Patching broken chromosomes with extranuclear cellular DNA.
Chromosomal double-strand breaks (DSBs) can be repaired by either homology-dependent or homology-independent pathways. Using a novel intron-based genetic assay to identify rare homology-independent DNA rearrangements associated with repair of a chromosomal DSB in S. cerevisiae, we observed that approximately 20% of rearrangements involved endogenous DNA insertions at the break site. We have analyzed 37 inserts and find they fall into two distinct classes: Ty1 cDNA intermediates varying in length from 140 bp to 3.4 kb and short mitochondrial DNA fragments ranging in size from 33 bp to 219 bp. Several inserts consist of multiple noncontiguous mitochondrial DNA segments. These results demonstrate an ongoing mechanism for genome evolution through acquisition of organellar and mobile DNAs at DSB sites.
Yu
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Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854, USA.
Gabriel
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D001483:Base Sequence; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D019457:Chromosome Breakage / Q000235:genetics*; D015825:Chromosomes, Fungal / Q000187:drug effects / Q000235:genetics; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics*; D004271:DNA, Fungal / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects; D019143:Evolution, Molecular; D005690:Galactose / Q000494:pharmacology; D005800:Genes, Fungal / Q000235:genetics; D007438:Introns / Q000235:genetics; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D011995:Recombination, Genetic / Q000187:drug effects / Q000235:genetics; D018626:Retroelements / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid
D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D018626:Retroelements; D029701:Saccharomyces cerevisiae Proteins; C037725:SCEI protein, S cerevisiae; D015252:Deoxyribonucleases, Type II Site-Specific; D005690:Galactose