Covalently linked tandem lesions in DNA

Area of Science:

• Molecular Biology
• Biochemistry
• Radiation Chemistry

Background:

• Reactive oxygen species (ROS) are a major source of DNA damage.
• Tandem lesions, where two adjacent nucleotides are modified, represent a complex form of DNA damage.
• Covalently linked tandem lesions possess unique mass spectrometry signatures.

Purpose of the Study:

• To comprehensively identify and quantify covalently linked tandem lesions in X-irradiated DNA.
• To investigate the influence of oxygen on the formation of these lesions.

Main Methods:

• DNA irradiation using X-rays under both deoxygenated and oxygenated aqueous conditions.
• Analysis of DNA damage using liquid chromatography-tandem mass spectrometry (LC-MS/MS).
• Characterization of unique elution profiles specific to covalently linked tandem lesions.

Main Results:

• A total of 15 distinct covalently linked tandem lesions were detected in DNA irradiated under deoxygenated conditions.
• Five covalently linked tandem lesions were identified in DNA irradiated under oxygenated conditions.
• LC-MS/MS successfully differentiated and detected these specific DNA lesions based on their elution profiles.

Conclusions:

• X-irradiation induces various covalently linked tandem DNA lesions.
• The presence of oxygen significantly reduces the yield of these specific DNA lesions.
• LC-MS/MS is a powerful tool for the comprehensive detection of complex DNA damage like tandem lesions.