Human telomeric C-strand tetraplexes.

S Ahmed; A Kintanar; E Henderson

doi:10.1038/nsb0294-83

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PubMed · 7656022

Human telomeric C-strand tetraplexes.

S Ahmed·A Kintanar·E Henderson

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Abstract

Telomeric C-strand sequences form non-Watson-Crick base-paired structures in supercoiled plasmids and in oligonucleotides at low pH. Here we examine oligonucleotides composed of 2 or 4 repeats of the human telomeric C-strand sequence d(CCCTAA)n. At low pH, the 2-repeat molecule forms a dimer which exhibits H1'-H1' nuclear Overhauser effects (NOEs) between stacked CC+ base pairs. These NOEs are characteristic of the i-motif, which is a tetraplex composed of two intercalated CC+ duplexes. The 4-repeat molecule forms an intramolecular monomeric structure at low pH, suggesting that four contiguous cytosine tracts fold into a CC+ intercalated tetraplex. These unusual structures may be relevant to the formation of guanine tetraplexes by complementary G-rich sequences. They may also provide a general mechanism for self-recognition by nucleic acids.

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Base Sequence DNA Humans Hydrogen-Ion Concentration Magnetic Resonance Spectroscopy Models, Molecular Molecular Sequence Data Molecular Structure Nucleic Acid Conformation Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S.

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S Ahmed, A Kintanar, E Henderson. 1994. Human telomeric C-strand tetraplexes.. https://doi.org/10.1038/nsb0294-83

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