The membrane protein EsaA is a conserved component of the type VIIb secretion system. Limited proteolysis of purified EsaA from Staphylococcus aureus USA300 identified a stable 48 kDa fragment, which was mapped by fingerprint mass spectrometry to an uncharacterized extracellular segment of EsaA. Analysis by circular dichroism spectroscopy showed that this fragment folds into a single stable domain made of mostly α-helices with a melting point of 34.5°C. Size-exclusion chromatography combined with multi-angle light scattering indicated the formation of a dimer of the purified extracellular domain. Octahedral crystals were grown in 0.2 M ammonium citrate tribasic pH 7.0, 16% PEG 3350 using the hanging-drop vapor-diffusion method. Diffraction data were analyzed to 4.0 Å resolution, showing that the crystals belonged to the enantiomorphic tetragonal space groups P41212 or P43212, with unit-cell parameters a = 197.5, b = 197.5, c = 368.3 Å, α = β = γ = 90°.

Cytisine, a natural product with high affinity for clinically relevant nicotinic acetylcholine receptors (nAChRs), is used as a smoking-cessation agent. The compound displays an excellent clinical profile and hence there is an interest in derivatives that may be further improved or find use in the treatment of other conditions. Here, the binding of a cytisine derivative modified by the addition of a 3-(hydroxypropyl) moiety (ligand 4) to Aplysia californica acetylcholine-binding protein (AcAChBP), a surrogate for nAChR orthosteric binding sites, was investigated. Isothermal titration calorimetry revealed that the favorable binding of cytisine and its derivative to AcAChBP is driven by the enthalpic contribution, which dominates an unfavorable entropic component. Although ligand 4 had a less unfavorable entropic contribution compared with cytisine, the affinity for AcAChBP was significantly diminished owing to the magnitude of the reduction in the enthalpic component. The high-resolution crystal structure of the AcAChBP–4 complex indicated close similarities in the protein–ligand interactions involving the parts of 4 common to cytisine. The point of difference, the 3-(hydroxypropyl) substituent, appears to influence the conformation of the Met133 side chain and helps to form an ordered solvent structure at the edge of the orthosteric binding site.

The Smithsonian’s National Air and Space Museum has opened a new Public Observatory that contains a 16-inch, 3,000-pound Boller and Chivens telescope, on loan from the Smithsonian Astrophysical Observatory. Through this powerful telescope, museum visitors can now observe the sun (with a special filter), the moon and the brighter stars and planets, such as Venus, Jupiter and Saturn, during daylight hours. Funding for the project was provided by the National Science Foundation.

The post The Smithsonian’s National Air and Space Museum opens new Public Observatory on the Mall in Washington, D.C. appeared first on Smithsonian Insider.

The National Zoo has been awarded a grant from the U.S. Fish and Wildlife Service to establish a captive population of the Virginia big-eared bat at the National Zoo’s Conservation & Research Center near Front Royal, Va. Only 15,000 Virginia big-eared bats remain living in caves in West Virginia, Virginia, Kentucky and North Carolina, and these are threatened by the white-nose syndrome.

The post In face of crisis, National Zoo to start captive population of Virginia big-eared bats appeared first on Smithsonian Insider.

The Smithsonian’s National Air and Space Museum recently obtained two monumental instruments on loan from NASA’s Goddard Space Flight Center.

The post New Acquisition: Corrective instruments from the Hubble Space Telescope appeared first on Smithsonian Insider.

In their laboratory, scientists from the University of Cambridge, the University of Southampton and the Smithsonian Tropical Research Institute in Panama, observed as a number of adult locusts walked along a horizontal ladder. After covering the right or left eye of an insect, the scientists observed a significant increase in the error rate of rungs missed by the front leg on the side of the covered eye.

The post For first time, scientists prove locusts use vision to place their legs when walking appeared first on Smithsonian Insider.

The Kepler spacecraft was launched in March of 2009 to study extrasolar planets. One of its major goals is the detection of terrestrial planets in habitable zones.

The post Kepler spacecraft used by Smithsonian astronomers to find other earths appeared first on Smithsonian Insider.

