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Updated: Jul 1, 2026
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Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase
Published on: April 30, 2010
Dynamic positioning of Rpc34 winged helix in RNA polymerase III elongation complex for its stability with
Jheng-Syong Wu1, Yu-Chun Lin2, Yi-Yu Wei2
1Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.
Summary
The Rpc34-WH2 domain of RNA polymerase III dynamically moves within the transcription complex, acting as a mobile regulator. This study reveals its distinct positional states during RNA synthesis.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- RNA polymerase III (Pol III) synthesizes short RNAs using unique TFIIE/TFIIF-like subcomplexes.
- The Rpc34 subunit's winged helix domain (WH2) role in Pol III elongation is unclear due to its absence in cryo-EM structures.
Purpose of the Study:
- To investigate the dynamics and positioning of the Rpc34-WH2 domain in Pol III elongation complexes (ECs).
- To develop a robust method for site-specific labeling in large protein assemblies for smFRET studies.
Main Methods:
- Utilized single-molecule Förster resonance energy transfer (smFRET) and nano-positioning triangulation.
- Developed a bio-orthogonal chemical biology framework for site-specific unnatural amino acid incorporation.
- Employed azido-carrying unnatural amino acids and thiol-capping for precise labeling.
Main Results:
- Rpc34-WH2 dynamically transitions among three distinct positions within the DNA-binding cleft.
- One identified position matches its location in the preinitiation complex, suggesting conserved interactions.
- Established Rpc34-WH2 as a mobile regulatory element interacting transiently with the Pol III EC.
Conclusions:
- Rpc34-WH2 is a mobile regulatory element in Pol III ECs, engaging through transient interactions.
- The developed bio-orthogonal labeling strategy is a generalizable method for studying large protein complexes with smFRET.
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