<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Structural studies of RNA Polymerase III transcription"^^ . "RNA Polymerase III (Pol III) produces small, non-coding RNAs with fundamental\r\nfunctions in the eukaryotic cell, including translation, splicing and protein sorting. While\r\nstructures of unbound and transcribing Pol III have been solved and provided valuable\r\nmechanistic insights into Pol III transcription, snapshots of molecular interactions that\r\nunderlie Pol III activation and repression are lacking. In this thesis I address these\r\nquestions with structural studies of the Sarrachomyces cerevisiae Pol III transcription\r\napparatus. I present high-resolution cryo-EM reconstructions of Pol III bound to its\r\nprincipal transcription initiation factor TFIIIB that were used to build atomic models. The\r\ncomplex was observed in different functional states, including two early intermediates in\r\nwhich the DNA duplex is closed, an open DNA complex, and an initially transcribing\r\ncomplex with RNA in the active site. The structures reveal an extremely tight, multivalent\r\ninteraction between TFIIIB and promoter DNA, and explain how TFIIIB recruits Pol III.\r\nTogether, TFIIIB and Pol III subunit C37 activate the intrinsic transcription factor-like\r\nfunction of the Pol III-specific heterotrimer to initiate the melting of double-stranded\r\nDNA, in a mechanism similar to that of the Pol II system.\r\nI further present a high resolution structure of Pol III bound to the negative regulator\r\nMaf1, that explains how Maf1 achieves transcription repression by preventing interaction\r\nwith TFIIIB. Maf1 occupies a position on Pol III that overlaps with the binding site of\r\npromoter DNA and TFIIIB. Furthermore, by mimicking the shape and electrostatic charge\r\nof a double-stranded DNA backbone, Maf1 further sequesters a mobile domain of Pol III\r\nsubunit C34, which seals off the active site cleft and makes it inaccessible to bind DNA.\r\nLastly, I describe a recombinant expression system for the six-subunit, 520 kDa transcription\r\nfactor TFIIIC and subcomplexes thereof. Negative stain electron microscopy\r\nof a complex between the tA module of TFIIIC and TFIIIB provide the first molecular\r\ninsights into how TFIIIC recruits TFIIIB and positions it upstream of the transcription\r\nstart site. Biochemical experiments further show that the tA module is displaced after or\r\nconcomitant with Pol III recruitment, establishing it as an assembly factor rather than a\r\nbona fide transcription factor."^^ . "2019" . . . . . . . "Matthias Kopano"^^ . "Vorländer"^^ . "Matthias Kopano Vorländer"^^ . . . . . . "Structural studies of RNA Polymerase III transcription (PDF)"^^ . . . "Thesis_MV_18032019_final-compressed.pdf"^^ . . . "Structural studies of RNA Polymerase III transcription (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #27386 \n\nStructural studies of RNA Polymerase III transcription\n\n" . "text/html" . . . "000 Allgemeines, Wissenschaft, Informatik"@de . "000 Generalities, Science"@en . . . "500 Naturwissenschaften und Mathematik"@de . "500 Natural sciences and mathematics"@en . .