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Cryo-negative staining reveals conformational flexibility within yeast RNA polymerase I
Sacha De Carlo1, Christophe Carles, Michel Riva
1Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, 1 rue Laurent Fries, BP163, F-67404 Illkirch Cedex, C.U. de Strasbourg, France. decarlo@titus.u-strasbg.fr
Journal of Molecular Biology
|June 12, 2003
Summary
Researchers visualized yeast RNA polymerase I (RNA Pol I) structure using cryo-electron microscopy. They identified conformational flexibility and a novel protrusion, offering insights into enzyme regulation and DNA binding.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- Yeast RNA polymerase I (RNA Pol I) is crucial for ribosomal DNA transcription.
- Understanding RNA Pol I structure is key to deciphering its regulatory mechanisms.
Purpose of the Study:
- To determine the high-resolution structure of yeast RNA Pol I.
- To investigate its conformational flexibility and identify novel structural features.
Main Methods:
- Cryo-negative staining electron microscopy was used to image isolated RNA Pol I molecules.
- A novel strategy was developed to sort heterogeneous data into distinct conformations.
- 3D reconstruction and model fitting were performed to achieve 1.8 nm resolution.
Main Results:
- A structural model of yeast RNA Pol I was generated, fitting well with RNA Pol II.
- Conformational flexibility, specifically in the wall/flap domain, was observed, impacting DNA-binding groove accessibility.
- A novel protrusion, not seen in previous models or atomic structures, was identified.
Conclusions:
- The identified conformational change likely plays a role in regulating transcription initiation and elongation.
- The novel protrusion's presence suggests a previously unrecognized structural element of RNA Pol I.
- Molybdenum compounds in the DNA-binding groove may reflect the molecule's surface charge distribution.