1jb7
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DNA G-Quartets in a 1.86 A Resolution Structure of an Oxytricha nova Telomeric Protein-DNA Complex
OverviewOverview
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.
About this StructureAbout this Structure
1JB7 is a Protein complex structure of sequences from Sterkiella nova with and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
DNA G-quartets in a 1.86 A resolution structure of an Oxytricha nova telomeric protein-DNA complex., Horvath MP, Schultz SC, J Mol Biol. 2001 Jul 6;310(2):367-77. PMID:11428895
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