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Four-Stranded Intercalated Cytosine-Rich Molecules: Novel Insights into DNA Structure and Stability |
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| Authors: | Imre Berger Martin Egli Nada Spackova Jiri Sponer Alexander Rich |
| Institution: | 1. Institute for Molecular Biology and Biophysics ETH , CH-8093, Zürich, Switzerland;2. Department of Molecular Pharmacology and Biological Chemistry , NWU Medical School , Chicago, IL, 60611, USA;3. Academy of Sciences of the Czech Republic , 61265, Brno;4. J. Heyrovsky Institute of Physical Chemistry , 18223, Prague, Czech Republic;5. Department of Biology , MIT , Cambridge, MA, 02139, USA |
| Abstract: | Abstract DNA fragments with stretches of cytosine residues can form four-stranded intercalated i-DNA molecules stabilized by hemiprotonated cytosine·cytosine+ (C·C+) base pairs. Intriguing features of this motif are the accomodation of base stacking that is unfavorable due to electrostatic repulsion and the close approach of phosphates in narrow grooves of the molecule. Unusual sources of stability in this structure involve sugar-base stacking and CH-O interribose short contacts between the backbones of adjacent strands. |
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