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Crystal structure of a DNA Holliday junction
M Ortiz-Lombardía1, A González, R Eritja
1Institut de Biologia Molecular de Barcelona, C.S.I.C., Jordi Girona 18, E-08034 Barcelona, Spain.
Nature Structural Biology
|October 3, 1999
Summary
We determined the crystal structure of a Holliday junction, a key intermediate in DNA recombination. This reveals how its compact structure influences DNA repair and genetic diversity.
Area of Science:
- Molecular Biology
- Structural Biology
- Genetics
Background:
- DNA recombination is vital for genetic diversity and genome stability.
- Holliday junctions are central intermediates in DNA recombination.
- Recombination enzymes act on Holliday junctions to facilitate branch migration and resolution.
Purpose of the Study:
- To determine the crystal structure of a four-way DNA junction.
- To elucidate the structural basis for Holliday junction function in recombination.
Main Methods:
- Crystal structure determination using multiwavelength anomalous diffraction.
- Refinement of the structure to 2.16 Å resolution.
Main Results:
- The structure exhibits two-fold symmetry with pairwise stacking of double-helical arms.
- Two continuous antiparallel B-DNA helices cross in a right-handed manner, containing G-A mismatches.
- Specific hydrogen bonds and van der Waals contacts at the branch point dictate junction conformation and stability.
Conclusions:
- The determined structure provides insights into Holliday junction conformation.
- Structural features explain the preference for specific stacked conformers.
- Understanding junction structure is crucial for comprehending DNA recombination mechanisms.