CLUSTERING OF TELOMERES IN Saccharomyces cerevisiae
Straatman K.R., Sheehy M.M., Koziol M., Cotton V.E. and Louis E.J.
Department of Genetics, University of Leicester, UK The ends of the chromosomes, the telomeres, are important for capping the ends of the DNA molecule to prevent the chromosomes from fusing together. Several groups have shown by fluorescent in situ hybridization (FISH) or by labelling of telomere associated proteins that the telomeres of the yeast Saccharomyces cerevisiae are organized in several clusters at the nuclear periphery. We are interested in how this organization of telomeres is maintained and which telomeres are together in a cluster. We are also interested in whether telomeres stay together in a cluster or move between clusters. Live imaging has shown that telomeres are very dynamic structures and move several hundreds of nanometres per second. Mitotic recombination data suggests which telomeres might be clustered together. At the sequence level, several telomeres share homologous sequences in their subtelomeric regions, suggesting that they might be in the same cluster, at least part of the time during the cell cycle. These sequence alignments are in agreement with the genetic data. We are now trying to visualize this localization of the telomeres using FISH. To investigate if the sequence of a telomere determines in which cluster it is, a telomeric translocation between telomere XL and XVR was made and we are in the process of analysing these mutants genetically and physically.