Known as one of the greatest racehorses of his day and sire to more winning horses than any other American thoroughbred before or since, this Smithsonian loan returned the legendary Lexington's remains to the town of his birthplace some 160 years after he was born.

The post One hundred sixty years after his birth a racehorse’s bones return to Lexington appeared first on Smithsonian Insider.

On the Smithsonian Tropical Research Institute's Barro Colorado Island in the Panama Canal, staff members are taking down a network of seven tall Automated Radio Telemetry System towers used to track animals wearing radio-transmitters. Scientists on the island are switching to GPS and camera trap systems to produce more data with less infrastructure.

The post GPS and camera traps to replace radio antennas in tracking animals on Barro Colorado Island appeared first on Smithsonian Insider.

Faced with insufficient time and inadequate library resources to tackle the problem on their own, they instead posted a catalog of specimen images to Facebook and turned to their network of colleagues for help.

The post Facebook friends help scientists quickly identify nearly 5,000 fish specimens collected in Guyana appeared first on Smithsonian Insider.

Discovery, the longest-serving orbiter in the space shuttle fleet, will be accepted into the Smithsonian’s National Air and Space Museum collection. The space shuttle has been the icon for American spaceflight for a generation, and Discovery has flown every type of mission during its 27-year career.

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NASA's Kepler spacecraft is proving itself to be a prolific planet hunter. Within just the first four months of data, astronomers have found evidence for more than 1,200 planetary candidates. Of those, 408 reside in systems containing two or more planets, and most of those look very different than our solar system.

The post The Kepler spacecraft’s astounding haul of multiple-planet systems appeared first on Smithsonian Insider.

In a new paper appearing this week in Science, a group of biologists have shown that females themselves can also limit the evolution of increased elaboration.

The post Females can place limits on evolution of attractive features in males, research shows appeared first on Smithsonian Insider.

NASA's Kepler spacecraft has spotted a planet that alternately runs late and
early in its orbit because a second, "invisible" world is tugging on it.
This is the first definite detection of a previously unknown planet using
this method.

The post Invisible world “spotted” tugging on visible planet by Kepler spacecraft appeared first on Smithsonian Insider.

Depending on where the fish disperse from, the use of ‘stepping stones', flotsam or simply being an adult can help in the journey to find a new home.

The post Ability to raft with flotsam and use non-reef habitats helps tropical fish journey to new places, study finds appeared first on Smithsonian Insider.

Smithsonian scientists and collaborators have determined the evolutionary family tree for one of the most strikingly diverse and endangered bird families in the world, the Hawaiian honeycreepers.

The post Complete evolutionary tree of the Hawaiian honeycreepers traced by Smithsonian scientists, collaborators appeared first on Smithsonian Insider.

The image shows one of the most active and turbulent regions of star birth in our galaxy, a region called Cygnus X.

The post New Spitzer Space Telescope image shows space nursery appeared first on Smithsonian Insider.

For the last 1,000 days the Infrared Array Camera, aboard NASA’s Spitzer Space Telescope, has been operating continuously to probe the universe from its most distant regions to our local solar neighborhood.

The post Top 10 gallery celebrates the Infrared Array Camera aboard the Spitzer Space Telescope appeared first on Smithsonian Insider.

NASA's next Small Explorer (SMEX) mission to study the little-understood lower levels of the sun's atmosphere has been fully integrated and final testing is underway.

The post NASA’s IRIS spacecraft scheduled to launch in April appeared first on Smithsonian Insider.

Small migratory male birds that winter in a stressful environment age faster than those that winter in a high-quality habitat, according to research stemming from […]

The post Small migratory birds age faster in stressful places, study reveals appeared first on Smithsonian Insider.

The Smithsonian’s National Air and Space Museum announced that it will receive a $6 million donation from the Thomas W. Haas Foundation to establish an […]

The post Air and Space Museum receives $6 million donation for Public Observatory Program appeared first on Smithsonian Insider.

In 2009, during an expedition by a Russian research ship, a small length of yellow flesh about 5 centimeters long was dredged up from the […]

The post Last seen 140 years ago, deep sea worm resurfaces, delighting scientists appeared first on Smithsonian Insider.

