1JB7: Dna G-Quartets In A 1.86 A Resolution Structure Of An Oxytricha Nova Telomeric Protein-Dna Complex

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.
PDB ID: 1JB7Download
MMDB ID: 95139
PDB Deposition Date: 2001/6/2
Updated in MMDB: 2011/11
Experimental Method:
x-ray diffraction
Resolution: 1.86  Å
Source Organism:
Sterkiella nova
Similar Structures:
Biological Unit for 1JB7: pentameric; determined by author
Molecular Components in 1JB7
Label Count Molecule
Proteins (2 molecules)
Telomere-binding Protein Alpha Subunit
Molecule annotation
Telomere-binding Protein Beta Subunit
Molecule annotation
Nucleotide(1 molecule)
Molecule annotation
Chemicals (5 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB