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Published on: October 4, 2018
Structure of human mitochondrial RNA polymerase
Rieke Ringel1, Marina Sologub, Yaroslav I Morozov
1Gene Center and Department of Biochemistry, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
Nature
|September 28, 2011
Summary
Mitochondrial RNA polymerase (mtRNAP) requires TFAM and TFB2M for transcription initiation. The X-ray structure reveals mtRNAP
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Mitochondrial transcription relies on a single-subunit RNA polymerase (mtRNAP).
- mtRNAP shares distant ancestry with bacteriophage T7 RNA polymerase.
- Unlike T7 RNAP, mtRNAP needs transcription factors TFAM and TFB2M for promoter binding and DNA melting.
Purpose of the Study:
- To elucidate the structural basis of human mtRNAP function.
- To understand the roles of TFAM and TFB2M in mitochondrial transcription initiation.
- To provide insights into the evolution of mtRNAP.
Main Methods:
- X-ray crystallography of human mtRNAP at 2.5 Å resolution.
- Site-directed mutagenesis to probe functional domains.
- Analysis of transcription assays.
Main Results:
- The structure reveals a T7-like catalytic domain, a novel pentatricopeptide repeat domain, and a repositioned fingers domain.
- The pentatricopeptide repeat domain sequesters a DNA-binding loop, explaining TFAM's role in promoter binding.
- Repositioned domains explain TFB2M's necessity for promoter melting.
Conclusions:
- The structure explains how mtRNAP lost intrinsic promoter binding and melting capabilities.
- Evolutionary acquisition of TFAM and TFB2M enabled mitochondrial gene regulation.
- These findings offer new avenues for studying mitochondrial transcription mechanisms.
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