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.

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 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.

It’s not an exaggeration to say Hedrick was ecstatic when she peered into her inverted phase contrast microscope and found "Amphisolenia quadrispina" floating in her sample. “For 20 years I’ve been hoping to see something like this,” she says.

The post From the Bay of Bengal, a dinoflagellate makes its way to the Smithsonian appeared first on Smithsonian Insider.

Eleven bats remain in the National Zoo’s colony. The initial challenge the team faced was how to feed the animals. Virginia big-eared bats, which are a subspecies of the Townsend’s big-eared bat (Corynorhinuss townsendii), eat while flying.

The post Captive colony of Virginia big-eared bats providing valuable lessons in battle against deadly white-nose syndrome appeared first on Smithsonian Insider.

"Just like mirrors in a changing room show you a clothing outfit from all sides, interstellar dust clouds act like mirrors to show us different sides of the supernova," Rest explains.

The post Astronomers see supernova from a new angle appeared first on Smithsonian Insider.

The funding will allow the National Science Resources Center to validate its LASER (Leadership Assistance for Science Education Reform) Model. LASER, a systemic approach to reform, is a set of processes and strategies designed to help state, district and school leadership teams effectively implement and sustain
high-quality science education for elementary, middle and secondary school students.

The post NSRC to receive $25 million Investing in Innovation grant from U.S. Department of Education appeared first on Smithsonian Insider.

To understand the effects of road salting on ants, Michael Kaspari of the Smithsonian Tropical Research Institute and the University of Oklahoma led a team that looked at how ant colonies are affected by these conditions; their research is published in a recent issue of the journal Ecological Entomology.

The post Study reveals road salt may promote health and well-being of roadside ant colonies appeared first on Smithsonian Insider.

A diminutive bat with cinnamon-brown coloring collected in 1979 in Ecuador by mammalogist Don Wilson of the Smithsonian’s National Museum of Natural History represents a new species a recent paper in the journal “Mammalian Biology” has revealed.

The post New species of bat named from central coastal Ecuador appeared first on Smithsonian Insider.

Our Sun can be a menace when it sends out powerful blasts of radiation towards the Earth. Astronomers keenly watch the Sun in hopes of being able to predict these eruptions. New research shows that one-third of the Sun’s blasts are “sneak attacks” that may occur without warning.

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Thepytus carmen, a newly described species of butterfly from Brazil, was recently named in memory of Carmen Lúcia Buck in recognition of the gracious support […]

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A. sediba was discovered in 2008 in the Malapa Cave at the Cradle of Humankind World Heritage Site located outside Johannesburg.

The post Skeletal casts of early hominin ancestor from Africa donated to National Museum of Natural History appeared first on Smithsonian Insider.


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.

Recent work has added dozens of new measurements to star-forming regions in the Milky Way. These measurements have changed the map of the Milky Way, indicating our galaxy has four spiral arms, not two, as previously thought.

The post Very Large Baseline Array telescope is helping Smithsonian astronomers remap Milky Way and Andromeda galaxies appeared first on Smithsonian Insider.

Researchers from the Smithsonian Institution and the University of Florida have announced the discovery of a bone fragment, approximately 13,000 years old, in Florida with an incised image of a mammoth or mastodon.

The post Bone fragment is only Ice Age artwork from America to show a “proboscidean” appeared first on Smithsonian Insider.

A scientist from the Smithsonian Tropical Research Institute uses a pick to dislodge the fossil skull of an extinct toothed whale from sediments on the […]

The post Fossil skull of an extinct toothed whale excavated from Panamanian sediments appeared first on Smithsonian Insider.

Astronomers using NASA's Chandra X-ray Observatory discovered the first pair of supermassive black holes in a spiral galaxy similar to the Milky Way. Approximately 160 million light years from Earth, the pair is the nearest known such phenomenon.

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Just as people use airplanes to fly overseas, marine snails may use birds to fly over land,” said Mark Torchin, staff scientist at the Smithsonian.

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Although cold and gaseous rather than a desert world, the newfound planet Kepler-16b is still the closest astronomers have come to discovering Luke Skywalker's home world of Tatooine.

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The fossil represents the youngest nodosaur ever discovered, and the only known specimen of a new genus and species of dinosaur that lived approximately 110 million years ago during the Early Cretaceous Era.

The post New dinosaur species named from hatchling fossil donated to National Museum of Natural History appeared first on Smithsonian Insider.

Ornithologists Carla Dove and Storrs Olson used 700- to 1,100-year-old feathers from a long extinct species of Hawaiian ibis to help determine the bird’s place in the ibis family tree. The feathers are the only known plumage of any of the prehistorically extinct birds that once inhabited the Hawaiian Islands.

The post Fossil feathers from a Hawaiian cave help reveal lineage of extinct, flightless ibis appeared first on Smithsonian Insider.

Molynocoelia erwini, is a new species of fruit fly from Ecuador recently described by USDA entomologist Allen Norrbom, who works in the Systematic Entomology Laboratory […]

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Nearly 20 years after the Smithsonian Conservation Biology Institute became the first to produce an Eld’s deer fawn through artificial insemination, SCBI scientists have now contributed to the birth of the first Eld’s deer via in vitro fertilization.