Santa Claus and his sleigh full of gifts has been upstaged early this holiday season by news of autonomous drones possibly delivering packages to your […]

The post Package-delivering drones? Q&A with Roger Connor of the National Air and Space Museum appeared first on Smithsonian Insider.

Life in the universe might be even rarer than we thought. Recently, astronomers looking for potentially habitable worlds have targeted red dwarf stars because they […]

The post Harsh space weather dooms life on red-dwarf planets appeared first on Smithsonian Insider.

A mysterious X-ray signal has been found in a detailed study of galaxy clusters using NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton. One intriguing possibility […]

The post Mysterious X-ray signal from space appeared first on Smithsonian Insider.

Over the vast, empty reaches of interstellar space, countless small molecules tumble quietly though the cold vacuum. Forged in the fusion furnaces of ancient stars […]

The post Mysterious molecules in space appeared first on Smithsonian Insider.

To paraphrase Mark Twain, the report of the Kepler spacecraft’s death was greatly exaggerated. Despite a malfunction that ended its primary mission in May 2013, […]

The post Kepler spacecraft proves it can still find planets appeared first on Smithsonian Insider.

The Smithsonian’s National Air and Space Museum has acquired a large collection from the Sir Arthur C. Clarke Trust. The collection consists of 87 cubic […]

The post Arthur C. Clarke papers come to Air and Space Museum Archives appeared first on Smithsonian Insider.

While studying the social dynamics of the bearded saki, a primate living in the rainforests of Suriname, primatologist Tremaine Gregory of the Smithsonian Conservation Biology […]

The post Study: Male bonding brings peace, lets primates live in big groups appeared first on Smithsonian Insider.

In one of the largest studies of its kind, a volunteer-fueled camera trapping effort showed that where coyotes have moved in, cats are nowhere to […]

The post Cats Don’t Roam in Places Coyotes Call Home appeared first on Smithsonian Insider.

The Smithsonian is embarking on a multi-project partnership with Kickstarter, the funding platform for creative projects. The inaugural project will support conservation of Neil Armstrong’s […]

The post Kickstarter funding: Neil Armstrong’s Apollo 11 spacesuit appeared first on Smithsonian Insider.

Recently crowned the “astronomy photo of the year” by Slate’s Bad Astronomy blog, a new image of a region of Orion’s belt reveals the deepest […]

The post Stunning deep space photo reveals new details of Orion nebulae appeared first on Smithsonian Insider.

A new analysis of the fossil record by scientists at the Smithsonian’s National Museum of Natural History has revealed that the structure of plant and […]

The post Smithsonian Scientists Trace Anthropocene Roots to Early Human Activity appeared first on Smithsonian Insider.

It is rare but not entirely uncommon to see a manatee swimming in the Atlantic waters of Maryland and Virginia. This one was dead, however, […]

The post In face of mass extinctions, Smithsonian’s Global Genome Initiative quietly saves world’s DNA appeared first on Smithsonian Insider.

Because there is no polite way to ask a mite to sit still for its portrait, Gary Bauchan often gives his tiny subjects a shot […]

The post Enjoy Face Time with Seven of Earth’s 3-5 Million Mite Species appeared first on Smithsonian Insider.

Crustaceans that thrive in the vastness of the open ocean have no place to hide from their predators. Consequently, many creatures that live at depths […]

The post Tiny ocean crustaceans wear invisibility cloak of living bacteria appeared first on Smithsonian Insider.

Flitting swiftly through the darkness above the tropical forest canopy in Central and South America, a group of cute little bats with dog-like faces have […]

The post More sky puppies! Scientists discover two new species of dog-faced bat appeared first on Smithsonian Insider.

When “2001: A Space Odyssey” premiered April 2, 1968 at Washington, D.C.’s Uptown Theater—not far from the Smithsonian’s National Air and Space Museum—not everyone was […]

The post The real history behind science fiction’s ‘2001: A Space Odyssey’ appeared first on Smithsonian Insider.

