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RNA synthesis in a cage--structural studies of reovirus polymerase lambda3
Yizhi Tao1, Diane L Farsetta, Max L Nibert
1Howard Hughes Medical Institute, Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
Cell
|December 5, 2002
Summary
The reovirus lambda3 polymerase crystal structure reveals a unique "caged" design. This structure explains how the enzyme transcribes double-stranded RNA (dsRNA) genomes and suggests a template retention mechanism for efficient RNA polymerization.
Area of Science:
- Virology
- Structural Biology
- Molecular Biology
Background:
- Reovirus polymerase functions within a protein capsid to transcribe dsRNA genomes.
- Understanding viral polymerase structure is key to viral replication mechanisms.
Purpose of the Study:
- To determine the crystal structure of the reovirus lambda3 polymerase.
- To elucidate the mechanism of RNA polymerization within the viral capsid.
Main Methods:
- X-ray crystallography at 2.5 A resolution.
- Structural analysis of the reovirus lambda3 polymerase.
Main Results:
- The lambda3 polymerase possesses a fingers-palm-thumb core with surrounding elaborations, forming a cage-like structure.
- Four channels lead to the catalytic site, enabling visualization of RNA polymerization within crystals.
- A 5' cap binding site suggests a template retention mechanism facilitating RNA synthesis.
Conclusions:
- The reovirus polymerase's unique structure facilitates efficient transcription of dsRNA genomes.
- The identified template retention mechanism is crucial for the enzyme's function.
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