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Analyzing and Building Nucleic Acid Structures with 3DNA
Published on: April 26, 2013
Helical chirality: a link between local interactions and global topology in DNA
1Information Génomique et Structurale, CNRS-UPR2589, Institut de Microbiologie de la Méditerranée, Parc Scientifique de Luminy, Marseille, France. Youri.Timsit@igs.cnrs-mrs.fr
Plos One
|February 23, 2010
Summary
DNA supercoiling influences cellular functions through DNA-DNA interactions. Crossovers differ in geometry and stability, with right-handed crossovers indicating unusual DNA topology and potentially altering DNA dynamics.
Area of Science:
- Structural Biology
- Biophysics
- Molecular Biology
Background:
- DNA supercoiling is crucial for cellular processes.
- Local DNA-DNA interactions, particularly crossovers, affect DNA properties and functions.
- The influence of DNA crossover structure and stability on DNA topology remains unclear.
Purpose of the Study:
- To investigate how DNA crossover geometry and stability relate to DNA topology.
- To elucidate the role of DNA's intrinsic helical chirality in DNA-DNA interactions.
- To understand the implications of these interactions for DNA physical properties and evolution.
Main Methods:
- Crystallographic analysis of DNA crossovers.
- Assessment of DNA-DNA interactions (groove-backbone, groove-groove).
- Evaluation of stabilization in solution with divalent cations (previous work).
Main Results:
- Oppositely handed DNA crossovers exhibit distinct geometries due to DNA's helical chirality.
- Right-handed crossovers involve sequence-specific groove-backbone interactions and Mg(2+) sites.
- Left-handed crossovers are mediated by groove-groove interactions.
- Left-handed crossovers are unstable and found in negatively supercoiled DNA.
- Stable right-handed crossovers signify unusual topological states (positively supercoiled or relaxed DNA).
Conclusions:
- DNA topology can be locally sensed through distinct inter-segmental interactions.
- Supercoiled DNA molecules with opposite topological signs exhibit different physical properties.
- Stable right-handed crossovers in relaxed or positively supercoiled DNA likely slow DNA dynamics.
- DNA's helical chirality may have influenced the evolution of DNA topology.
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