Trinucleotide repeat expansion disorders (TRED) are caused by genomic expansions of trinucleotide repeats, such as CTG and CAG. These expanded repeats are unstable in germline and somatic cells, with potential consequences for disease severity. Previous studies have demonstrated the involvement of DNA repair proteins in repeat instability, although the key factors affecting large repeat expansi...

abstract   background: the polymorphic variants at codon 72 of the p53 gene, encoding either proline or arginine at residue 72, produce marked change in the structure of p53. from the evidence that the dnamismatch repair system and p53 interact to maintain genomic integrity, we hypothesized that the codon 72 variation may influence the prevalence of microsatellite instability a feature of malig...

A direct repeat recombination assay between SUP4 heteroalleles detects unrepaired heteroduplex DNA (hDNA) as sectored colonies. The frequency of unrepaired heteroduplex is dependent on the mismatch and is highest in a construct that generates C:C or G:G mispairs and lowest in one that generates T:G or C:A mispairs. In addition, unrepaired hDNA increases for all mismatches tested in pms1 mismatc...

Mutations are introduced into rearranged Ig variable genes at a frequency of 10(-2) mutations per base pair by an unknown mechanism. Assuming that DNA repair pathways generate or remove mutations, the frequency and pattern of mutation will be different in variable genes from mice defective in repair. Therefore, hypermutation was studied in mice deficient for either the DNA nucleotide excision r...

In yeast meiotic recombination, alleles used as genetic markers fall into two classes as regards their fate when incorporated into heteroduplex DNA. Normal alleles are those that form heteroduplexes that are nearly always recognized and corrected by the mismatch repair system operating in meiosis. High PMS (postmeiotic segregation) alleles form heteroduplexes that are inefficiently mismatch rep...

When gene conversion is initiated by a double-strand break (DSB), any nonhomologous DNA that may be present at the ends must be removed before new DNA synthesis can be initiated. In Saccharomyces cerevisiae, removal of nonhomologous ends depends not only on the nucleotide excision repair endonuclease Rad1/Rad10 but also on Msh2 and Msh3, two proteins that are required to correct mismatched bp. ...

To improve replication fidelity, mismatch repair (MMR) must detect non-Watson-Crick base pairs and direct their repair to the nascent DNA strand. Eukaryotic MMR in vitro requires pre-existing strand discontinuities for initiation; consequently, it has been postulated that MMR in vivo initiates at Okazaki fragment termini in the lagging strand and at nicks generated in the leading strand by the ...