<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "The mechanism and regulation of rRNA methylation by\r\nthe Box C/D sRNP enzyme in solution"^^ . "The biogenesis of the ribosome requires a series of essential modifications of ribosomal\r\nRNAs (rRNAs) and their precursor pre-rRNAs. The most abundant of such modifications is\r\nthe methylation of the ribose 2 ́-OH, which occurs at over 100 rRNA sites in humans. rRNA\r\nmethylation is known to increase the stability of the ribosome and to be required for accurate\r\nand efficient protein translation. While 2’-O methylation sites are known to cluster around the\r\nfunctional centres of the ribosome, the abundance of methylation at each site is known to\r\nvary, which may provide a mechanism to fine tune ribosomal function, creating specialized\r\nribosome populations.\r\nIn\r\neukaryotes\r\nand\r\narchaea,\r\nrRNA\r\n2’-O\r\nmethylation is mediated by Box C/D\r\nribonucleoprotein particles (RNPs). These particles, referred to as small nucleolar RNPs\r\n(snoRNPs) in eukaryotes and small RNPs (sRNPs) in archaea, use a guide RNA in order to\r\ndirect the methylation of a specific nucleotide on the substrate rRNA. In archaea, each small\r\nguide RNA (sRNA) is responsible for the methylation of two rRNA sites using two different\r\nseparate guide regions.\r\nDespite several structures of archaeal Box C/D sRNPs being available, the molecular basis\r\nfor the regulation of the enzyme and the consequent generation of varying methylation\r\nabundances across different rRNA sites remains elusive.\r\nIn order to understand the mechanism and regulation of the enzyme, I investigated the\r\nbiochemical properties of archaeal Box C/D sRNPs reconstituted in vitro . Through a\r\ncombination of biochemical and nuclear magnetic resonance (NMR)-based assays, I could\r\nshow that archaeal RNPs catalyse the methylation of different substrate rRNA sites with\r\nvarying degrees of efficiency and cooperativity. Furthermore, using low-resolution small\r\nangle scattering (SAS) techniques, I could show that addition of substrate RNAs onto some\r\nsRNPs is correlated with the complex undergoing a transition between different oligomeric\r\nand/or conformational states, thereby contextualising the multiple sRNP structures observed\r\nin previous studies.\r\nIn the second part of my work, I used a combination of distance restraints derived from NMR\r\nand low-resolution information from SAS to obtain the structures of an archaeal sRNP bound\r\nto either of its two substrate RNAs by an integrative structural biology approach. As this\r\nparticle contains flexible regions, the work required the development of a novel algorithm\r\ncapable of dealing with NMR/SAS signals arising from ensembles, rather than single\r\nconformers. Using this tool, I could derive the populations of conformers within ensembles of\r\nRNPs bound to different substrate RNAs, which provide a structural basis for the varying\r\nmethylation efficiency of the enzyme.\r\nUltimately, the work presented here provides a model for understanding one of the\r\nmechanism through which specialised ribosome populations are generated in vivo and\r\ncontributes to the development of novel techniques for integrative structure modelling of\r\nflexible systems."^^ . "2020" . . . . . . . "Andrea"^^ . "Graziadei"^^ . "Andrea Graziadei"^^ . . . . . . "The mechanism and regulation of rRNA methylation by\r\nthe Box C/D sRNP enzyme in solution (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "The mechanism and regulation of rRNA methylation by\r\nthe Box C/D sRNP enzyme in solution (PDF)"^^ . . . "AndreaGraziadei_thesis_toprint.pdf"^^ . . "HTML Summary of #26084 \n\nThe mechanism and regulation of rRNA methylation by \nthe Box C/D sRNP enzyme in solution\n\n" . "text/html" . . . "570 Biowissenschaften, Biologie"@de . "570 Life sciences"@en . .