Background: Slipped-DNAs are mutagenic intermediates in disease-causing trinucleotide repeat instability; their processing is not well understood. Results: MutLα is required to repair single short slip-outs, and enhances repair of clustered slipouts. Conclusion: Aberrant mismatch repair attempts on clustered slip-outs may cause repeat instability. Significance: This work has determined one of t...

In Xenopus egg extracts, DNA strand breaks (nicks) located 3' or 5' to a mismatch cause an overall 3-fold stimulation of the repair of the mismatch in circular heteroduplex DNA molecules. The increase in mismatch repair is almost entirely due to an increase in repair of the nicked strand, which is stimulated 5-fold. Repair synthesis is centered to the mismatch site, decreases symmetrically on b...

The MutS protein initiates DNA mismatch repair by recognizing mispaired and unpaired bases embedded in duplex DNA and activating endo- and exonucleases to remove the mismatch. Members of the MutS family also possess a conserved ATPase activity that belongs to the ATP binding cassette (ABC) superfamily. Here we report the crystal structure of a ternary complex of MutS-DNA-ADP and assays of initi...

We have previously reported that the Escherichia coli mutator strain mutD5 was defective in the correction of bacteriophage M13mp2 heteroduplex DNA containing a T.G mismatch. Here, this defect was further investigated with regard to its interaction with the mutHLS pathway of mismatch repair. A set of 15 different M13mp2 heteroduplexes was used to measure the mismatch-repair capability of wild-t...

The occurrence of mutator phenotypes among laboratory-generated and clinical levofloxacin-resistant strains of Streptococcus pneumoniae was determined using fluctuation analysis. The in vitro selection for levofloxacin-resistant mutants of strain D39, each with point mutations in both gyrA and parC or parE, was not associated with a significant change in the mutation rate. Two of eight clinical...

Title of Document: DNA MISMATCH REPAIR AND RESPONSE TO OXIDATIVE STRESS IN THE EXTREMELY HALOPHILIC ARCHAEON HALOBACTERIUM SP. STRAIN NRC-1 Courtney Rae Busch, Doctor of Philosophy, 2008 Directed By: Assistant Professor Dr. Jocelyne DiRuggiero, Department of Cell Biology and Molecular Genetics Halobacterium is an extremely halophilic archaeon that has homologs of the key proteins, MutS and MutL...

Background: Germline mutations in the mismatch repair (MMR) genes hMLH1 and hMSH2 can cause hereditary non-polyposis colorectal cancer (HNPCC). However, the functional in vitro analysis of hMLH1 and hMSH2 mutations remains difficult. Aims: To establish an in vitro method for the functional characterisation of hMLH1 and hMSH2 mutations. Methods: hMLH1 and hMSH2 wild type (wt) genes and several m...

Background: Infertility is increasingly recognized as a major health problem. Meiotic genes are very important candidates for genes contributing to female and male infertility. Mammalian MutL homologues have dual roles in DNA mismatch repair (MMR) after replication errors and meiotic reciprocal recombination. There are four MutL homologues in eukaryotes that mutations of three of them (Mlh1, Ml...