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The archaeal exosome core is a hexameric ring structure with three catalytic subunits
Esben Lorentzen1, Pamela Walter, Sebastien Fribourg
1European Molecular Biology Laboratory, Heidelberg, Germany.
Nature Structural & Molecular Biology
|June 14, 2005
Summary
The crystal structure of the archaeal exosome reveals a hexameric ring complex essential for RNA processing. This structure provides insights into the evolution of RNA degradation machinery across life.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- The exosome is a crucial 3' to 5' exoribonuclease complex responsible for RNA processing.
- Understanding the exosome's structure is key to elucidating RNA degradation pathways.
Purpose of the Study:
- To determine the crystal structure of the Sulfolobus solfataricus exosome's core complex.
- To investigate the structural basis of its exoribonuclease activity.
Main Methods:
- X-ray crystallography was used to determine the structure at 2.8 A resolution.
- Structure-guided mutagenesis was employed to identify active sites.
Main Results:
- The structure revealed a hexameric ring composed of Rrp41-Rrp42 heterodimers, each with an RNase PH fold.
- Catalytic activity was localized to the Rrp41 subunits, while Rrp42 contributed to active site formation.
- High structural similarity to bacterial PNPase and sequence similarity to eukaryotic exosomes were observed.
Conclusions:
- The archaeal exosome structure provides a model for RNA degradation machinery across all domains of life.
- The findings highlight a conserved mechanism for RNA processing and degradation.