DNA G-quartets in a 1.86 A resolution structure of an Oxytricha nova telomeric protein-DNA complex.Horvath, M.P., Schultz, S.C.
(2001) J.Mol.Biol. 310: 367-377
- PubMed: 11428895
- DOI: 10.1006/jmbi.2001.4766
- PubMed Abstract:
- Crystal Structure of the Oxytricha Nova Telomere End Binding Protein Complexed with Single Strand DNA
Horvath, M.P.,Schweiker, V.L.,Bevilacqua, J.M.,Ruggles, J.A.,Schultz, S.C.
(1998) Cell 95: 963
- Refined Solution Structure of the Dimeric Quadruplex Formed from the Oxytricha Telomeric Oligonucleotide d(GGGGTTTTGGGG)
Schultze, P.,Smith, F.W.,Feigon, J.
(1994) Structure 2: 221
The Oxytricha nova telomere end binding protein (OnTEBP) recognizes, binds and protects the single-stranded 3'-terminal DNA extension found at the ends of macronuclear chromosomes. The structure of this complex shows that the single strand GGGGTTTTGG ...
The Oxytricha nova telomere end binding protein (OnTEBP) recognizes, binds and protects the single-stranded 3'-terminal DNA extension found at the ends of macronuclear chromosomes. The structure of this complex shows that the single strand GGGGTTTTGGGG DNA binds in a deep cleft between the two protein subunits of OnTEBP, adopting a non-helical and irregular conformation. In extending the resolution limit of this structure to 1.86 A, we were surprised to find a G-quartet linked dimer of the GGGGTTTTGGGG DNA also packing within the crystal lattice and interacting with the telomere end binding protein. The G-quartet DNA exhibits the same structure and topology as previously observed in solution by NMR with diagonally crossing d(TTTT) loops at either end of the four-stranded helix. Additionally, the crystal structure reveals clearly visible Na(+), and specific patterns of bound water molecules in the four non-equivalent grooves. Although the G-quartet:protein contact surfaces are modest and might simply represent crystal packing interactions, it is interesting to speculate that the two types of telomeric DNA-protein interactions observed here might both be important in telomere biology.
Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA. Horvath@biology.utah.edu