Stanford Synchrotron Radiation Lightsource

Botulinum neurotoxin is produced by the bacteria Clostridium botulinum and is the most potent toxin known, inducing a potentially fatal paralysis known as "botulism." Botulism can occur in a number of ways, including infection through open wounds or in the intestinal tract, or after consuming contaminated food in which toxin has been produced. In the USA, infant botulism is the most common manifestation of the disease-some speculate whether its prevalence is linked to sudden infant death syndrome. On the other hand, these neurotoxins have also become a powerful therapeutic tool for treating a variety of neurological, ophthalmic, and other disorders manifested by abnormal, excessive, or inappropriate muscle contractions.

Scientists from Caltech have solved the crystal structure of an ATP-binding Cassette (ABC) transporter called HI1470/1 from the bacteria Haemophilus influenzae. This particular transporter, which is a member of a large family of related proteins prevalent in most organisms including humans, is responsible for moving nutrients across cell membranes. The structure of HI1470/1 exhibits an alternate conformation to that previously observed for the related transporter BtuCD, such that their pathways for moving nutrients open to opposite sides of the membrane. These results give scientists a look at both the beginning and ending stages of how proteins transport nutrients across the membrane bilayers that surround all cells.

In rheumatoid arthritis and Crohn's disease, the immune system overreacts, provoking too much inflammation. One method of treatment is to inhibit the immune protein that incites inflammation, called tumor necrosis factor (TNF). Currently available anti-TNF therapeutics have made a significant difference to patients, but are costly to manufacture and require an I.V. or injection. Sunesis Pharmaceuticals of South San Francisco, in collaboration with Biogen Idec, is researching small molecules that will inhibit TNF. The advantage of using small molecules is that they can be administered orally, and be produced much less expensively.

Stanford Synchrotron Radiation Laboratory (SSRL) and Stanford researchers have now shown that the electrical performance of plastic semiconductors can be controlled and improved with surface treatments. In their research, published in Nature Materials, they showed they could align the small crystals within the polymer by applying a thin layer of another kind of organic molecule on to the surface. The highly-oriented crystals give the material better performance in conducting electricity. Researchers used x-ray scattering facilities at SSRL to determine the orientation of the crystals.

Researchers from the City of Hope cancer research and treatment center in Duarte, California, determined the crystal structure of the protein that controls this defense system in bacteria called Bacillus caldolyticus. Unless stopped, viral DNA slips into bacterial DNA, where it gets copied many times over, and then destroys its host. To protect bacterial cells, the control protein ensures the proper ratio between two enzymes, the "swords" and the "shields." The sword enzyme slashes invading viral DNA into useless pieces. The shield enzyme adds a protective layer to bacterial DNA, so the sword will not cut its master. Too few shields lead to bacterial cell death, and too many shields protect the viral DNA as well.

After years of wondering how organisms managed to create medically valuable natural products, like antibiotics and anti-fungal agents, chemists have discovered the surprisingly simple secret by shining x-ray light on the problem. MIT and Harvard researchers used crystallography beam lines at the Stanford Synchrotron Radiation Laboratory and the Advanced Light Source in Berkeley for their research.

Genes, which are made of nucleic acids (DNA or RNA) contain the instructions for how to make proteins, but still enzymes made of proteins are needed to replGenes, which are made of nucleic acids (DNA or RNA) contain the instructions for how to make proteins, but still enzymes made of proteins are needed to replicate the genes. This paradox was addressed ~20 years ago with the realization that some kinds of RNA can act as enzymes. These RNA enzymes, or ribozymes, are accordingly made of the genetic RNA material, but they act as chemical catalysts. This means that ribozymes would have enabled the first self-replicating molecules, also made of RNA, to copy themselves.

Billions of years ago, primitive bacteria developed a way to harness sunlight to split water molecules into protons, electrons and oxygen-the cornerstone of photosynthesis. Now, a team of scientists has taken a major step toward understanding this process by deriving the precise structure of the catalytic metal-cluster center containing four manganese atoms and one calcium atom (Mn₄Ca) that drives this water-splitting reaction. This catalytic center resides in a large protein complex, called photosystem II, found in plants, green algae, and cyanobacteria. The international team was led by scientists from LBNL, and includes scientists from Germany's Technical and Free Universities in Berlin, the Max Planck Institute in Mülheim, and from SSRL.

Scientists have for the first time used an extremely short and intense coherent soft x-ray laser pulse to successfully obtain a high-resolution image of a nano-scale object before the sample was destroyed by the energy impact of the pulse. The experiment, conducted at Deutsches Elektronen-Synchrotron (DESY) in Hamburg by a collaboration that included researchers from the Photon Science Directorate at SLAC, also set a speed record of 25 femtoseconds for the duration of the x-ray pulse used to acquire the image. The results are published in the November 12 online edition and the December printed edition of Nature Physics.

Researchers have for the first time obtained a high-resolution structure of a three-molecule receptor-ligand complex that could help shed light on neurodegenerative diseases such as Parkinson's. The complex includes two receptor molecules, called GFRα3, bound with its ligand, artemin, which fit together like a lock and key. These molecules play a key role in chemical signal transmission and in the development and health of neurons.