Insights from the x-ray crystal structure of coral 8R-lipoxygenase: Calcium activation via a C2-like domain and a structural basis of product chirality

Lipoxygenases (LOXs) catalyze the regio- and stereospecific dioxygenation of polyunsaturated membrane-embedded fatty acids. We report here the 3.2 Å resolution structure of 8R-LOX from the Caribbean sea whip coral Plexaura homomalla, a LOX isozyme with calcium dependence and the uncommon R chiral stereospecificity. Structural and spectroscopic analyses demonstrated calcium binding in a C2-like membrane-binding domain, illuminating the function of similar amino acids in calcium-activated mammalian 5-LOX, the key enzyme in the pathway to the pro-inflammatory leukotrienes. Mutation of Ca2+- ligating amino acids in 8R-LOX resulted not only in a diminished capacity to bind membranes, as monitored by fluorescence resonance energy transfer, but also in an associated loss of Ca2+-regulated enzyme activity. Moreover, a structural basis for R chiral specificity is also revealed; creation of a small oxygen pocket next to Gly428 (Ala in all S-LOX isozymes) promoted C-8 oxygenation with R chirality on the activated fatty acid substrate. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc

Flora of the Erie Islands: A Review of Floristic, Ecological and Historical Research and Conservation Activities, 1976 – 2010

Author Institution: Lake Erie Islands Chapter, Black Swamp Conservancy, Put-in-Bay, OHAuthor Institution: Biota of North American Program, Chapel Hill, NCAuthor Institution: Ontario Natural Heritage Information Centre, Ministry of Natural Resources, Ontario, CanadaThe purpose of this review is to survey the floristic, ecological and historical research about the Erie Islands and its flora since 1976 and to describe efforts to conserve Erie Island habitats. Island location records, surveys and multi-island inventories reveal that over 1,000 vascular plant taxa are known from the Erie Islands and new records continue to be found. Alvar habitats, rare globally, occur on the Erie Islands and are a focus of conservation efforts. Forest composition is primarily related to island elevation above lake level and moisture availability. Patterns of succession in abandoned vineyards and orchards are not the same due to differing agricultural practices prior to abandonment that favored different suites of invading species. Applying island biogeographic theory and methods to analyze the flora of the Erie Islands demonstrated that the indigenous flora on individual islands varies in relation to the size of an island in accordance with biogeographic theory whereas the non-indigenous flora on smaller islands is a constantly changing random subset of the non-indigenous flora of larger islands. Geological and palynological research about pre-settlement forests support the historic descriptions of these forests by early European settlers. Governmental and private efforts to preserve Erie Island habitats and the flora therein expanded significantly in the past 35 years. Efforts by the State of Ohio, the Province of Ontario, non-governmental organizations and island communities to acquire and conserve unique island habitats resulted in the preservation of important alvar, wetland and woodland habitat on large islands and the acquisition of Green Island, Middle Island and West Sister Island

A disorder to order transition accompanies catalysis in retinaldehyde dehydrogenase type II

Retinaldehyde dehydrogenase II (RalDH2) converts retinal to the transcriptional regulator retinoic acid in the developing embryo. The x-ray structure of the enzyme revealed an important structural difference between this protein and other aldehyde dehydrogenases of the same enzyme superfamily; a 20-amino acid span in the substrate access channel in retinaldehyde dehydrogenase II is disordered, whereas in other aldehyde dehydrogenases this region forms a well defined wall of the substrate access channel. We asked whether this disordered loop might order during the course of catalysis and provide a means for an enzyme that requires a large substrate access channel to restrict access to the catalytic machinery by smaller compounds that might potentially enter the active site and be metabolized. Our experiments, a combination of kinetic, spectroscopic, and crystallographic techniques, suggest that a disorder to order transition is linked to catalytic activity

The Prp19 U-box crystal structure suggests a common dimeric architecture for a class of oligomeric E3 ubiquitin ligases

Prp19 is an essential splicing factor and a member of the U-box family of E3 ubiquitin ligases. Prp19 forms a tetramer via a central coiled-coil domain. Here, we show the U-box domain of Prp19 exists as a dimer within the context of the Prp19 tetramer. A high-resolution structure of the homodimeric state of the Prp19 U-box was determined by X-ray crystallography. Mutation of the U-box dimer interface abrogates U-box dimer formation and is lethal in vivo. The structure of the U-box dimer enables construction of a complete model of Prp19 providing insights into how the tetrameric protein functions as an E3 ligase. Finally, comparison of the Prp19 U-box homodimer with the heterodimeric complex of BRCA1/BARD1 RING-finger domains uncovers a common architecture for a family of oligomeric U-box and RING-finger E3 ubiquitin ligases, which has mechanistic implications for E3 ligase-mediated polyubiquitination and E4 polyubiquitin ligases. © 2006 American Chemical Society

