Mismatch repair proteins regulate heteroduplex formation during mitotic recombination in yeast.

Published

Journal Article

Mismatch repair (MMR) proteins actively inhibit recombination between diverged sequences in both prokaryotes and eukaryotes. Although the molecular basis of the antirecombination activity exerted by MMR proteins is unclear, it presumably involves the recognition of mismatches present in heteroduplex recombination intermediates. This recognition could be exerted during the initial stage of strand exchange, during the extension of heteroduplex DNA, or during the resolution of recombination intermediates. We previously used an assay system based on 350-bp inverted-repeat substrates to demonstrate that MMR proteins strongly inhibit mitotic recombination between diverged sequences in Saccharomyces cerevisiae. The assay system detects only those events that reverse the orientation of the region between the recombination substrates, which can occur as a result of either intrachromatid crossover or sister chromatid conversion. In the present study we sequenced the products of mitotic recombination between 94%-identical substrates in order to map gene conversion tracts in wild-type versus MMR-defective yeast strains. The sequence data indicate that (i) most recombination occurs via sister chromatid conversion and (ii) gene conversion tracts in an MMR-defective strain are significantly longer than those in an isogenic wild-type strain. The shortening of conversion tracts observed in a wild-type strain relative to an MMR-defective strain suggests that at least part of the antirecombination activity of MMR proteins derives from the blockage of heteroduplex extension in the presence of mismatches.

Full Text

Duke Authors

Cited Authors

  • Chen, W; Jinks-Robertson, S

Published Date

  • November 1998

Published In

Volume / Issue

  • 18 / 11

Start / End Page

  • 6525 - 6537

PubMed ID

  • 9774668

Pubmed Central ID

  • 9774668

International Standard Serial Number (ISSN)

  • 0270-7306

Digital Object Identifier (DOI)

  • 10.1128/mcb.18.11.6525

Language

  • eng

Conference Location

  • United States