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Accurate and efficient insertional RNA editing in isolated Physarum mitochondria
L M Visomirski-Robic1, J M Gott
1Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
RNA (New York, N.Y.)
|September 1, 1995
Summary
RNA editing in Physarum polycephalum mitochondria precisely inserts nucleotides. This study demonstrates accurate nucleotide insertion, suggesting base changes may not involve deletion-insertion mechanisms.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- RNA editing modifies RNA sequences post-transcriptionally.
- Mitochondrial RNAs in Physarum polycephalum undergo nucleotide insertions and base changes.
- The mechanisms of these RNA editing events remain unclear.
Purpose of the Study:
- To investigate the mechanism of RNA editing in isolated Physarum polycephalum mitochondria.
- To determine if nucleotide insertions and base changes occur in a cell-free system.
- To elucidate the processing of mitochondrial RNAs.
Main Methods:
- Development of an isolated mitochondrial system for RNA synthesis.
- Incorporation of exogenously supplied nucleotides into mitochondrial RNAs.
- Analysis using S1 nuclease protection, nearest neighbor, and RNase T1 fingerprinting.
Main Results:
- Isolated mitochondria accurately and efficiently incorporated mono- and dinucleotides into RNAs.
- Newly synthesized mitochondrial RNAs demonstrated faithful nucleotide insertion.
- Cytidine (C) to uridine (U) base changes were not observed in the isolated system.
Conclusions:
- Direct evidence supports accurate nucleotide insertion during mitochondrial RNA editing in Physarum.
- The observed C to U base changes in vivo are unlikely to result from a deletion-insertion mechanism.
- This study provides a novel in vitro system for studying mitochondrial RNA editing.