Stable inheritance of telomere chromatin structure and function in the absence of telomeric repeats.
It is generally believed that telomeric repeats are a necessary and sufficient cis-element for telomere function. Here we show that telomere structure and meiotic function are stably inherited in fission yeast circular chromosomes that have lost all telomeric repeats. We found that the telomeric repeat binding protein, Taz1, and the heterochromatin protein, Swi6, remain associated with subtelomeres in the absence of telomeric repeats. We also found that the fusion point of circular chromosomes that lack telomeric repeats associates with SPB (the yeast counterpart of the centrosome) in the premeiotic horsetail stage, similarly to wild-type telomeres. However, a taz1+ deletion/reintroduction experiment revealed that the maintenance of Taz1 binding and premeiotic function is achieved via different strategies. Taz1 is recruited to subtelomeres by an autonomous element present in subtelomeric DNA, thus in a genetic mechanism. In contrast, the premeiotic subtelomere-SPB association is maintained in an epigenetic manner. These results shed light on the previously unrecognized role played by the subtelomere and underscore the robust nature of the functional telomere complex that is maintained by both genetic and epigenetic mechanisms. Furthermore, we suggest that the establishment and the maintenance of the functional telomere complex are mechanistically distinguishable.
Sadaie
Mahito
M
Laboratory of Molecular and Cellular Assembly, Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
Naito
Taku
T
Ishikawa
Fuyuki
F
D002843:Chromatin / Q000235:genetics*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004268:DNA-Binding Proteins; D012091:Repetitive Sequences, Nucleic Acid; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism; D019098:Telomerase / Q000235:genetics / Q000378:metabolism; D016615:Telomere / Q000235:genetics*; D034501:Telomere-Binding Proteins / Q000378:metabolism
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029702:Schizosaccharomyces pombe Proteins; C465958:Swi6 protein, S pombe; D034501:Telomere-Binding Proteins; C104344:taz1 protein, S pombe; C509188:trt1 protein, S pombe; D019098:Telomerase