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Structure of wild-type yeast RNA polymerase II and location of Rpb4 and Rpb7
G J Jensen1, G Meredith, D A Bushnell
1Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
The EMBO Journal
|May 26, 1998
Summary
The yeast RNA polymerase II structure reveals Rpb4 and Rpb7 subunits stabilize DNA binding. These subunits are crucial for promoter transcription and cellular stress response.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- RNA polymerase II (Pol II) is essential for gene transcription in eukaryotes.
- Understanding the structural basis of Pol II function is key to deciphering gene regulation.
- Subunits Rpb4 and Rpb7's roles in Pol II structure and function remain incompletely understood.
Purpose of the Study:
- To determine the three-dimensional structure of wild-type yeast RNA polymerase II.
- To elucidate the structural contribution of subunits Rpb4 and Rpb7.
- To investigate the functional role of Rpb4 and Rpb7 in transcription initiation.
Main Methods:
- Three-dimensional structure determination of yeast RNA polymerase II using cryo-electron microscopy at 24 Å resolution.
- Difference mapping to compare wild-type Pol II with a Pol II lacking Rpb4 and Rpb7.
- Surface plasmon resonance (SPR) to assess the stability of pre-initiation complexes.
Main Results:
- The structure revealed Rpb4 and Rpb7 subunits form part of the DNA-binding cleft floor.
- A slight inward movement of the surrounding protein domain was observed upon Rpb4/Rpb7 binding.
- SPR measurements demonstrated Rpb4 and Rpb7 stabilize minimal pre-initiation complexes.
Conclusions:
- Rpb4 and Rpb7 subunits are integral to the structural integrity of the RNA polymerase II active center cleft.
- These subunits likely play a role in coupling DNA entry to cleft closure during transcription initiation.
- The findings explain the necessity of Rpb4 and Rpb7 for promoter-specific transcription and in vivo stress response.