against larger groups because some members of the larger, invading groups avoid aggressive encounters.

The post Members of small monkey groups more likely to fight, researchers find appeared first on Smithsonian Insider.

The young primate seems bright, alert, and increases its activity and independence day by day.

The post Howler monkey born at National Zoo appeared first on Smithsonian Insider.

Smithsonian Conservation Biology Institute scientists and collaborators have found that the island scrub-jay’s population on Santa Cruz Island—its only habitat—is significantly smaller than previously believed […]

The post New count reveals scrub-jay on Santa Cruz Island is among rarest bird species in the U.S. appeared first on Smithsonian Insider.

Using echolocation alone the bats found, identified and captured insects perched motionless and silent on the leaves of plants.

The post Common tropical bat uses echolocation with precision previously considered impossible, new experiments reveal appeared first on Smithsonian Insider.

Out in Montana’s Big Sky Country Dale Greenwalt spends his summers seeking the incredibly tiny and fragile. Armed with a putty knife honed razor-sharp on […]

The post Quality of insect fossils from Montana’s Flathead River astounds scientists appeared first on Smithsonian Insider.

John Kovac of the Harvard-­Smithsonian Center for Astrophysics has been named one of Time Magazine’s 100 most influential people. 

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A newly released study focusing on an extinct species, the Caribbean monk seal (Monachus tropicalis), has revealed just how evolutionarily unique its only two living […]

The post Too valuable to lose: Extinct relative reveals rarity of last two remaining monk seal species appeared first on Smithsonian Insider.

Zombies have been part of popular culture for decades. The living dead rising and taking over the world is a terrifying concept, worthy of Hollywood […]

The post It’s science: zombies already walk among us appeared first on Smithsonian Insider.

Warming temperatures may mean more generations of monarch butterflies in North America during summer months, say scientists who recently finished experiments with monarch caterpillars and […]

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Now here is something to ruminate on. About 85 percent of the methane produced by a cow comes out of its mouth as burps. The […]

The post Monitoring methane? Now there is a better way to measure appeared first on Smithsonian Insider.

She was a stunning brown queen; drowned some 46 million years ago in a shallow lake in Montana. Her remains, recently recovered along the Flathead […]

The post New Montana ant species emerge from 46-million-year-old rock appeared first on Smithsonian Insider.

Seven fossil teeth exposed by the Panama Canal expansion project are the first evidence of a monkey on the North American continent before the Isthmus […]

The post First North American Monkey Fossils Found in Panama Canal Excavation appeared first on Smithsonian Insider.

A one-cubic-foot approach to studying biodiversity as showcased in the new Biocube exhibit at the Smithsonian’s National Museum of Natural History has led to the […]

The post New parasitic crab species discovered during Smithsonian Biocube work in Solomon Islands appeared first on Smithsonian Insider.

Chances are, if you’ve been stung by a jellyfish along the Chesapeake Bay it was by a sea nettle jellyfish–one of the most common and […]

The post Scientists discover common sea nettle jellyfish is actually two distinct species appeared first on Smithsonian Insider.

Mycoplasma hyopneumoniae is a prokaryotic pathogen that colonizes the respiratory ciliated epithelial cells in swine. Infected animals suffer respiratory lesions, causing major economic losses in the porcine industry. Characterization of the immunodominant membrane-associated proteins from M. hyopneumoniae may be instrumental in the development of new therapeutic approaches. Here, the crystal structure of P46, one of the main surface-antigen proteins, from M. hyopneumoniae is presented and shows N- and C-terminal α/β domains connected by a hinge. The structures solved in this work include a ligand-free open form of P46 (3.1 Å resolution) and two ligand-bound structures of P46 with maltose (2.5 Å resolution) and xylose (3.5 Å resolution) in open and closed conformations, respectively. The ligand-binding site is buried in the cleft between the domains at the hinge region. The two domains of P46 can rotate with respect to each other, giving open or closed alternative conformations. In agreement with this structural information, sequence analyses show similarities to substrate-binding members of the ABC transporter superfamily, with P46 facing the extracellular side as a functional subunit. In the structure with xylose, P46 was also bound to a high-affinity (Kd = 29 nM) Fab fragment from a monoclonal antibody, allowing the characterization of a structural epitope in P46 that exclusively involves residues from the C-terminal domain. The Fab structure in the complex with P46 shows only small conformational rearrangements in the six complementarity-determining regions (CDRs) with respect to the unbound Fab (the structure of which is also determined in this work at 1.95 Å resolution). The structural information that is now available should contribute to a better understanding of sugar nutrient intake by M. hyopneumoniae. This information will also allow the design of protocols and strategies for the generation of new vaccines against this important swine pathogen.

Leucocyte common antigen-related protein (LAR) is a post-synaptic type I transmembrane receptor protein that is important for neuronal functionality and is genetically coupled to neuronal disorders such as attention deficit hyperactivity disorder (ADHD). To understand the molecular function of LAR, structural and biochemical studies of protein fragments derived from the ectodomain of human LAR have been performed. The crystal structure of a fragment encompassing the first four FNIII domains (LARFN1–4) showed a characteristic L shape. SAXS data suggested limited flexibility within LARFN1–4, while rigid-body refinement of the SAXS data using the X-ray-derived atomic model showed a smaller angle between the domains defining the L shape compared with the crystal structure. The capabilities of the individual LAR fragments to interact with heparin was examined using microscale thermophoresis and heparin-affinity chromatography. The results showed that the three N-terminal immunoglobulin domains (LARIg1–3) and the four C-terminal FNIII domains (LARFN5–8) both bound heparin, while LARFN1–4 did not. The low-molecular-weight heparin drug Innohep induced a shift in hydrodynamic volume as assessed by size-exclusion chromatography of LARIg1–3 and LARFN5–8, while the chemically defined pentameric heparin drug Arixtra did not. Together, the presented results suggest the presence of an additional heparin-binding site in human LAR.

