title: Telomere loops and homologous recombination-dependent telomeric circles in a Kluyveromyces lactis telomere mutant strain.
abstract: The Kluyveromyces lactis ter1-16T strain contains mutant telomeres that are poorly bound by Rap1, resulting in a telomere-uncapping phenotype and significant elongation of the telomeric DNA. The elongated telomeres of ter1-16T allowed the isolation and examination of native yeast telomeric DNA by electron microscopy. In the telomeric DNA isolated from ter1-16T, looped molecules were observed with the physical characteristics of telomere loops (t-loops) previously described in mammalian and plant cells. ter1-16T cells were also found to contain free circular telomeric DNA molecules (t-circles) ranging up to the size of an entire telomere. When the ter1-16T uncapping phenotype was repressed by overexpression of RAP1 or recombination was inhibited by deletion of rad52, the isolated telomeric DNA contained significantly fewer t-loops and t-circles. These results suggest that disruption of Rap1 results in elevated recombination at telomeres, leading to increased strand invasion of the 3' overhang within t-loop junctions and resolution of the t-loop junctions into free t-circles.
authors.affiliation: Corresonding author. Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Cesare
authors.forename: Cindy
authors.initials: C
authors.lastname: Groff-Vindman
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Compton
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McEachern
authors.forename: Jack D
authors.initials: JD
authors.lastname: Griffith
mesh_terms: D001483:Base Sequence; D002850:Chromatography, Gel; D004271:DNA, Fungal / Q000235:genetics; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D007716:Kluyveromyces / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure*; D008854:Microscopy, Electron; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D051721:Rad52 DNA Repair and Recombination Protein / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics*; D035182:TATA Box Binding Protein-Like Proteins / Q000235:genetics / Q000378:metabolism; D016615:Telomere / Q000235:genetics* / Q000648:ultrastructure*
chemical_list: D004271:DNA, Fungal; D051721:Rad52 DNA Repair and Recombination Protein; D035182:TATA Box Binding Protein-Like Proteins