Related Experiment Video
Updated: Jun 18, 2026
07:44
High-throughput Purification of Affinity-tagged Recombinant Proteins
Published on: August 26, 2012
Structure-function analysis of RNA polymerases I and III.
Michel Werner1, Pierre Thuriaux, Julie Soutourina
1CEA, iRCM, F-91057 Evry Cedex, France. michel.werner@cea.fr
Current Opinion in Structural Biology
|November 10, 2009
Summary
New research compares yeast RNA polymerases I and III structures, revealing unique subunits and functions. Surprisingly, a Pol II factor also aids Pol III transcription, highlighting conserved mechanisms in eukaryotic gene regulation.
Area of Science:
- Molecular Biology
- Structural Biology
- Genetics
Background:
- Eukaryotic nuclear RNA polymerases (Pol I, Pol II, Pol III) transcribe different sets of genes.
- Structural and functional differences, particularly unique subunits, distinguish these polymerases.
- Understanding these differences is key to comprehending gene regulation.
Purpose of the Study:
- To compare the structures of yeast RNA polymerase I (Pol I) and Pol III.
- To elucidate the functional roles of unique subunits in Pol I and Pol III transcription.
- To investigate the involvement of transcription factors across different RNA polymerases.
Main Methods:
- X-ray crystal analysis
- Electron microscopy
- Homology modeling
Main Results:
- Detailed structures of yeast Pol I and Pol III were elucidated, enabling direct comparison.
- Unique subunits specific to Pol I and Pol III were identified and their locations mapped.
- The transcription cleavage factor TFIIS, known for Pol II, was found to play a role in Pol III transcription, despite Pol I and III having intrinsic RNA cleavage activity.
Conclusions:
- Structural comparisons highlight key differences, particularly unique subunits, in eukaryotic RNA polymerases.
- The functions of these unique subunits in transcription initiation, elongation, termination, and reinitiation are suggested.
- The unexpected role of the TFIIS Pol II cleavage stimulation factor in Pol III transcription suggests conserved regulatory mechanisms.
Related Concept Videos
00:58Eukaryotic RNA Polymerases
RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...
All three eukaryotic RNAPs require specific transcription factors, of which the...
00:58Eukaryotic RNA Polymerases
RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...
All three eukaryotic RNAPs require specific transcription factors, of which the...
01:47Transcription Initiation
Initiation is the first step of transcription in eukaryotes. Prokaryotic RNA Polymerase (RNAP) can bind to the template DNA and start transcribing. On the other hand, transcription in eukaryotes requires additional proteins, called transcription factors, to first bind to the promoter region in the DNA template. This binding helps recruit the specific RNAP that can assemble on the DNA and start transcription.
The promoters and enhancers and their accessory proteins allow tight regulation of...
The promoters and enhancers and their accessory proteins allow tight regulation of...
00:43Bacterial RNA Polymerase
Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
00:43Bacterial RNA Polymerase
Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
02:36RNA Polymerase II Accessory Proteins
Proteins that regulate transcription can do so either via direct contact with RNA Polymerase or through indirect interactions facilitated by adaptors, mediators, histone-modifying proteins, and nucleosome remodelers. Direct interactions to activate transcription is seen in bacteria as well as in some eukaryotic genes. In these cases, upstream activation sequences are adjacent to the promoters, and the activator proteins interact directly with the transcriptional machinery. For example, in...