Abstract
The GC-rich nuclease hypersensitivity element III1 (NHE III1) of the c-MYC promoter largely controls the transcriptional activity of the c-MYC oncogene. The C-rich strand in this region can form I-motif DNA secondary structures. We determined the folding pattern of the major I-motif formed in the NHE III1, which can be formed at near-neutral pH. While we find that the I-motif formed in the four 3′ consecutive runs of cytosines appears to be the most favored, our results demonstrate that the C-rich strand of the c-MYC NHE III1 exhibits a high degree of dynamic equilibration. Using a trisubstituted oligomer of this region, we determined the formation of two equilibrating loop isomers, one of which contains a flipped-out cytosine. Our results indicate that the intercalative cytosine+-cytosine base pairs are not always necessary for an intramolecular Imotif. The dynamic character of the c-MYC I-motif is intrinsic to the NHE III1 sequence and appears to provide stability to the c-MYC I-motif.
Original language | English (US) |
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Article number | e11647 |
Journal | PloS one |
Volume | 5 |
Issue number | 7 |
DOIs | |
State | Published - Jul 19 2010 |
ASJC Scopus subject areas
- General