Meiotic recombination involving heterozygous large insertions in Saccharomyces cerevisiae: formation and repair of large, unpaired DNA loops.
Meiotic recombination in Saccharomyces cerevisiae involves the formation of heteroduplexes, duplexes containing DNA strands derived from two different homologues. If the two strands of DNA differ by an insertion or deletion, the heteroduplex will contain an unpaired DNA loop. We found that unpaired loops as large as 5.6 kb can be accommodated within a heteroduplex. Repair of these loops involved the nucleotide excision repair (NER) enzymes Rad1p and Rad10p and the mismatch repair (MMR) proteins Msh2p and Msh3p, but not several other NER (Rad2p and Rad14p) and MMR (Msh4p, Msh6p, Mlh1p, Pms1p, Mlh2p, Mlh3p) proteins. Heteroduplexes were also formed with DNA strands derived from alleles containing two different large insertions, creating a large "bubble"; repair of this substrate was dependent on Rad1p. Although meiotic recombination events in yeast are initiated by double-strand DNA breaks (DSBs), we showed that DSBs occurring within heterozygous insertions do not stimulate interhomologue recombination.
Kearney
H M
HM
Department of Biology, Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280, USA.
Kirkpatrick
D T
DT
Gerton
J L
JL
Petes
T D
TD
D020137:Base Pair Mismatch; D015139:Blotting, Southern; D004247:DNA / Q000737:chemistry*; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000378:metabolism; D004720:Endonucleases / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D006579:Heterozygote; D008540:Meiosis; D008957:Models, Genetic; D051718:MutS Homolog 2 Protein; D000074081:MutS Homolog 3 Protein; D009690:Nucleic Acid Conformation; D009692:Nucleic Acid Heteroduplexes / Q000737:chemistry; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D015719:Single-Strand Specific DNA and RNA Endonucleases
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C081696:MSH3 protein, S cerevisiae; D000074081:MutS Homolog 3 Protein; D009692:Nucleic Acid Heteroduplexes; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D004720:Endonucleases; C069266:RAD1 protein, S cerevisiae; C064162:RAD10 protein, S cerevisiae; D015719:Single-Strand Specific DNA and RNA Endonucleases; C489751:MSH2 protein, S cerevisiae; D051718:MutS Homolog 2 Protein; D045643:DNA Repair Enzymes