Crystallization and Preliminary X-Ray Diffraction Analysis of Group 5 Mite Allergen fromDermatophagoides pteronyssinus

Crystals of the 14-kDa group 5 allergen fromDermatophagoides pteronyssinus(Der p 5) have been obtained at low pH and diffract to 3-Å resolution using a conventional x-ray source. The crystals belong to tetragonal space group P4₁2₁2 or P4₃2₁2, with unit cell parametersa=b= 114 Å andc= 234 Å. A self-rotation search revealed a 432 point symmetry and thus suggested 96 molecules in one unit cell, hence 12 monomers in each asymmetric unit.     

AtNAP1 represents an atypical SufB protein in Arabidopsis plastids

The assembly of iron-sulfur (Fe-S) clusters involves several pathways and in prokaryotes the mobilization of the sulfur (SUF) system is paramount for Fe-S biogenesis and repair during oxidative stress. The prokaryotic SUF system consists of six proteins: SufC is an ABC/ATPase that forms a complex with SufB and SufD, SufA acts as a scaffold protein, and SufE and SufS are involved in sulfur mobilization from cysteine. Despite the importance of Fe-S proteins in higher plant plastids, little is known regarding plastidic Fe-S cluster assembly. We have recently shown that Arabidopsis harbors an evolutionary conserved plastidic SufC protein (AtNAP7) capable of hydrolyzing ATP and interacting with the SufD homolog AtNAP6. Based on this and the prokaryotic SUF system we speculated that a SufB-like protein may exist in plastids. Here we demonstrate that the Arabidopsis plastid-localized SufB homolog AtNAP1 can complement SufB deficiency in Escherichia coli during oxidative stress. Furthermore, we demonstrate that AtNAP1 can interact with AtNAP7 inside living chloroplasts suggesting the presence of a plastidic AtNAP1.AtNAP6.AtNAP7 complex and remarkable evolutionary conservation of the SUF system. However, in contrast to prokaryotic SufB proteins with no associated ATPase activity we show that AtNAP1 is an iron-stimulated ATPase and that AtNAP1 is capable of forming homodimers. Our results suggest that AtNAP1 represents an atypical plastidic SufB-like protein important for Fe-S cluster assembly and for regulating iron homeostasis in Arabidopsis.     

Toward the synthesis of fine chemicals from lactose: preparation of d-xylo and l-lyxo-aldohexos-5-ulose derivatives

The transformation of (5R)-2,6-di-O-benzyl-5-C-methoxy-β-d-galactopyranosyl-(1→4)-2,3:5,6-di-O-isopropylidene-aldehydo-d-glucose dimethyl acetal (8) into partially protected derivatives of d-xylo- and l-lyxo-aldohexos-5-ulose has been reported, applying appropriate epimerisation methods to its 3′-O- and 4′-O-protected alcoholic derivatives.     

Well-being: towards an integration of psychology, neurobiology and social science

Well-being: towards an integration of psychology, neurobiology and social science     

Convenient preparation of L-arabino-hexos-5-ulose derivatives from lactose

2,6-di-O-benzyl- (9), 2-O-benzyl-3,4-O-isopropylidene- (19), and 2-O-benzyl-6-O-m-chlorobenzoyl-L-arabino-hexos-5-ulose (20) have been prepared using 4'-deoxy-4'-eno- and 6'-deoxy-5'-eno lactose dimethyl acetal derivatives 7 and 14 as key intermediates. The synthesis of enol ethers 7 and 14 has been performed with good yields by base-promoted elimination of acetone or p-toluenesulfonic acid from 2',6'-di-O-benzyl-, and 6'-O-p-toluenesulfonyl-2,3:5,6:3',4'-tri-O-isopropylidenelactose dimethyl acetal, respectively. The epoxidation with MCPBA of 7 and 14 in methanol or dichloromethane furnishes C-5'-methoxy and C-5'-m-chlorobenzoyloxy derivatives, easily transformed with good yields into L-arabino 5-ketoaldohexoses 9, 19 and 20.     

Neuritogenesis: polarization of constitutive exocytosis by effectors of Rho-family GTPases?

The sprouting of neurites from a neuron represents a highly specialized form of cellular morphogenesis that must involve coordinated changes in two major cellular processes at two membrane locations: reorganization of the cytoskeleton and redirection of membrane traffic from the trans-Golgi network to the plasma membrane of the growth tip. How exactly are these two processes linked and how is spatial and temporal coordination achieved at the first instance of neurite sprouting? Recent advances may have already revealed some, if not most of the pieces in the puzzle. We discuss below, with some extrapolations, of what has recently come to light, and what more is needed to construct a coherent picture.     

Structure and Binding Interface of the Cytosolic Tails of αXβ2 Integrin

Background

Integrins are signal transducer proteins involved in a number of vital physiological processes including cell adhesion, proliferation and migration. Integrin molecules are hetero-dimers composed of two distinct subunits, α and β. In humans, 18 α and 8 β subunits are combined into 24 different integrin molecules. Each of the subunit comprises a large extracellular domain, a single pass transmembrane segment and a cytosolic tail (CT). The CTs of integrins are vital for bidirectional signal transduction and in maintaining the resting state of the receptors. A large number of intracellular proteins have been found to interact with the CTs of integrins linking integrins to the cytoskeleton.

Methodology/Principal Findings

In this work, we have investigated structure and interactions of CTs of the leukocyte specific integrin αXβ2. We determined the atomic resolution structure of a myristoylated CT of αX in perdeuterated dodecylphosphocholine (DPC) by NMR spectroscopy. Our results reveal that the 35-residue long CT of αX adopts an α-helical conformation for residues F4-N17 at the N-terminal region. The remaining residues located at the C-terminal segment of αX delineate a long loop of irregular conformations. A segment of the loop maintains packing interactions with the helical structure by an extended non-polar surface of the αX CT. Interactions between αX and β2 CTs are demonstrated by ¹⁵N-¹H HSQC NMR experiments. We find that residues constituting the polar face of the helical conformation of αX are involved in interactions with the N-terminal residues of β2 CT. A docked structure of the CT complex indicates that a network of polar and/or salt-bridge interactions may sustain the heteromeric interactions.

Conclusions/Significance

The current study provides important insights into the conservation of interactions and structures among different CTs of integrins.     

Characterization of cymbidium mosaic virus coat protein gene and its expression in transgenic tobacco plants

Cymbidium mosaic virus (CyMV) is the most prevalent virus infecting orchids. Here, we report the isolation of partial cDNA clones encoding the genomic RNA of CyMV. Like most of the polyadenylated monopartite positive-strand RNA viruses, the open reading frame (ORF) coding for the viral coat protein (CP) is located at the 3 end. The ORF predicts a polypeptide chain of 220 amino acids with a molecular weight of 23 600. Sequence comparison of this ORF to the CP sequences of potato virus X(PVX) and white clover mosaic virus (WCIMV) revealed a strong amino acid homology in the mid-portion of the CP, but the overall homology was low. The CyMV CP gene was placed downstream of a cauliflower mosaic virus 35S promoter and the chimaeric gene was transferred into Nicotiana benthamiana. Transgenic plants expressing the CyMV CP were protected against CyMV infection.     

Medication by Proxy: The Devolution of Psychiatric Power and Shared Accountability to Psychopharmaceutical Use Among Soldiers in America’s Post-9/11 Wars

Culture, Medicine, and Psychiatry - With the United States military stretched thin in the “global war on terror,” military officials have embraced psychopharmaceuticals in the...