Format

Send to

Choose Destination
PLoS Genet. 2014 Sep 4;10(9):e1004583. doi: 10.1371/journal.pgen.1004583. eCollection 2014 Sep.

Eliminating both canonical and short-patch mismatch repair in Drosophila melanogaster suggests a new meiotic recombination model.

Author information

1
Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America; Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America.
2
Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America; Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America.

Abstract

In most meiotic systems, recombination is essential to form connections between homologs that ensure their accurate segregation from one another. Meiotic recombination is initiated by DNA double-strand breaks that are repaired using the homologous chromosome as a template. Studies of recombination in budding yeast have led to a model in which most early repair intermediates are disassembled to produce noncrossovers. Selected repair events are stabilized so they can proceed to form double-Holliday junction (dHJ) intermediates, which are subsequently resolved into crossovers. This model is supported in yeast by physical isolation of recombination intermediates, but the extent to which it pertains to animals is unknown. We sought to test this model in Drosophila melanogaster by analyzing patterns of heteroduplex DNA (hDNA) in recombination products. Previous attempts to do this have relied on knocking out the canonical mismatch repair (MMR) pathway, but in both yeast and Drosophila the resulting recombination products are complex and difficult to interpret. We show that, in Drosophila, this complexity results from a secondary, short-patch MMR pathway that requires nucleotide excision repair. Knocking out both canonical and short-patch MMR reveals hDNA patterns that reveal that many noncrossovers arise after both ends of the break have engaged with the homolog. Patterns of hDNA in crossovers could be explained by biased resolution of a dHJ; however, considering the noncrossover and crossover results together suggests a model in which a two-end engagement intermediate with unligated HJs can be disassembled by a helicase to a produce noncrossover or nicked by a nuclease to produce a crossover. While some aspects of this model are similar to the model from budding yeast, production of both noncrossovers and crossovers from a single, late intermediate is a fundamental difference that has important implications for crossover control.

PMID:
25188408
PMCID:
PMC4154643
DOI:
10.1371/journal.pgen.1004583
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Public Library of Science Icon for PubMed Central
Loading ...
Support Center