106d
From Proteopedia
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SOLUTION STRUCTURES OF THE I-MOTIF TETRAMERS OF D(TCC), D(5MCCT) AND D(T5MCC). NOVEL NOE CONNECTIONS BETWEEN AMINO PROTONS AND SUGAR PROTONS
Overview
BACKGROUND: At slightly acid or even neutral pH, oligodeoxynucleotides, that include a stretch of cytidines form a tetramer structure in which two, parallel-stranded duplexes have their hemi-protonated C.C+ base pairs, face-to-face and fully intercalated, in a so-called i-motif, first, observed serendipitously in [d(TC5)]4. RESULTS: A high-definition, structure of [d(TCC)]4 was computed on the basis of inter-residue, distances corresponding to 21 NOESY cross-peaks measured at short mixing, times. A similarly defined structure of [d(5mCCT)]4 was also obtained. A, small number of very characteristic (amino proton)-(sugar proton), cross-peaks entails the intercalation topology. The structure is generally, similar to that of [d(TC5)]4. The sequence d(T5mCC) forms two tetramers in, comparable proportions. The intercalation topologies are read off the two, patterns of (amino proton)-(sugar proton) cross-peaks: one is the same as, in the d(TCC) tetramer, the other has the intercalated strands shifted by, one base, which avoids the steric hindrance between the methyl groups of, the 5mC pairs of the two duplexes. CONCLUSIONS: The structures obtained in, this work and the procedures introduced to characterize them and to solve, the problems linked to the symmetry of the structure provide tools for, further exploring the conditions required for formation of the i-motif.
About this Structure
106D is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Solution structures of the i-motif tetramers of d(TCC), d(5methylCCT) and d(T5methylCC): novel NOE connections between amino protons and sugar protons., Leroy JL, Gueron M, Structure. 1995 Jan 15;3(1):101-20. PMID:7743125
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