Physical interaction between components of DNA mismatch repair and nucleotide excision repair

Abstract

Nucleotide excision repair (NER) and DNA mismatch repair are required for some common processes although the biochemical basis for this requirement is unknown. Saccharomyces cerevisiae RAD14 was identified in a two-hybrid screen using MSH2 as ''bait,'' and pairwise interactions between MSH2 and RAD1, RAD2, RAD3, RAD10, RAD14, and RAD25 subsequently were demonstrated by two-hybrid analysis. MSH2 coimmunoprecipitated specifically with epitope-tagged versions of RAD2, RAD10, RAD14, and RAD25. MSH2 and RAD10 were found to interact in msh3 msh6 and mlh1 pms1 double mutants, suggesting a direct interaction with MSH2. Mutations in MSH2 increased the UV sensitivity of NER-deficient yeast strains, and msh2 mutations were epistatic to the mutator phenotype observed in NER-deficient strains. These data suggest that MSH2 and possibly other components of DNA mismatch repair exist in a complex with NER proteins, providing a biochemical and genetical basis for these proteins to function in common processes.Eukaryotes contain a DNA mismatch repair (MMR) system involving proteins related to the bacterial MutS and MutL proteins (for a review see ref. 1). The eukaryotic MMR system is more complex than the bacterial system. Instead of involving a single MutS-related protein, eukaryotic MMR involves two different heterodimeric complexes of MutS-related proteins, MSH2-MSH3 and MSH2-MSH6, that each have different mispair recognition specificity (1-7). Similarly, instead of a single MutL-related protein, eukaryotic MMR also involves a heterodimeric complex of two MutL-related proteins, MLH1-PMS1 (PMS2 in humans) (8,9). Initial characterization of these pathways concentrated on their function in correcting mispaired bases resulting from DNA replication errors and the formation of heteroduplex recombination intermediates. Subsequent studies have suggested that MMR proteins may play more diverse roles in DNA metabolism.MMR plays roles in genetic recombination beyond the repair of mispaired bases in recombination intermediates. MMR appears to regulate the extent of formation of heteroduplex tracts during recombination (10-12), possibly by regulating the resolution of Holliday junctions (11). MMR also suppresses recombination between divergent sequences (13-16), a process that may be similar to the proposed regulation of heteroduplex tract formation. The MSH2 and MSH3 proteins also act in recombination between duplicated DNA sequences (17, 18) and have been implicated in the removal of nonhomologous DNA strands greater than 30 bases long at the ends of recombining segments (19). This reaction involves the nucleotide excision repair (NER) complex 21). It is unclear how MMR proteins function in these reactions; however, the ability of MSH2 and the MSH2-MSH6 complex to bind to Holliday junctions and branched DNA structures (ref. 22 and G. T. Marsischky, S. Lee, J. Griffith, and R.D.K., unpublished results) suggest they could bind to branched DNA structures and either target resolution enzymes and endonucleases to these structures or al...

DNA mismatch repair: Molecular mechanism, cancer, and ageing

“…Msh2 −/− mice exhibit an increased predisposition to skin cancer in response to UVB exposure that is enhanced when mice are additionally defective for the NER Xpc gene (Meira et al, 2002). Interactions between scMsh2 and the NER proteins Rad2, Rad10, and Rad14 have been observed in co-immunoprecipitation experiments (Bertrand et al, 1998), and loss of MMR in human cells leads to a deficiency in transcription-coupled NER (Mellon et al, 1996). These and other studies point to a still poorly defined interaction between elements of these two excision repair pathways.…”

Human cells bearing homozygous mutations in the DNA mismatch repair genes hMLH1 or hMSH2 are fully proficient in transcription-coupled nucleotide excision repair

“…Thirdly, in strong support of the above, but using a different type of strand-specific DNA repair assay that measures the post-excision (gap-filling) steps of NER, it was subsequently demonstrated (i) that both hMLH1-and hMSH2-deficient human adenocarcinoma cells are impaired in TCNER of UV-induced CPDs at the active metallothionein locus (Leadon and Avrutskaya, 1997), and (ii) that hMSH2-(but not hMLH1-) deficient cells (Leadon and Avrutskaya, 1997) as well as MMR-deficient yeast (Leadon and Avrutskaya, 1998) are defective in transcriptioncoupled repair of oxidative DNA damage (presumably via base excision repair rather than nucleotide excision repair). Finally, a number of in vitro studies, e.g., including those based on the yeast S. Cerevisiae (Bertrand et al, 1998;Fleck et al, 1999;Kirkpatrick and Petes, 1997) as well as human cells (Wang et al, 1999), have revealed physical and functional interactions between components of the MMR and NER pathways.…”

Molecular Mechanisms of Mismatch Repair Genes in Cancer A Brief Review

“…Conclusions and future perspective corrects lesions in the transcription template strand of RNA polymerase II-transcribed genes [65.] Although the mechanistic details of the involvement of MMR proteins in TCR are not known, specific interactions between MSH2 and NER proteins have been detected in yeast [66]. MSH2 contributes to the recognition of a stalled RNA polymerase on the transcription template strand at sites of DNA damage.…”