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Nuclease P1-mediated fluorescence postlabeling assay of AAF modified DNA model d(TACGTA) and calf-thymus DNA
Abstract:
Fluorescence postlabeling assay for DNA damage combines enzymatic digestion of modified DNA to nucleoside monophosphates and fluorescence postlabeling. However, to facilitate the quantitative release of bulky adducts that are not readily obtained as mononucleotides, a different mechanism is essential. In order to test the application potential of nuclease P1-mediated fluorescence postlabeling to assay bulky adduct, d(TACGTA) was reacted with N-acetoxy-2-acetylamino-fluorene. The major product, characterized by nmr as AAF adduct of the guanine moiety at the C-8 position, was used as a DNA model. Nuclease P1 digestion of the modified oligomer excised the adduct in two forms (3:1) which were identified as AAF modified d(pGpT) and dpG respectively by cochromotography with authentic markers. Fluorescence postlabeling assay of AAF modified d(TACGTA) detected both forms of the excised adduct. The application of the overall procedure to assay AAF modified calf-thymus DNA demonstrated that the extension of fluorescence postlabeling technique from the mononucleotide to the dinucleotide version expands the scope of the assay.
Insights
This study introduces a nuclease P1-enhanced fluorescence postlabeling assay for detecting bulky DNA adducts. The method successfully quantifies adducts released as dinucleotides, expanding assay capabilities.
Area of Science:
- Biochemistry
- