Aujourd'hui le Moyen Age, archéologie et vie quotidienne en France Méridionale

[catalogue d'exposition], 1981-1983, Sénanque, Marseille, Arles, Toulon, Perpignan, Montpellier, Nice, GapInternational audienceCe catalogue d’exposition itinérante, fait la synthèse des principaux travaux du Laboratoire d’Archéologie Médiévale Méditerranéenne d’Aix-en-Provence (URA 6 du CRA CNRS) en 1981 réunis par l’équipe de Gabrielle Démians d’Archimbaud. L’habitat, les gestes de la vie quotidienne, le commerce et l’artisanat sont illustrés par les fouilles effectuées dans le Midi de la France, par de nombreux objets, en céramique, verre, pierre, os et métal ainsi que par les sources écrites, et les analyses de laboratoire, innovantes à cette époque

MEMO associated with an ErbB2 receptor phosphopeptide reveals a new phosphotyrosine motif.

International audienceTyrosine phosphorylations are essential in signal transduction. Recently, a new type of phosphotyrosine binding protein, MEMO (Mediator of ErbB2-driven cell motility), has been reported to bind specifically to an ErbB2-derived phosphorylated peptide encompassing Tyr-1227 (PYD). Structural and functional analyses of variants of this peptide revealed the minimum sequence required for MEMO recognition. Using a docking approach we have generated a structural model for MEMO/PYD complex and compare this new phosphotyrosine motif to SH2 and PTB phosphotyrosine motives

NMR and MD investigations of human galectin-1/oligosaccharide complexes.

International audienceThe specific recognition of carbohydrates by lectins plays a major role in many cellular processes. Galectin-1 belongs to a family of 15 structurally related beta-galactoside binding proteins that are able to control a variety of cellular events, including cell cycle regulation, adhesion, proliferation, and apoptosis. The three-dimensional structure of galectin-1 has been solved by x-ray crystallography in the free form and in complex with various carbohydrate ligands. In this work, we used a combination of two-dimensional NMR titration experiments and molecular-dynamics simulations with explicit solvent to study the mode of interaction between human galectin-1 and five galactose-containing ligands. Isothermal titration calorimetry measurements were performed to determine their affinities for galectin-1. The contribution of the different hexopyranose units in the protein-carbohydrate interaction was given particular consideration. Although the galactose moiety of each oligosaccharide is necessary for binding, it is not sufficient by itself. The nature of both the reducing sugar in the disaccharide and the interglycosidic linkage play essential roles in the binding to human galectin-1

Identification of a Src kinase SH3 binding site in the C-terminal domain of the human ErbB2 receptor tyrosine kinase

AbstractOverexpression of the ErbB2 receptor tyrosine kinase is associated with most aggressive tumors in breast cancer patients and is thus one of the main investigated therapeutic targets. Human ErbB2 C-terminal domain is an unstructured anchor that recruits specific adaptors for signaling cascades resulting in cell growth, differentiation and migration. Herein, we report the presence of a SH3 binding motif in the proline rich unfolded ErbB2 C-terminal region. NMR analysis of this motif supports a PPII helix conformation and the binding to Fyn-SH3 domain. The interaction of a kinase of the Src family with ErbB2 C-terminal domain could contribute to synergistic intracellular signaling and enhanced oncogenesis

Structural basis for galectin-1-dependent pre-B cell receptor (pre-BCR) activation.

International audienceDuring B cell differentiation in the bone marrow, the expression and activation of the pre-B cell receptor (pre-BCR) constitute crucial checkpoints for B cell development. Both constitutive and ligand-dependent pre-BCR activation modes have been described. The pre-BCR constitutes an immunoglobulin heavy chain (Ig?) and a surrogate light chain composed of the invariant ?5 and VpreB proteins. We previously showed that galectin-1 (GAL1), produced by bone marrow stromal cells, is a pre-BCR ligand that induces receptor clustering, leading to efficient pre-BII cell proliferation and differentiation. GAL1 interacts with the pre-BCR via the unique region of ?5 (?5-UR). Here, we investigated the solution structure of a minimal ?5-UR motif that interacts with GAL1. This motif adopts a stable helical conformation that docks onto a GAL1 hydrophobic surface adjacent to its carbohydrate binding site. We identified key hydrophobic residues from the ?5-UR as crucial for the interaction with GAL1 and for pre-BCR clustering. These residues involved in GAL1-induced pre-BCR activation are different from those essential for autonomous receptor activation. Overall, our results indicate that constitutive and ligand-induced pre-BCR activation could occur in a complementary manner

Protein-primed RNA synthesis in SARS-CoVs and structural basis for inhibition by AT-527

Summary How viruses from the Coronaviridae family initiate viral RNA synthesis is unknown. Here we show that the SARS-CoV-1 and −2 Ni dovirus R dRp- A ssociated N ucleotidyltransferase (NiRAN) domain on nsp12 uridylates the viral cofactor nsp8, forming a UMP-Nsp8 covalent intermediate that subsequently primes RNA synthesis from a poly(A) template; a protein-priming mechanism reminiscent of Picornaviridae enzymes. In parallel, the RdRp active site of nsp12 synthesizes a pppGpU primer, which primes (-)ssRNA synthesis at the precise genome-poly(A) junction. The guanosine analogue 5’-triphosphate AT-9010 (prodrug: AT-527) tightly binds to the NiRAN and inhibits both nsp8-labeling and the initiation of RNA synthesis. A 2.98 Å resolution Cryo-EM structure of the SARS-CoV-2 nsp12-nsp7-(nsp8) 2 /RNA/NTP quaternary complex shows AT-9010 simultaneously binds to both NiRAN and RdRp active site of nsp12, blocking their respective activities. AT-527 is currently in phase II clinical trials, and is a potent inhibitor of SARS-CoV-1 and −2, representing a promising drug for COVID-19 treatment

AT-752 targets multiple sites and activities on the Dengue virus replication enzyme NS5

International audienceAT-752 is a guanosine analogue prodrug active against dengue virus (DENV). In infected cells, it is metabolized into 2 '-methyl-2 '-fluoro guanosine 5 '-triphosphate (AT-9010) which inhibits RNA synthesis in acting as a RNA chain terminator. Here we show that AT-9010 has several modes of action on DENV full-length NS5. AT-9010 does not inhibit the primer pppApG synthesis step significantly. However, AT-9010 targets two NS5-associated enzyme activities, the RNA 2 '-O-MTase and the RNA-dependent RNA polymerase (RdRp) at its RNA elongation step. Crystal structure and RNA methyltransferase (MTase) activities of the DENV 2 MTase domain in complex with AT-9010 at 1.97 angstrom resolution shows the latter bound to the GTP/RNA-cap binding site, accounting for the observed inhibition of 2 '-O but not N7-methylation activity. AT-9010 is discriminated-10 to 14-fold against GTP at the NS5 active site of all four DENV1-4 NS5 RdRps, arguing for significant inhibi-tion through viral RNA synthesis termination. In Huh-7 cells, DENV1-4 are equally sensitive to AT-281, the free base of AT-752 (EC50 approximate to 0.50 mu M), suggesting broad spectrum antiviral properties of AT-752 against flaviviruses