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Inverted DNA repeats: a source of eukaryotic genomic instability
D A Gordenin1, K S Lobachev, N P Degtyareva
1Department of Genetics, St. Petersburg State University, Russia.
Molecular and Cellular Biology
|September 1, 1993
Summary
Long inverted DNA repeats cause genetic instability and deletions in yeast, primarily through replication errors. These repeats also promote homologous recombination, highlighting their significant impact on eukaryotic genomes.
Area of Science:
- Molecular Biology
- Genetics
- Yeast Genetics
Background:
- Inverted DNA repeats are known genetic instability sources in prokaryotes.
- Their role in eukaryotic genetic instability remains less understood.
Purpose of the Study:
- To investigate the effects of long inverted DNA repeats on genetic instability in yeast (Saccharomyces cerevisiae).
- To elucidate the mechanisms underlying repeat-induced deletions and recombination.
Main Methods:
- Utilized bacterial transposon Tn5 and its derivatives in yeast.
- Analyzed deletion formation and homologous recombination events.
- Investigated the role of DNA polymerase delta (pol3) mutation.
- Examined intra- and interchromosomal recombination.
Main Results:
- Long inverted repeats induce genetic instability and deletions in yeast.
- Replication is a major factor in deletion formation, stimulated by pol3 mutation.
- Deletions often result from imprecise excision between small repeats, forming unstable quasipalindromes.
- Repeats act as hot spots for intra- and interchromosomal recombination.
- Breakpoints cluster near the ends of inverted repeats.
Conclusions:
- Long inverted repeats contribute significantly to genetic instability in yeast.
- Altered replication at the base of the inverted repeat stem likely drives both deletion and recombination processes.