Identification of the prebiotic translation apparatus within the contemporary ribosome

A structural element that could have existed independently in the prebiotic era was identified at the active site of the contemporary ribosome. It is suggested to have functioned as a proto-ribosome catalyzing peptide bond formation and non-coded elongation in the same manner that contemporary ribosomes exert positional catalysis, namely by accommodating the reactants in stereochemistry favourable for inline nucleophilic attack. This simple apparatus is a dimer of self-folding RNA units that could have assembled spontaneously into a symmetrical pocket-like structure, sufficiently efficient to be preserved throughout evolution as the active site of modern ribosomes, thus presenting a conceivable starting point for translation.Here we discuss the proto-ribosome emergence hypothesis and show that the tendency for dimerization, a prerequisite for obtaining the catalytic centre, is linked to the fold of its two components, indicating functional selection at the molecular level in the prebiotic era and supporting the existence of dimeric proto-ribosome

Santé globale, santé de première ligne, santé communautaire (présentation du projet de "la case de santé" à Toulouse)

Next to define health concepts of primary care, global health, community health and local observatory of health, we present a health center project in Toulouse (France) with an associative statue: La case de santé . This organization will be managed by a multi-field health team non hierarchical (general practitioner, wise woman, nurse, coordinator) , in collaboration with an users s committee. The organization centers it s action on four Toulouse s neighbours whom represent the population diversity of the town.It poses two principles: the acquisition by the health team of knowledges and practices allowing to answer in best at the first care requests, with an independent formation which avoids any influence from industrial or corporatist interest; and the individual systemic approach to try to understand and act on the nonmedical determinants of health (social, economical ) .TOULOUSE3-BU Santé-Centrale (315552105) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

High Resolution Structure of the Large Ribosomal Subunit from a Mesophilic Eubacterium

AbstractWe describe the high resolution structure of the large ribosomal subunit from Deinococcus radiodurans (D50S), a gram-positive mesophile suitable for binding of antibiotics and functionally relevant ligands. The over-all structure of D50S is similar to that from the archae bacterium Haloarcula marismortui (H50S); however, a detailed comparison revealed significant differences, for example, in the orientation of nucleotides in peptidyl transferase center and in the structures of many ribosomal proteins. Analysis of ribosomal features involved in dynamic aspects of protein biosynthesis that are partially or fully disordered in H50S revealed the conformations of intersubunit bridges in unbound subunits, suggesting how they may change upon subunit association and how movements of the L1-stalk may facilitate the exit of tRNA