Reconnaissance moleculaire d'acides nucleiques : conception de regulateurs artificiels de l'expression genetique

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Theories equationnelles et de contraintes pour la demonstration automatique en logique multi-modale

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : TD 82205 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Inhibiteurs bisubstrats de méthyltransférases virales

International audienceIn the last two decades, emerging viruses such as flaviviruses or coronaviruses have caused significant health andeconomic damage. Released upon infection in the host, methyltransferases are involved in the methylation of theviral messenger RNA cap. These methylations, on the N7 position of the guanosine and 2’ O position of the firstnucleotide transcribed in the cap, increase the stability of the viral messenger RNA in the cell while protecting itfrom the cellular receptors of the innate immune system. Their role is therefore essential and a deactivation of thesemethyltransferases could lead to the elimination of the virus by stimulation of the innate immune system. Followingthis objective, the work reported in this article concerns the design and evaluation of viral methyltransferaseinhibitors. The bisubstrate strategy was used to improve the specificity of these novel compoundsAu cours des deux dernières décennies, les virus émergents comme les Flavivirus ou les Coronavirus ont causé d'importants dommages sanitaires et économiques. Le complexe de réplication / transcription virale contient des enzymes essentielles au développement du virus. D'autres enzymes comme les méthyltransférases sont impliquées dans la méthylation de la coiffe de l'ARN messager viral. Ces méthylations, sur les positions N7 de la guanosine et 2'O du premier nucléotide transcrit dans la coiffe, augmentent la stabilité de l'ARN messager viral dans la cellule tout en le protégeant face aux récepteurs cellulaires du système immunitaire inné, comme RIG-I, qui ont la capacité de reconnaitre et entrainer l'élimination de cellules infectées. Leur rôle est donc primordial et une désactivation de ces méthyltransférases pourrait entrainer l'élimination du virus par stimulation du système immunitaire inné. Suivant cet objectif, les travaux de thèse reportés dans cet article concernent la synthèse et l'évaluation d'inhibiteurs de méthyltransférases virales. La conception de ces inhibiteurs repose sur une stratégie bisubstrat afin d'augmenter l'affinité et la spécificité de ces composés originaux

The biolabile 2'-O-pivaloyloxymethyl modification in an RNA helix: an NMR solution structure

International audienceThe pivaloylloxymethyl (PivOM) group is a biolabile 2'-O-ribose protection that is under development in a prodrug-based approach for siRNA applications. Besides an expected cellular uptake, nucleic acid sequences carrying PivOM showed also increased nuclease resistance and, in most cases, an affinity for complementary RNA. The r(CGCU*ACGC)dT:r(GCGUAGCG)dT model duplex containing a single modified residue (U*) was synthesized and its solution structure was determined by NMR. The duplex showed a maintained A-RNA helix. In U*, both 2'-O-acetal ester side chain and ring pucker presented a notable rigid conformation. The PivOM moiety was oriented with the carbonyl group turned outside the minor groove and with trans,-ac and -ac torsion angles around the C2'-O2',O2'-CA and CA-OB1 bonds respectively. Gauche effects and dipolar interactions between the PivOM and the backbone appeared to be the predominant factors influencing the PivOM conformation and the orientation of the two supplementary H acceptors suggested that hydration could also play a role in the duplex stability

Solid-phase synthesis of 5′-triphosphate 2′-5′-oligoadenylates analogs with 3′-O-biolabile groups and their evaluation as RNase L activators and antiviral drugs.

International audience5′-Triphosphate 2′-5′-oligoadenylate (2-5A) is the central player in the 2-5A system that is an innate immunity pathway in response to the presence of infectious agents. Intracellular endoribonuclease RNase L activated by 2-5A cleaves viral and cellular RNA resulting in apoptosis. The major limitations of 2-5A for therapeutic applications is the short biological half-life and poor cellular uptake. Modification of 2-5A with biolabile and lipophilic groups that facilitate its uptake, increase its in vivo stability and release the parent 2-5A drug in an intact form offer an alternative approach to therapeutic use of 2-5A. Here we have synthesized the trimeric and tetrameric 2-5A species bearing hydrophobic and enzymolabile pivaloyloxymethyl groups at 3′-positions and a triphosphate at the 5′-end. Both analogs were able to activate RNase L and the production of the trimer 2-5A (the most active) was scaled up to the milligram scale for antiviral evaluation in cells infected by influenza virus or respiratory syncytial virus. The trimer analog demonstrated some significant antiviral activity

Ecological catalysis and phytoextraction: symbiosis for future

International audienceMetallophyte plants derived from phytoextraction are used as starting materials to prepare novel polymetallic catalysts. Polymetallic catalyst activity is used in many Lewis acid catalyzed reactions according to the polymetallic catalyst preparation. The synergetic catalysis of these systems leads to efficient syntheses of complex biomolecules such as dihydropyrimidinone, 5'-capped DNA and RNA, and glycosyl aminoacid. These new polymetallic catalysts also bring new possibilities in Green Catalysis, that we named "Ecological Catalysis"

mRNA Capping by Venezuelan Equine Encephalitis Virus nsP1: Functional Characterization and Implications for Antiviral Research

International audienceno abstrac

X-ray structure and activities of an essential Mononegavirales L-protein domain

International audienceThe L protein of mononegaviruses harbours all catalytic activities for genome replication and transcription. It contains six conserved domains (CR-I to -VI; Fig. 1a). CR-III has been linked to polymerase and polyadenylation activity, CR-V to mRNA capping and CR-VI to cap methylation. However, how these activities are choreographed is poorly understood. Here we present the 2.2-Å X-ray structure and activities of CR-VI+, a portion of human Metapneumovirus L consisting of CR-VI and the poorly conserved region at its C terminus, the +domain. The CR-VI domain has a methyltransferase fold, which besides the typical S-adenosylmethionine-binding site (SAMP) also contains a novel pocket (NSP) that can accommodate a nucleoside. CR-VI lacks an obvious cap-binding site, and the SAMP-adjoining site holding the nucleotides undergoing methylation (SUBP) is unusually narrow because of the overhanging +domain. CR-VI+ sequentially methylates caps at their 2′O and N7 positions, and also displays nucleotide triphosphatase activity