The organization of the transcriptional network in specific neuronal classes

Genome-wide expression profiling has aided the understanding of the molecular basis of neuronal diversity, but achieving broad functional insight remains a considerable challenge. Here, we perform the first systems-level analysis of microarray data from single neuronal populations using weighted gene co-expression network analysis to examine how neuronal transcriptome organization relates to neuronal function and diversity. We systematically validate network predictions using published proteomic and genomic data. Several network modules of co-expressed genes correspond to interneuron development programs, in which the hub genes are known to be critical for interneuron specification. Other co-expression modules relate to fundamental cellular functions, such as energy production, firing rate, trafficking, and synapses, suggesting that fundamental aspects of neuronal diversity are produced by quantitative variation in basic metabolic processes. We identify two transcriptionally distinct mitochondrial modules and demonstrate that one corresponds to mitochondria enriched in neuronal processes and synapses, whereas the other represents a population restricted to the soma. Finally, we show that galectin-1 is a new interneuron marker, and we validate network predictions in vivo using Rgs4 and Dlx1/2 knockout mice. These analyses provide a basis for understanding how specific aspects of neuronal phenotypic diversity are organized at the transcriptional level

Rapid and safe response to low-dose carbamazepine in neonatal epilepsy

To evaluate treatment responses in benign familial neonatal epilepsy (BFNE)

Sheep Updates 2009

This session covers seven papers from different authors: 1. Scouring Management and Worm Control, Brown Besier, Department of Agriculture and Food, Western Australia 2.Breeding sheep for resistance to breech strike:- Selection results in WA, LJE Karlsson, JC Greeff & AC Schlink, Department of Agriculture and Food, Western Australia 3.Future Ewe - matching genetics to the production system, Mark Ferguson, Department of Agriculture and Food, Western Australia 4. Within-flock selection of ewes: opportunities for gains in reproduction, Greg Leeand Sue Hatcher, NSW Department of Primary Industries & Australian CRCforSheep Industry Innovation (Orange) 5. Managing Merinos on Murrayfield, Bruce Michael, Murryfield, Bruny Island, Tasmania 6. Managing [breech] flystrike in [unmulesed] sheep, Rob Woodgate, Darren Michael, Mandy Curnow and Julia Smith, Department of Agriculture and Food, Western Australia 7. Value of Pregnancy Scanning and Differential Feeding of Dry, Single amd Twin Ewes, John Young, Farming Systems Analysis Service, Kojonup, WA, Andrew Thompson, Chris Oldham Department of Agriculture and Food, Western Australi

A mechanism of viral immune evasion revealed by cryo-EM analysis of the TAP transporter

Cellular immunity against viral infection and tumor cells depends on antigen presentation by the major histocompatibility complex class 1 molecules (MHC I). Intracellular antigenic peptides are transported into the endoplasmic reticulum (ER) by the transporter associated with antigen processing (TAP) and then loaded onto the nascent MHC I, which are exported to the cell surface and present peptides to the immune system1. Cytotoxic T lymphocytes recognize non-self peptides and program the infected or malignant cells for apoptosis. Defects in TAP account for immunodeficiency and tumor development. To escape immune surveillance, some viruses have evolved strategies to either down-regulate TAP expression or directly inhibit TAP activity. To date neither the architecture of TAP nor the mechanism of viral inhibition has been elucidated at the structural level. In this study we describe the cryo-electron microscopy (cryo-EM) structure of human TAP in complex with its inhibitor ICP47, a small protein produced by the herpes simplex virus I. We show that the twelve transmembrane helices and two cytosolic nucleotide-binding domains (NBDs) of the transporter adopt an inward-facing conformation with the two NBDs separated. The viral inhibitor ICP47 forms a long helical hairpin, which plugs the translocation pathway of TAP from the cytoplasmic side. Association of ICP47 precludes substrate binding and also prevents NBD closure necessary for ATP hydrolysis. This work illustrates a striking example of immune evasion by persistent viruses. By blocking viral antigens from entering the ER, herpes simplex virus is hidden from cytotoxic T lymphocytes, which may contribute to establishing a lifelong infection in the host

Impact of Spacecraft Shielding on Direct Ionization Soft Error Rates for Sub-130 nm Technologies

We use ray tracing software to model various levels of spacecraft shielding complexity and energy deposition pulse height analysis to study how it affects the direct ionization soft error rate of microelectronic components in space. The analysis incorporates the galactic cosmic ray background, trapped proton, and solar heavy ion environments as well as the October 1989 and July 2000 solar particle events

Compendium of Total Ionizing Dose and Displacement Damage for Candidate Spacecraft Electronics for NASA

Vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage is studied. Devices tested include optoelectronics, digital, analog, linear, and hybrid devices