Two roles for Rad50 in telomere maintenance.
We describe two roles for the Rad50 protein in telomere maintenance and the protection of chromosome ends. Using fluorescence in situ hybridisation (FISH) and fibre-FISH analyses, we show that absence of AtRad50 protein leads to rapid shortening of a subpopulation of chromosome ends and subsequently chromosome-end fusions lacking telomeric repeats. In the absence of telomerase, mutation of atrad50 has a synergistic effect on the number of chromosome end fusions. Surprisingly, this 'deprotection' of the shortened telomeres does not result in increased exonucleolytic degradation, but in a higher proportion of anaphase bridges containing telomeric repeats in atrad50/tert plants, compared to tert mutant plants. Absence of AtRad50 thus facilitates the action of recombination on these shortened telomeres. We propose that this protective role of Rad50 protein on shortened telomeres results from its action in constraining recombination to sister chromatids and thus avoiding end-to-end interactions.
Vannier
Jean-Baptiste
JB
UMR 6547 CNRS/Université Blaise Pascal, Aubière cedex, France.
Depeiges
Annie
A
White
Charles
C
Gallego
Maria Eugenia
ME
D000705:Anaphase / Q000502:physiology; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D020029:Base Pairing / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism; D032461:Chromosomes, Plant / Q000378:metabolism; D018744:DNA, Plant / Q000378:metabolism; D035264:Flowers / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D007211:Indoles; D008957:Models, Genetic; D009154:Mutation / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D015203:Reproducibility of Results; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000378:metabolism*
D029681:Arabidopsis Proteins; D018744:DNA, Plant; D007211:Indoles; C427727:rad50 protein, Arabidopsis; C007293:DAPI; D019098:Telomerase