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Long-Range Hairpin Slippage Reconfiguration Dynamics in Trinucleotide Repeat Sequences
Cheng-Wei Ni1, Yu-Jie Wei1, Yang-I Shen1
1Department of Chemistry , National Taiwan Normal University , Taipei 11677 , Taiwan.
The Journal of Physical Chemistry Letters
|June 27, 2019
Summary
Trinucleotide repeat sequences form stable hairpins implicated in genetic diseases. We discovered a dynamic two-state configuration interchange in CTG repeats, proposing a bulge translocation model that may explain error accumulation in repeat expansion.
Area of Science:
- Genetics
- Molecular Biology
- Biophysics
Background:
- Trinucleotide repeat (TNR) sequences are associated with neurodegenerative genetic disorders.
- TNRs form hairpin structures that impede DNA replication and repair, causing dynamic mutations.
- The configurational rearrangements of these hairpins are critical for ongoing repeat expansion.
Purpose of the Study:
- To investigate the structural dynamics of trinucleotide repeat sequences at the single-molecule level.
- To elucidate the mechanism underlying configurational rearrangements in CTG repeats.
- To understand the role of these dynamics in genetic mutation and disease.
Main Methods:
- Utilized single-molecule biophysics techniques to study CTG repeat sequences.
- Performed repeat-number-dependent kinetic analysis.
- Developed a bulge translocation model based on experimental observations.
Main Results:
- Discovered a unique dynamic two-state configuration interchange in odd-numbered CTG repeat sequences.
- Demonstrated that this interchange is driven by local instability.
- Proposed a bulge translocation model applicable to longer, disease-relevant hairpins.
Conclusions:
- The dynamic configurational interchange of CTG repeats plays a crucial role in their structural dynamics.
- The proposed bulge translocation model offers a potential mechanism for error accumulation in trinucleotide repeat expansion.
- These findings have implications for understanding the pathogenesis of genetic diseases caused by TNRs.
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