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Molecular analysis of telomere fusions in Arabidopsis : multiple pathways for chromosome end‐joining
Author(s) -
Heacock Michelle,
Spangler Elizabeth,
Riha Karel,
Puizina Jasna,
Shippen Dorothy E
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600236
Subject(s) - telomere , ku70 , biology , arabidopsis , genetics , non homologous end joining , ku80 , telomere binding protein , telomerase , mutant , homologous recombination , microbiology and biotechnology , dna repair , dna , gene , dna binding protein , transcription factor
End‐to‐end fusion of critically shortened telomeres in higher eucaryotes is presumed to be mediated by nonhomologous end‐joining (NHEJ). Here we describe two PCR‐based methods to monitor telomere length and examine the fate of dysfunctional telomeres in Arabidopsis lacking the catalytic subunit of telomerase (TERT) and the DNA repair proteins Ku70 and Mre11. Primer extension telomere repeat amplification relies on the presence of an intact G‐overhang, and thus measures functional telomere length. The minimum functional telomere length detected was 300–400 bp. PCR amplification and sequence analysis of chromosome fusion junctions revealed exonucleolytic digestion of dysfunctional ends prior to fusion. In ku70 tert mutants, there was a greater incidence of microhomology at the fusion junction than in tert mutants. In triple ku70 tert mre11 mutants, chromosome fusions were still detected, but microhomology at the junction was no longer favored. These data indicate that both Ku70 and Mre11 contribute to fusion of critically shortened telomeres in higher eucaryotes. Furthermore, Arabidopsis processes critically shortened telomeres as double‐strand breaks, using a variety of end‐joining pathways.