Imagine a place where ice cream never drips. Ice cream lovers, how far would you be willing to go to avoid that heartbreaking moment where […]

The post Space is the best place to eat ice cream 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.

Victor J. F. Kitano, Yoko Ohyama, Chiyomi Hayashida, Junta Ito, Mari Okayasu, Takuya Sato, Toru Ogasawara, Maki Tsujita, Akemi Kakino, Jun Shimada, Tatsuya Sawamura, and Yoshiyuki Hakeda

Osteoporosis is associated with vessel diseases attributed to hyperlipidemia, and bone resorption by multinucleated osteoclasts is related to lipid metabolism. In this study, we generated low-density lipoprotein receptor (LDLR)/lectin-like oxidized LDL receptor-1 (LOX-1) double knockout (dKO) mice. We found that, like LDLR single KO (sKO), LDLR/LOX-1 dKO impaired cell-cell fusion of osteoclast-like cells (OCLs). LDLR/LOX-1 dKO and LDLR sKO preosteoclasts exhibited decreased uptake of LDL. The cell surface cholesterol levels of both LDLR/LOX-1 dKO and LDLR sKO osteoclasts were lower than the levels of wild-type OCLs. Additionally, the amount of phosphatidylethanolamine (PE) on the cell surface was attenuated in LDLR/LOX-1 dKO and LDLR sKO pre-OCLs, while the PE distribution in wild-type OCLs was concentrated on the filopodia in contact with neighboring cells. Abrogation of the ATP binding cassette G1 (ABCG1) transporter, which transfers PE to the cell surface, caused decreased PE translocation to the cell surface and subsequent cell-cell fusion. The findings of this study indicate the involvement of a novel cascade (LDLR~ABCG1~PE translocation to cell surface~cell-cell fusion) in multinucleation of OCLs.

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 […]

The post Cullinan Blue Diamond Necklace appeared first on Smithsonian Insider.

The new island visible in the satellite photograph is the top of a giant shield volcano located on the rift axis in the Red Sea where the continental plates of Africa and Arabia are pulling apart.

The post A hot new island has just surfaced in the Red Sea. What’s going on? Smithsonian scientists explain. appeared first on Smithsonian Insider.

We’ve seen a serious series of super moons this summer and the show’s not over yet. Mark your calendars: the next one will light up […]

The post Cutting through the dust: Radar shows moon’s true face for first time appeared first on Smithsonian Insider.

Admired from afar by the ancient Romans, the moon was once deified as a goddess, Luna. Today, two-thousand years later, geologists who scrutinize the moon’s […]

The post Orbiting Camera Unveils New Moon in Air and Space Museum Exhibition appeared first on Smithsonian Insider.

To the Hopewell Culture, ancient Native Americans who sought out the exotic from near and far, metal was a rare and precious resource. Copper, found […]

The post Ancient Native American beads traced to otherworldy source: an iron meteorite appeared first on Smithsonian Insider.

Monday, Aug. 21 was an unusual day across North America. Early in the morning, families, colleagues and tourists were searching for special solar glasses with […]

The post Crowds gather at Air and Space Museum to view solar eclipse appeared first on Smithsonian Insider.

As average annual temperatures increase, mosquitoes have also been on the move—up the mountains of the Hawaiian islands. Once a refuge for native birds susceptible […]

The post Scientists race to find genetic clues as malaria decimates rare Hawaiian honeycreepers appeared first on Smithsonian Insider.

The transformations from the primitive cells of the centered Bravais lattices to the corresponding centered cells have conventionally been listed as three-by-three matrices that transform three-space lattice vectors. Using those three-by-three matrices when working in the six-dimensional space of lattices represented as Selling scalars as used in Delone (Delaunay) reduction, one could transform to the three-space representation, apply the three-by-three matrices and then back-transform to the six-space representation, but it is much simpler to have the equivalent six-by-six matrices and apply them directly. The general form of the transformation from the three-space matrix to the corresponding matrix operating on Selling scalars (expressed in space S6) is derived, and the particular S6matrices for the centered Delone types are listed. (Note: in his later publications, Boris Delaunay used the Russian version of his surname, Delone.)