Analysis of ribosome biogenesis factor-modules in yeast cells depleted from pre-ribosomes

Formation of eukaryotic ribosomes requires more than 150 biogenesis factors which transiently interact with the nascent ribosomal subunits. Previously, many pre-ribosomal intermediates could be distinguished by their protein composition and rRNA precursor (pre-rRNA) content. We purified complexes of ribosome biogenesis factors from yeast cells in which de novo synthesis of rRNA precursors was down-regulated by genetic means. We compared the protein composition of these largely pre-rRNA free assemblies with the one of analogous pre-ribosomal preparations by semi-quantitative mass spectrometry. The experimental setup minimizes the possibility that the analysed pre-rRNA free protein modules were derived from (partially) disrupted pre-ribosomal particles and provides thereby strong evidence for their pre-ribosome independent existence. In support of the validity of this approach (i) the predicted composition of the analysed protein modules was in agreement with previously described rRNA-free complexes and (ii) in most of the cases we could identify new candidate members of reported protein modules. An unexpected outcome of these analyses was that free large ribosomal subunits are associated with a specific set of ribosome biogenesis factors in cells where neo-production of nascent ribosomes was blocked. The data presented strengthen the idea that assembly of eukaryotic pre-ribosomal particles can result from transient association of distinct building blocks

Rapid Synthesis of L-Idosyl Glycosyl Donors from α- Thioglucosides for the Preparation of Heparin Disaccharides

A new methodology for the synthesis of the most challenging heparin building block has been developed. Orthogonally protected L-idosyl glycosyl donors were prepared by C5 epimerization of the corresponding thioglucosides using the hydroboration/oxidation method followed by a 4,6-acetal formation. The -anomeric configuration was crucial and the bulky C4 substituent was advantageous for the high L-ido diastereoselectivity. The 4,6-arylmethylene group proved to be a directing element in glycosylation thereby stereoselective -idosylation could be achieved by using idosyl donors without a C-2 participating group

Synthese de 2'-desoxy-beta-D-disaccharides. Application a la synthese de fragments d'orthosomycines

SIGLEINIST T 72607 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

PREPARATION OF PYRANOID GLYCAL DERIVATIVES FROM PHENYL THIOGLYCOSIDES AND GLYCOSYL PHENYL SULFONES

none5---noneFERNANDEZMAYORALAS A; A. MARRA; TRUMTEL M; VEYRIERES A; SINAY PFernandezmayoralas, A; Marra, Alberto; Trumtel, M; Veyrieres, A; Sinay, P

CONVENIENT SYNTHESES OF SUBSTITUTED PYRANOID GLYCALS FROM THIOPHENYL GLYCOSIDES AND GLYCOSYL PHENYLSULFONES

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