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- Title
t-loops at trypanosome telomeres.
- Authors
Muñoz-Jordán, Jorge L.; Cross, George A. M.; de Lange, Titia; Griffith, Jack D.
- Abstract
Mammalian telomeres form large duplex loops (t-loops) that may sequester chromosome ends by invasion of the 3' TTAGGG overhang into the duplex TTAGGG repeat array. Here we document t-loops in Trypanosoma brucei, a kinetoplastid protozoan with abundant telomeres due to the presence of many mini-chromosomes. These telomeres contained 10-20 kb duplex TTAGGG repeats and a 3' TTAGGG overhang. Electron microscopy of psoralen/UV cross-linked DNA revealed t-loops in enriched telomeric restriction fragments and at the ends of isolated minichromosomes. In mammals, t-loops are large (up to 25 kb), often comprising most of the telomere. Despite similar telomere lengths, trypanosome t-loops were much smaller (∼1 kb), indicating that t-loop sizes are regulated. Coating of non-cross-linked minichromosomes with Escherichia coli single-strand binding protein (SSB) often revealed 3' overhangs at both telomeres and several cross-linked minichromosomes had t-loops at both ends. These results suggest that t-loops and their prerequisite 3' tails can be formed on the products of both leading and lagging strand synthesis. We conclude that t-loops are a conserved feature of eukaryotic telomeres.
- Subjects
TELOMERES; ESCHERICHIA coli; CHROMOSOMES; EUKARYOTIC cells; CARRIER proteins; DNA
- Publication
EMBO Journal, 2001, Vol 20, Issue 3, p579
- ISSN
0261-4189
- Publication type
Article
- DOI
10.1093/emboj/20.3.579