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Artificial RNA Polymerase II Elongation Complexes for Dissecting Co-transcriptional RNA Processing Events
Published on: May 13, 2019
The RNA polymerase II trigger loop functions in substrate selection and is directly targeted by alpha-amanitin
Craig D Kaplan1, Karl-Magnus Larsson, Roger D Kornberg
1Department of Structural Biology, Stanford University, Stanford, CA 94305, USA. cdkaplan@stanford.edu
Molecular Cell
|June 10, 2008
Summary
The Trigger Loop (TL) in RNA Polymerase II (Pol II) is crucial for selecting substrates during transcription. Mutations in the TL and alpha-amanitin inhibition both impact enzyme fidelity and substrate usage.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- The Trigger Loop (TL) is a mobile element in multisubunit RNA polymerases.
- Previous studies suggest the TL is vital for catalysis and a target for antibiotics.
Purpose of the Study:
- To investigate the role of the Saccharomyces cerevisiae RNA Polymerase II (Pol II) TL in substrate selection.
- To explore the functional interaction between the TL and the antibiotic alpha-amanitin.
Main Methods:
- Amino acid substitutions within the Pol II TL were introduced.
- The effects of these substitutions and alpha-amanitin inhibition on transcription were analyzed.
- A crystal structure of alpha-amanitin-bound Pol II was rerefined.
Main Results:
- Substitutions in the Pol II TL altered substrate usage and enzyme fidelity.
- His1085 substitution in the TL conferred significant resistance to alpha-amanitin.
- Rerefined crystal structure supports a direct interaction between His1085 and alpha-amanitin.
Conclusions:
- The Pol II TL plays a key role in substrate selection during transcription.
- Alpha-amanitin directly interferes with the TL, affecting elongation and substrate selectivity.
- His1085 is critical for alpha-amanitin sensitivity, highlighting a specific inhibitory mechanism.
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