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Replication slippage may cause parallel evolution in the secondary structures of mitochondrial transfer RNAs
J R Macey1, A Larson, N B Ananjeva
1Department of Biology, Washington University, St. Louis, Missouri 63130, USA.
Molecular Biology and Evolution
|January 1, 1997
Summary
Mitochondrial cysteine tRNAs in reptiles show a variable D-stem. Eight parallel losses of this stem, likely due to replication slippage, explain alterations in reptile mitochondrial tRNA structure.
Area of Science:
- Evolutionary biology
- Molecular biology
- Genetics
Background:
- The dihydrouridine (D) stem in mitochondrial cysteine tRNA exhibits significant variability across lepidosaurian reptiles.
- This variability suggests underlying evolutionary pressures or mechanisms affecting tRNA structure in this group.
Purpose of the Study:
- To investigate the evolutionary history and mechanisms behind the D-stem's variability in lepidosaurian mitochondrial cysteine tRNA.
- To determine if observed D-stem losses are reversible or represent fixed evolutionary changes.
Main Methods:
- Phylogenetic analysis of cysteine tRNA gene sequences from various lepidosaurian reptiles.
- Comparative sequence analysis to identify patterns of D-stem loss and D-arm replacement loops.
- Examination of specific clades, such as Acrodonta, for evidence of D-stem reversal.
Main Results:
- Identified eight instances of parallel D-stem losses in mitochondrial cysteine tRNA across lepidosaurian lineages.
- Observed D-arm replacement loops resulting from these losses.
- Found no evidence of D-stem reversal within the monophyletic Acrodonta group.
- Identified repeats within cysteine tRNAs containing D-arm replacement loops, suggesting replication slippage mechanisms.
Conclusions:
- Replication slippage, including slipped-strand mispairing and direct replication slippage, provides a plausible explanation for D-stem loss in lepidosaurian mitochondrial cysteine tRNA.
- These mechanisms may be general drivers of secondary structure alterations in mitochondrial tRNAs across various lineages.