The Hope Diamond’s red glow has long been considered a unique property of that stone. Most blue diamonds produce a bluish-white phosphorescence if exposed to ultraviolet light. The few other diamonds known to emit red phosphorescence were commonly assumed to have been from the even larger original stone from which the Hope was cut.

The post Bombarded with ultraviolet light, the blue Hope diamond glows red appeared first on Smithsonian Insider.

The Cullinan Blue Diamond Necklace, featuring a bow motif with nine sparkling and extremely rare blue diamonds, recently joined the National Gem Collection in the […]

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More than 500 carats of rough diamonds were recently donated to the Department of Mineral Sciences of the Smithsonian’s Natural History Museum by Jewlers Mutual Insurance Co. of Neenah, Wis.

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Could the universe’s earliest stars have formed planets, and if so, what might they have looked like? That was the question Harvard-Smithsonian Center for Astrophysics […]

The post Diamonds are a planet’s best friend? In the early universe, perhaps appeared first on Smithsonian Insider.

Several weeks before it went on display in mid-November at the Smithsonian’s National Museum of Natural History, minerals curator Jeff Post stood in the museum’s […]

The post Colossal diamond’s eerie glow earns it a fiery name appeared first on Smithsonian Insider.

Keepers at the Smithsonian's National Zoo perform an artificial insemination procedure on a pair of Stanley Cranes. A Stanley Crane chick was successfully hatched on May 23, 2011.

The post Bird keepers at the National Zoo demonstrate the art of artificially inseminating Stanley cranes appeared first on Smithsonian Insider.

Knowing what we take from our oceans matters. Smithsonian scientists are developing tools to better understand and protect our oceans. One project they are working […]

The post Monitoring seafood catch data appeared first on Smithsonian Insider.

Tuvan ensemble Alash demonstrates various traditional throat singing styles that they use in their music. Smithsonian Folkways Recordings video.

The post Alash demonstrates throat singing styles appeared first on Smithsonian Insider.

White-faced capuchin monkeys in Panama’s Coiba National Park habitually use hammer-and-anvil stones to break hermit crab shells, snail shells, coconuts and other food items, according […]

The post Scientists observe stone tool use by Cebus monkeys appeared first on Smithsonian Insider.

At the 2018 Smithsonian Folklife Festival, Armenian participants Mariam Hovhannisyan and Stepan Toroyan—who were recently married—recreated a traditional ceremony on the National Mall, with contributions […]

The post Armenian Wedding Ceremony appeared first on Smithsonian Insider.

In Armenia, the completion of a carpet and cutting it from its loom is a significant rite of passion for young female weavers.

The post Smithsonian Folklife Festival: Armenian carpet-cutting ceremony appeared first on Smithsonian Insider.

The National Ecological Observatory (NEON) is a large-facility project managed by NEON, Inc., and funded by the National Science Foundation (NSF). NEON is a continental-scale […]

The post NEON begins to monitor changing ecology of U.S. appeared first on Smithsonian Insider.

Spending time in a beautiful garden can be transformative. In fact, some visitors to the Smithsonian’s Mary Livingston Ripley Garden in Washington D.C. have taken […]

The post Monarch Butterflies Make the Most of the Smithsonian’s Gardens appeared first on Smithsonian Insider.

The Earth’s changing climate could cause the extinction of up to a third of its parasite species by 2070, according to a global analysis reported […]

The post Study shows parasites may be among earliest victims of climate change appeared first on Smithsonian Insider.

To catch lizards on the offshore islands close to St. Croix in the Caribbean, Smithsonian herpetologist Nicole Angeli uses a lasso of thread looped at […]

The post Mongooses wiped them out. Now Nicole Angeli wants the St. Croix ground lizard home again appeared first on Smithsonian Insider.

Febuxostat and ethanol mol­ecules are linked into an O—H⋯O and O—H⋯N bonded chain structure.

The structural and nonlinear optical properties of a new anilinium hybrid crystal of chemical formula (C6H7NCl+·NO3−)3 have been investigated. The crystal structure was determined from single-crystal X-ray diffraction measurements performed at a temperature of 100 K which show that the compound crystallizes in a noncentrosymmetric space group (Pna21). The structural analysis was coupled with Hirshfeld surface analysis to evaluate the contribution of the different intermolecular interactions to the formation of supramolecular assemblies in the solid state that exhibit nonlinear optical features. This analysis reveals that the studied compound is characterized by a three-dimensional network of hydrogen bonds and the main contributions are provided by the O...H, C...H, H...H and Cl...H interactions, which alone represent ∼85% of the total contributions to the Hirshfeld surfaces. It is noteworthy that the halogen...H contributions are quite comparable with those of the H...H contacts. The nonlinear optical properties were investigated by nonlinear diffuse femtosecond-pulse reflectometry and the obtained results were compared with those of the reference material LiNbO3. The hybrid crystals exhibit notable second (SHG) and third (THG) harmonic generation which confirms its polarity is generated by the different intermolecular interactions. These measurements also highlight that the THG signal of the new anilinium compound normalized to its SHG counterpart is more pronounced than for LiNbO3.