Rad22Rad52-dependent repair of ribosomal DNA repeats cleaved by Slx1-Slx4 endonuclease.
Slx1 and Slx4 are subunits of a structure-specific DNA endonuclease that is found in Saccharomyces cerevisiae, Schizosaccharomyces pombe, and other eukaryotic species. It is thought to initiate recombination events or process recombination structures that occur during the replication of the tandem repeats of the ribosomal DNA (rDNA) locus. Here, we present evidence that fission yeast Slx1-Slx4 initiates homologous recombination events in the rDNA repeats that are processed by a mechanism that requires Rad22 (Rad52 homologue) but not Rhp51 (Rad51 homologue). Slx1 is required to generate approximately 50% of the spontaneous Rad22 DNA repair foci that occur in cycling cells. Most of these foci colocalize with the nucleolus, which contains the rDNA repeats. The increased fork pausing at the replication fork barriers in the rDNA repeats in a strain that lacks Rqh1 DNA helicase is further increased by expression of a dominant negative form of Slx1. These data suggest that Slx1-Slx4 cleaves paused replication forks in the rDNA, leading to Rad22-dependent homologous recombination that is used to maintain rDNA copy number.
Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Stéphane
S
Coulon
Eishi
E
Noguchi
Chiaki
C
Noguchi
Li-Lin
LL
Du
Toru M
TM
Nakamura
Paul
P
Russell
D002467:Cell Nucleus / Q000737:chemistry; D004260:DNA Repair / Q000235:genetics; D004261:DNA Replication; D004275:DNA, Ribosomal / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D051721:Rad52 DNA Repair and Recombination Protein / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D012568:Schizosaccharomyces / Q000737:chemistry / Q000201:enzymology / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D020080:Tandem Repeat Sequences
D004275:DNA, Ribosomal; D004268:DNA-Binding Proteins; D051721:Rad52 DNA Repair and Recombination Protein; D029702:Schizosaccharomyces pombe Proteins; C085412:rad52 protein, S pombe; D004706:Endodeoxyribonucleases; C511271:Slx1 protein, S pombe; C511272:Slx4 protein, S pombe