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Updated: Aug 7, 2026
10:59
Artificial RNA Polymerase II Elongation Complexes for Dissecting Co-transcriptional RNA Processing Events
Published on: May 13, 2019
The conserved AAUAAA hexamer of the poly(A) signal can act alone to trigger a stable decrease in RNA polymerase II
Anita Nag1, Kazim Narsinh, Amir Kazerouninia
1Department of Chemistry and Biochemistry, University of California at Los Angeles, CA 90095-1569, USA.
RNA (New York, N.Y.)
|June 16, 2006
Summary
The AAUAAA hexamer, not the G/U-rich region, is essential for pausing RNA polymerase II during transcription. This pause, initiated by the hexamer, influences downstream events like 3'-end processing and termination.
Area of Science:
- Molecular Biology
- Gene Regulation
- Biochemistry
Background:
- The polyadenylation (poly(A)) signal is crucial for 3'-end processing and transcription termination by RNA polymerase II.
- Poly(A) signals regulate transcription by inducing polymerase pausing and subsequent termination.
- The poly(A) signal comprises distinct sequence elements, including the AAUAAA hexamer and a G/U-rich region.
Purpose of the Study:
- To investigate the specific roles of the AAUAAA hexamer and the G/U-rich region of the poly(A) signal in RNA polymerase II pausing and termination.
- To determine which components of the poly(A) signal are necessary for poly(A)-dependent pausing in vivo and in vitro.
- To elucidate the mechanism by which the poly(A) signal controls transcription progression.
Main Methods:
- In vivo transcription assays to observe RNA polymerase II behavior.
- In vitro transcription assays to study pausing mechanisms.
- Mutational analysis of the poly(A) signal elements (AAUAAA hexamer and G/U-rich region).
- Investigating the roles of CstF and the polymerase CTD in pausing.
Main Results:
- The G/U-rich region is required for termination in vivo but not for poly(A)-dependent pausing, either in vivo or in vitro.
- The AAUAAA hexamer is the sole essential component of the poly(A) signal for inducing polymerase pausing.
- Pausing induced by the hexamer has a long-lasting effect, impacting polymerases over 1 kb downstream.
- CstF and the polymerase CTD are not required for pausing, despite recognizing the G/U-rich element.
Conclusions:
- The AAUAAA hexamer acts as the primary determinant for RNA polymerase II pausing.
- The G/U-rich region functions independently of the hexamer in transcription termination.
- The hexamer's pausing effect may precede and facilitate subsequent 3'-end processing and termination events.
- The findings reveal a distinct mechanism for polymerase pausing mediated by the AAUAAA hexamer, separate from termination signals.
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