Polymorphic crystal structures of an all-AT DNA dodecamer

Area of Science:

• Structural Biology
• Biochemistry
• Crystallography

Background:

• DNA crystallization is crucial for understanding its structure-function relationships.
• The influence of environmental factors like solvents and ions on DNA crystal formation is not fully understood.
• All-AT DNA sequences exhibit unique properties that may lead to novel crystallization behaviors.

Purpose of the Study:

• To investigate the impact of various solvents and ions on the crystallization of an all-AT dodecamer.
• To characterize the resulting DNA crystal structures and their spatial organization.
• To explore the versatility of DNA crystal formation and its dependence on crystallization conditions.

Main Methods:

• Crystallization of the all-AT dodecamer d(AATAAATTTATT)2 under varying solvent and ionic conditions.
• X-ray diffraction analysis to determine the crystal structures and identify different crystal forms.
• Comparative analysis of DNA-DNA interactions in different crystal forms.

Main Results:

• Seven distinct crystal forms of the all-AT dodecamer were obtained, all adopting the B-DNA form.
• The spatial organization of stacked duplex columns varied, forming either parallel or crossed arrangements.
• Specific ions like Mg(2+) and Ni(2+) promoted compact crossed structures, altering DNA-DNA interactions compared to mixed sequences.
• Observed liquid crystals with unusual macroscopic shapes.

Conclusions:

• Solvent and ionic environments significantly modulate DNA-DNA interactions and crystal packing.
• The all-AT sequence demonstrates exceptional versatility in forming diverse crystal structures.
• Findings highlight the potential for DNA crystal engineering and suggest implications for DNA's biological activity.