The structure of the CstF-77 homodimer provides insights into CstF assembly

The cleavage stimulation factor (CstF) is essential for the first step of poly(A) tail formation at the 3' ends of mRNAs. This heterotrimeric complex is built around the 77-kDa protein bridging both CstF-64 and CstF-50 subunits. We have solved the crystal structure of the 77-kDa protein from Encephalitozoon cuniculi at a resolution of 2 Å. The structure folds around 11 Half-a-TPR repeats defining two domains. The crystal structure reveals a tight homodimer exposing phylogenetically conserved areas for interaction with protein partners. Mapping experiments identify the C-terminal region of Rna14p, the yeast counterpart of CstF-77, as the docking domain for Rna15p, the yeast CstF-64 homologue

Molecular basis of Diamond–Blackfan anemia: structure and function analysis of RPS19

Diamond–Blackfan anemia (DBA) is a rare congenital disease linked to mutations in the ribosomal protein genes rps19, rps24 and rps17. It belongs to the emerging class of ribosomal disorders. To understand the impact of DBA mutations on RPS19 function, we have solved the crystal structure of RPS19 from Pyrococcus abyssi. The protein forms a five α-helix bundle organized around a central amphipathic α-helix, which corresponds to the DBA mutation hot spot. From the structure, we classify DBA mutations relative to their respective impact on protein folding (class I) or on surface properties (class II). Class II mutations cluster into two conserved basic patches. In vivo analysis in yeast demonstrates an essential role for class II residues in the incorporation into pre-40S ribosomal particles. This data indicate that missense mutations in DBA primarily affect the capacity of the protein to be incorporated into pre-ribosomes, thus blocking maturation of the pre-40S particles

Simulation of resonant tunneling heterostructures: numerical comparison of a complete Schr{ö}dinger-Poisson system and a reduced nonlinear model

Two different models are compared for the simulation of the transverse electronic transport through an heterostructure: a $1D$ self-consistent Schr{ö}dinger-Poisson model with a numerically heavy treatment of resonant states and a reduced model derived from an accurate asymptotic nonlinear analysis. After checking the agreement at the qualitative and quantitative level on quite well understood bifurcation diagrams, the reduced model is used to tune double well configurations for which nonlinearly interacting resonant states actually occur in the complete self-consistent model

Synthesis and biological evaluation of novel substituted pyrrolo[1,2-a]quinoxaline derivatives as inhibitors of the human protein kinase CK2

Herein we describe the synthesis and properties of substituted phenylaminopyrrolo[1,2-a]quinoxaline-carboxylic acid derivatives as a novel class of potent inhibitors of the human protein kinase CK2. A set of 15 compounds was designed and synthesized using convenient and straightforward synthesis protocols. The compounds were tested for inhibition of human protein kinase CK2, which is a potential drug target for many diseases including inflammatory disorders and cancer. New inhibitors with IC50 in the micro- and sub-micromolar range were identified. The most promising compound, the 4-[(3-chlorophenyl)amino]pyrrolo[1,2-a]quinoxaline-3-carboxylic acid 1c inhibited human CK2 with an IC50 of 49 nM. Our findings indicate that pyrrolo[1,2-a]quinoxalines are a promising starting scaffold for further development and optimization of human protein kinase CK2 inhibitorsFil: Guillon, Jean. Universite de Bordeaux; Francia;Fil: Le Borgne, Marc. Université de Lyon; Francia;Fil: Rimbault, Charlotte. Universite de Bordeaux; Francia;Fil: Moreau, Stéphane. Universite de Bordeaux; Francia;Fil: Savrimoutou, Solène. Universite de Bordeaux; Francia;Fil: Pinaud, Noël. Universite de Bordeaux; Francia;Fil: Baratin, Sophie. Universite de Bordeaux; Francia;Fil: Marchivie, Mathieu. Universite de Bordeaux; Francia;Fil: Roche, Séverine. Universite de Bordeaux; Francia;Fil: Bollacke, Andre. Institut für Pharmazeutische und Medizinische Chemie. Westfälische Wilhelms-Universität Münster; Alemania;Fil: Pecci, Adali. Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Fisiol., Biol.molecular y Neurociencias; Argentina;Fil: Alvarez, Lautaro Damian. Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unid.microanal.y Met.fisicos En Quim.org.(i); Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Quimica Organica;Fil: Desplat, Vanessa. Universite de Bordeaux; Francia;Fil: Joachim, Jose. Institut für Pharmazeutische und Medizinische Chemie. Westfälische Wilhelms-Universität Münster; Alemania

Exploring TAR–RNA aptamer loop–loop interaction by X-ray crystallography, UV spectroscopy and surface plasmon resonance

