| dc.description.abstract | The ends of linear chromosomes resemble half of a double-strand break and need to be protected and replicated to preserve the genome. Telomeres are evolutionarily conserved structures that cap the ends of chromosomes and are composed of a repetitive nucleotide sequence bound by a protein complex, Shelterin. Telomeres protect the ends of chromosomes and promote replication. However, telomeres also pose a potential obstacle to replication which must be overcome to preserve their length. We have begun to set up a system to study linear chromosomes in Xenopus egg extracts, but although telomeres are stable at low concentrations in extracts, they are not stable at high concentrations. We found that inhibition of Mre11 and DNA2 nucleases stabilized linear chromosomes in extracts regardless of the presence of telomeres. Our data suggest the extracts are missing important protective factors necessary to support high concentrations of telomeric DNA. Additionally, increasing the length of telomeres in extracts did not increase stability in extracts which may be due to a lack of the appropriate telomere structure. Overall, our data suggest that limiting levels of telomere capping and/or processing enzymes render them susceptible to exonucleases. | |
