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Science Highlights

  • Structure of Chinese Herbal-based Medicine Captured by ATP on a Human tRNA Synthetase

    For approximately 2,000 years, the Chinese have been using the Chang Shan herb to treat malaria-induced fevers. A derivative of the herb's active ingredient has also been utilized in clinical trials for cancer and other therapies. Previous studies showed that the derivative, called halofuginone (HF), binds to an enzyme known as prolyl-tRNA synthetase (ProRS). Inhibition of ProRS by HF requires the additional presence of adenosine triphosphate (ATP), interestingly one of ProRS's three native substrates. Recent studies have shed new light on the structural interplay of ProRS, HF and ATP.

  • Structure of Human Argonaute2: A Programmable Ribonuclease

    Argonaute proteins play an important role in the biological process of RNA interference (RNAi). Scientists have now determined the crystal structure of human Argonaute2, thereby making progress toward a detailed understanding of Ago2 interactions with target RNA which may benefit the design of novel RNAi therapeutics.

  • Structure of the DUF2233 Domain in Bacteria and the Stuttering-associated UCE Glycoprotein

    UCE plays a key role in the functioning of lysosomes, cellular sacs full of digestive enzymes that break down bacteria, viruses and worn-out cell parts for recycling. When this recycling process goes awry, it can cause rare metabolic diseases such as Tay-Sachs and Gaucher, which often cause death in affected children by their early teens. Three years ago, researchers discovered that three mutations in UCE itself were linked to persistent stuttering that is passed down in families.

  • The Long-Sought Structure of a-Catenin Defines Its Functions for Cell-Cell Interactions

    Cells bind each other using specialized cell surface adhesion complexes called adherens junctions. These complexes direct the formation of tight, Velcro-like contacts that are essential for the development, architecture, maintenance, and function of tissues in all higher organisms. Exactly how this cell to cell binding is accomplished has not been fully understood. Researchers from the Florida campus of The Scripps Research Institute (TSRI) have now solved a piece of this puzzle by determining the structure of α-catenin using SSRL's Beam Line 11-1.

  • The Structure and Dynamics of Eukaryotic Glutaminyl-tRNA Synthetase

    Aminoacyl-tRNA synthetases are required in all three domains of life to add the correct amino acid to its cognate tRNA, an essential step in protein synthesis. Despite their importance, no structure had been reported for any full-length eukaryotic, glutaminyl-tRNA synthetase (GlnRS), although structural data for two prokaryotic GlnRS species exists.

  • Allosteric Activation and Modulation of Pentameric Ligand-gated Ion Channels

    Cys-loop receptors in eukaryotic cells control fast synaptic transmission and are important targets for various therapeutics which include general anesthetics. Although technical challenges have limited the determination of high-resolution structures for Cys-loop receptors, researchers from the University of Pittsburgh School of Medicine have taken advantage of two homologous proteins: the pentameric ligand-gated ion channels (pLGICs) found in the bacterium Erwinia chrysanthemi (ELIC) and the cyanobacterium Gloebacter violaceus (GLIC). The researchers carried out crystallographic studies of these pLGICs on SSRL Beam Line 12-2, investigating the structural underpinnings of the pLGIC activation process and the structural basis of anesthetic modulation of pLGICs.

  • Systematic Expansion of Porous Crystals to Include Large Molecules

    Recently, scientists at the University of California, Berkeley and Lawrence Berkeley National Laboratory and their collaborators synthesized a series of metal-organic frameworks (MOFs) with pores up to 98 Å in diameter—large enough to house protein molecules. For the first time the researchers were able to design strategies to overcome three major obstacles to increasing pore capacity...

  • The Lassa Virus Nucleoprotein Appears to Exhibit Conformational Control of Genome Binding

    Lassa virus is endemic in Western Africa, and is the most common cause of viral hemorrhagic fever, infecting an estimated 300,000-500,000 people annually. It is also the hemorrhagic fever most frequently transported out of Africa to the United States and Europe. Understanding the key proteins of Lassa virus and any Achilles' Heels written into their protein structures will enable development of therapeutics for medical defense. Recent analysis of the crystal structure of the virus' RNA binding domain done at SSRL may have revealed one promising area of vulnerability.

  • Structural Basis for Iron Piracy by Pathogenic Neisseria

    Of the 11 species of Neisseria bacteria that colonize humans, 9 of them coexist peacefully with us. However, two can cause serious diseases N. gonorrhoeae, responsible for the sexually transmitted disease gonorrhea, and N. meningitidis, which causes septicemia and meningitis. Commercially available vaccines exist for four of the five known disease-causing serogroups of N. meningitidis (A, B, C, Y, W135) but no vaccine exists to combat serogroup B (menB); nor is there a vaccine available against N. gonorrhoeae. One target for vaccine development against menB and N. gonorrhoeae is the iron transporters found on the pathogens' surfaces. Cut off their access to iron and these pathogens cannot survive.

  • Unusual Structure and Dynamics of an Artificial Enzyme Created in a Test Tube

    Until now this has been achieved only when extensive knowledge of the mechanism of the reaction is available. Recently, however, researchers have used a clever in vitro strategy to synthesize an artificial RNA ligase enzyme capable of a previously unknown catalytic activity, and to do so they began with a protein not associated with catalysis. A team of scientists led by Burckhard Seelig of the University of Minnesota have now determined the unique structure of this novel biocatalyst using NMR and synchrotron-based Zn K-edge EXAFS at SSRL's Beam Line 9-3

  • The Elements of Stroke

    Brain injuries from stroke are both common and costly. The NIH has estimated that the total annual cost of stroke in the United States is $43 billion including direct medical care and the costs related to lost productivity. It has been recognized that rapid diagnosis and treatment is essential to limit neuronal cell death from either a bleed into the brain (hemorrhagic stroke) or a blockage that deprives part of the brain of oxygen (ischemic stroke). The Synchrotron Medical Imaging Team, a group of Canadian, US, and European scientists from diverse backgrounds are collaborating to better understand the underlying chemistry of stroke and how to best image and treat stroke patients.

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