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"X-Ray Vision: Fish Inside Out," is a new exhibition of striking x-rays that reveal the complex bone structure of fishes in the collections of the Smithsonian's National Museum of Natural History.

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The Smithsonian Tropical Research Institute has released the first completely portable bilingual species identification guide for the shore fishes of the tropical Eastern Pacific as a free iPhone application.

The post First fish App from the Smithsonian free on iTunes. “The Smithsonian Guide to the Shore Fishes of the Tropical Eastern Pacific” appeared first on Smithsonian Insider.

Astronomers using NASA's Hubble Space Telescope have found a cluster of young, blue stars encircling the first intermediate-mass black hole ever discovered. The presence of the star cluster suggests that the black hole was once at the core of a now-disintegrated dwarf galaxy.

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Scientists conducting deep-sea research in the Galapagos have described a new species of catshark. The new shark is approximately a foot long and has a chocolate-brown coloration with pale, irregularly distributed spots on its body. The spotted patterns appear to be unique to each individual.

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The snakes are not only eating the area’s birds, but also the birds’ eggs straight from the nest.

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The specimen’s skull measures 24 centimeters, roughly the size of a regulation NFL football. The shell which was recovered nearby – and is believed to belong to the same species – measures 172 centimeters, or about 5 feet 7 inches, long.

The post Giant prehistoric turtle from Colombia chomped everything in sight–including crocodiles! appeared first on Smithsonian Insider.

The newfound jets may be related to mysterious gamma-ray bubbles that Fermi detected in 2010. Those bubbles also stretch 27,000 light-years from the center of the Milky Way.

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A July 12 news alert from NASA indicates a X1.4 class solar flare erupted from the center of the Sun, peaking July 12 at 12:52 P.M.

The post Coronal mass ejection from July 12 solar flare headed toward Earth; minor geomagnetic storm activity predicted appeared first on Smithsonian Insider.

Astronomers using NASA's Chandra X-ray Observatory have detected X-rays emitted by the debris from the explosion of supernova 1957D.

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They observed that no plugs were ever formed during mating trials, but instead, females exposed to many males produced the amorphous plugs during the egg-laying process.

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JoVonn Hill, a research associate with the Mississippi Agricultural and Forestry Experiment Station at Mississippi State University, recently borrowed 32,000 grasshoppers from the Smithsonian’s National […]

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What scientists found was that the domestic turkey that ends up on the dinner table exhibits less genetic variation than its ancestral wild counterparts, which were first domesticated in 800 B.C..

The post Today’s domestic turkeys are genetically distinct from wild ancestors appeared first on Smithsonian Insider.

This past summer, Laura Walker became the first scientist to collect slime molds from soils at the Barro Colorado Nature Monument in Panama, a reserve administered by the Smithsonain since 1946.

The post Panama’s slime molds get attention from Arkansas University grad student appeared first on Smithsonian Insider.

Frontispiece illustration of “flies” from the 1882 book American game fishes, their habits, habitat, and peculiarities; how, when, and where to angle for them, featuring […]

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Tiny as a mouse with a ‘prout brown’ body and three black stripes on its back Monodelphis gardneri from Peru bears little resemblance to its much larger cousin the North American opossum.

The post Tiny new Peruvian opossum comes from a great big family appeared first on Smithsonian Insider.

This image of a wild giant panda was taken by a trail camera in a remote forest in central China. As few as 1,600 giant […]

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The process of freezing materials such as fertilized eggs – cryopreservation – provides researchers with a tool to repopulate endangered species.

The post Klondike, puppy born from a frozen embryo, fetches good news for endangered animals appeared first on Smithsonian Insider.

Even dying stars could host planets with life – and if such life exists, we might be able to detect it within the next decade. […]

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                  The Smithsonian Libraries will open its new exhibition “Whales: From Bone to Book” in the Smithsonian’s National Museum […]

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Scientists at the Smithsonian Conservation Biology Institute are celebrating the birth of a female Przewalski’s (Cha-VAL-skee) horse—the first to be born via artificial insemination. The […]

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Unlocking the mysteries of animal migration through precise, near real-time tracking can solve major conservation challenges and transform wildlife science worldwide. For the past year, […]

The post New project to unlock migration mysteries from air 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.

Chip a tooth and expose a nerve and the result can be a searing sensitivity to hot and cold. The hard outer layer of a […]

The post Scientists map pathway from narwhals’ sensitive tusk to brain appeared first on Smithsonian Insider.

Save the Rhinos! Save the Elephants! Save the humans?! It seems strange to be connecting our own fate to that of wildlife but new research […]

The post Losing large mammals increases human risk from rodent-borne diseases appeared first on Smithsonian Insider.

Identifying larval stages of marine fishes in the open ocean is difficult because the young fishes often bear little or no resemblance to the adults […]

The post Smithsonian scientists link fish larva in Florida to new sea bass species from Curacao appeared first on Smithsonian Insider.

WHAT A new species of stick catfish from South America, so called because the thin, elongated bodies of these fish mimic sticks. About 5 inches […]

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