294D

INTERCALATED CYTOSINE MOTIF AND NOVEL ADENINE CLUSTERS IN THE CRYSTAL STRUCTURE OF TETRAHYMENA TELOMERE

Summary for 294D

• Entry DOI: 10.2210/pdb294d/pdb
• Descriptor: DNA (5'-D(*AP*AP*CP*CP*CP*C)-3') (2 entities in total)
• Functional Keywords: unusual dna, quadruple helix, parallel-stranded tetraplex, base intercalated, flipped-out bases, adenine-cluster, continuous base stacking, dna
• Total number of polymer chains: 8
• Total formula weight: 13905.46

Authors

Cai, L.,Chen, L.,Raghavan, S.,Ratliff, R.,Moyzis, R.,Rich, A. (deposition date: 1996-10-30, release date: 1998-10-19, Last modification date: 2024-02-14)

Primary citation

Cai, L.,Chen, L.,Raghavan, S.,Ratliff, R.,Moyzis, R.,Rich, A.
Intercalated cytosine motif and novel adenine clusters in the crystal structure of the Tetrahymena telomere.
Nucleic Acids Res., 26:4696-4705, 1998

PubMed Abstract: The cytosine-rich strand of the Tetrahymena telomere consists of multiple repeats of sequence d(AACCCC). We have solved the crystal structure of the crystalline repeat sequence at 2.5 A resolution. The adenines form two different and previously unknown clusters (A clusters) in orthogonal directions with their counterparts from other strands, each containing a total of eight adenines. The clusters appear to be stable aggregates held together by base stacking and three different base-pairing modes. Two different types of cytosine tetraplexes are found in the crystal. Each four-stranded complex is composed of two intercalated parallel-stranded duplexes pointing in opposite directions, with hemiprotonated cytosine-cytosine (C.C+) base pairs. The outermost C.C+base pairs are from the 5'-end of each strand in one cytosine tetraplex and from the 3'-end of each strand in the other. The A clusters and the cytosine tetraplexes form two alternating stacking patterns, creating continuous base stacking in two perpendicular directions along the x - and z -axes. The adenine clusters could be organizational motifs for macromolecular RNA.

PubMed: 9753739
DOI: 10.1093/nar/26.20.4696

Experimental method

X-RAY DIFFRACTION (2.5 Å)