Structural basis of RNA polymerase III transcription initiation.
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Date
2018-01-17Author
Abascal-Palacios, G
Ramsay, EP
Beuron, F
Morris, E
Vannini, A
Type
Journal Article
Metadata
Show full item recordAbstract
RNA polymerase (Pol) III transcribes essential non-coding RNAs, including the entire pool of transfer RNAs, the 5S ribosomal RNA and the U6 spliceosomal RNA, and is often deregulated in cancer cells. The initiation of gene transcription by Pol III requires the activity of the transcription factor TFIIIB to form a transcriptionally active Pol III preinitiation complex (PIC). Here we present electron microscopy reconstructions of Pol III PICs at 3.4-4.0 Å and a reconstruction of unbound apo-Pol III at 3.1 Å. TFIIIB fully encircles the DNA and restructures Pol III. In particular, binding of the TFIIIB subunit Bdp1 rearranges the Pol III-specific subunits C37 and C34, thereby promoting DNA opening. The unwound DNA directly contacts both sides of the Pol III cleft. Topologically, the Pol III PIC resembles the Pol II PIC, whereas the Pol I PIC is more divergent. The structures presented unravel the molecular mechanisms underlying the first steps of Pol III transcription and also the general conserved mechanisms of gene transcription initiation.
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Subject
Saccharomyces cerevisiae
RNA Polymerase I
RNA Polymerase II
RNA Polymerase III
Transcription Factors, TFII
Transcription Factor TFIIIB
Saccharomyces cerevisiae Proteins
Protein Subunits
DNA
Cryoelectron Microscopy
Nucleic Acid Conformation
Templates, Genetic
Models, Molecular
Promoter Regions, Genetic
Transcription Initiation, Genetic
Research team
Structural Electron Microscopy
Vannini Group
Language
eng
Date accepted
2017-12-08
License start date
2018-01
Citation
Nature, 2018, 553 (7688), pp. 301 - 306
Publisher
NATURE PORTFOLIO