In HIV-1, trans-activation of transcription of the viral genome is regulated by an imperfect hairpin, the trans-activating responsive (TAR) RNA element, located at the 5′ untranslated end of all viral transcripts. TAR acts as a binding site for viral and cellular proteins. In an attempt to identify RNA ligands that would interfere with the virus life-cycle by interacting with TAR, an in vitro selection was previously carried out. RNA hairpins that formed kissing-loop dimers with TAR were selected [Ducongé F. and Toulmé JJ (1999) RNA, 5:1605–1614]. We describe here the crystal structure of TAR bound to a high-affinity RNA aptamer. The two hairpins form a kissing complex and interact through six Watson–Crick base pairs. The complex adopts an overall conformation with an inter-helix angle of 28.1°, thus contrasting with previously reported solution and modelling studies. Structural analysis reveals that inter-backbone hydrogen bonds between ribose 2′ hydroxyl and phosphate oxygens at the stem-loop junctions can be formed. Thermal denaturation and surface plasmon resonance experiments with chemically modified 2′-O-methyl incorporated into both hairpins at key positions, clearly demonstrate the involvement of this intermolecular network of hydrogen bonds in complex stability

Implantable theranostic device for in vivo real-time NMR evaluation of drug impact in brain tumors

Abstract The evaluation of the efficacy of a drug is a fundamental step in the development of new treatments or in personalized therapeutic strategies and patient management. Ideally, this evaluation should be rapid, possibly in real time, easy to perform and reliable. In addition, it should be associated with as few adverse effects as possible for the patient. In this study, we present a device designed to meet these goals for assessing therapeutic response. This theranostic device is based on the use of magnetic resonance imaging and spectroscopy for the diagnostic aspect and on the application of the convection-enhanced delivery technique for the therapeutic aspect. The miniaturized device is implantable and can be used in vivo in a target tissue. In this study, the device was applied to rodent glioma models with local administration of choline kinase inhibitor and acquisition of magnetic resonance images and spectra at 7 Tesla. The variations in the concentration of key metabolites measured by the device during the administration of the molecules demonstrate the relevance of the approach and the potential of the device

Minimally invasive implantable NMR microcoils for in vivo metabolic profiling of microliter volumes

International audienceIntroductionThe use of implanted NMR microcoils still remains a relatively unexploited research area, without emerging or significant biomedical applications. The limitations inherent to implanted NMR coils derive obviously from the relatively weak detection sensitivity of NMR, hindering great challenges for nano-volume analyses. In addition, the necessity to preserve tissue during microprobe implantation imposes severe constraints on the geometry and structure of the NMR microcoil. In this study, we present in vitro and in vivo results obtained with innovative and minimally invasive microcoils.MethodsAn example of implantable NMR microprobe is shown in Figure 1. This filar-type architecture is based on the use of twisted copper microwires (diameter of 150 μm). The twisted wires are inserted inside a polyamide tubing (outer diameter of 380 μm). A biocompatible glue is used to seal the polyamide tube, while tuning and matching capacitors are connected to the two sides of the wire. For in vivo experiments, cannulae were stereotaxically positionned the day before the insertion of the NMR microcoils in the brain of male wistar rats. Experiments were performed at 7 T and 17.2 T. NMR spectra were acquired using a PRESS sequence. 3D MRI acquisitions were performed using a ZTE (zero echo time) sequence.Results/DiscussionThe quality factor of the loaded coils was ranging between 100 and 120. The full width at half maximum of water peak were measured to 6 Hz. In vivo results are illustrated in Figure 2 with a PRESS NMR spectrum obtained in the rat brain with a twisted microcoil (a volume coil was used for selective excitation). In this particular example of water-suppressed acquisition (240 averages, 10-minutes acquisition) at 7 Tesla, main peaks of brain metabolites (NAA, glu, gln, pCr, Cr, etc) can be easily identified and quantified. The ZTE MRI image (right side of Figure 1) shows the sensitive detection zone of the microprobe (volume evaluated to 500 nL) extending to about 200 μm away from the wire.ConclusionsThe MRS/MRI results obtained in vitro and in vivo illustrate the relevance of the microcoil design with respect to spectral resolution, detection sensitivity, spatial selectivity and limited invasiveness. Foreseen applications include the investigation of metabolism in microliter volumes in physiological conditions and in diseases with metabolic dysfunctions (tumoral environement, neurodegenerative pathologies, etc)

Crystal structure of a fluoro analogue of 3,4-(methylenedioxy)

The X-ray crystal structure of 6-fluoro-3,4-methylenedioxyamphetamine hydrochloride, a fluoro analogue of 3,4-(methylenedioxy)amphetamine, was established. It crystallizes in the orthorhombic space group Pbac with cell parameters a = 24.679(4)Å, b = 9.873(4)Å, c = 9.253(5)Å, V = 2254.5(16)Å3 and Z = 8. The crystal structure was refined to final values of R1 = 0.0601 and wR2 = 0.1479. An X-ray crystal structure analysis revealed that each molecule features strong intermolecular N-H…Cl hydrogen bonds