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Replication restart: A pathway for (CTG)ยท(CAG) repeat deletion in Escherichia coli
- Source :
- Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis. 595:5-22
- Publication Year :
- 2006
- Publisher :
- Elsevier BV, 2006.
-
Abstract
- (CTG)n.(CAG)n repeats undergo deletion at a high rate in plasmids in Escherichia coli in a process that involves RecA and RecB. In addition, DNA replication fork progression can be blocked during synthesis of (CTG)n.(CAG)n repeats. Replication forks stalled at (CTG)n.(CAG)n repeats may be rescued by replication restart that involves recombination as well as enzymes involved in replication and DNA repair, and this process may be responsible for the high rate of repeat deletion in E. coli. To test this hypothesis (CAG)n.(CTG)n deletion rates were measured in several E. coli strains carrying mutations involved in replication restart. (CAG)n.(CTG)n deletion rates were decreased, relative to the rates in wild type cells, in strains containing mutations in priA, recG, ruvAB, and recO. Mutations in priB and priC resulted in small reductions in deletion rates. In a recF strain, rates were decreased when (CAG)n comprised the leading template strand, but rates were increased when (CTG)n comprised the leading template. Deletion rates were increased slightly in a recJ strain. The mutational spectra for most mutant strains were altered relative to those in parental strains. In addition, purified PriA and RecG proteins showed unexpected binding to single-stranded, duplex, and forked DNAs containing (CAG)n and/or (CTG)n loop-outs in various positions. The results presented are consistent with an interpretation that the high rates of trinucleotide repeat instability observed in E. coli result from the attempted restart of replication forks stalled at (CAG)n.(CTG)n repeats.
- Subjects :
- DNA Replication
DNA, Bacterial
congenital, hereditary, and neonatal diseases and abnormalities
DNA repair
Health, Toxicology and Mutagenesis
Molecular Sequence Data
Biology
medicine.disease_cause
Substrate Specificity
chemistry.chemical_compound
Plasmid
Escherichia coli
Genetics
medicine
Molecular Biology
Sequence Deletion
Adenosine Triphosphatases
RecBCD
Base Sequence
Models, Genetic
Escherichia coli Proteins
DNA Helicases
Wild type
DNA Replication Fork
Molecular biology
nervous system diseases
DNA-Binding Proteins
chemistry
Mutation
Nucleic Acid Conformation
Trinucleotide Repeat Expansion
Trinucleotide repeat expansion
DNA
Protein Binding
Subjects
Details
- ISSN :
- 00275107
- Volume :
- 595
- Database :
- OpenAIRE
- Journal :
- Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis
- Accession number :
- edsair.doi.dedup.....6596de17e6be6bc125ed73e9c8c2d8f6