Interactions of TRF2 with model telomeric ends.
Telomeres are DNA-protein complexes at the ends of eukaryotic chromosomes, the integrity of which is essential for chromosome stability. An important telomere binding protein, TTAGGG repeat factor 2 (TRF2), is thought to protect telomere ends by remodeling them into T-loops. We show that TRF2 specifically interacts with telomeric ss/ds DNA junctions and binding is sensitive to the sequence of the 3', guanine-strand (G-strand) overhang and double-stranded DNA sequence at the junction. Association of TRF2 with DNA junctions hinders cleavage by exonuclease T. TRF2 interactions with the G-strand overhang do not involve the TRF2 DNA binding domain or the linker region. However, mobility shifts and atomic force microscopy show that the previously uncharacterized linker region is involved in DNA-specific, TRF2 oligomerization. We suggest that T-loop formation at telomere ends involves TRF2 binding to the G-strand overhang and oligomerization through both the known TRFH domain and the linker region.
Khan
Sheik J
SJ
Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, P.O. Box 016129 (R629), Miami, FL 33101-6129, USA.
Yanez
Giscard
G
Seldeen
Kenneth
K
Wang
Hongda
H
Lindsay
Stuart M
SM
Fletcher
Terace M
TM
D001483:Base Sequence; D001665:Binding Sites; D008969:Molecular Sequence Data; D011485:Protein Binding; D025941:Protein Interaction Mapping; D016615:Telomere / Q000737:chemistry*; D035341:Telomeric Repeat Binding Protein 2 / Q000737:chemistry*
D035341:Telomeric Repeat Binding Protein 2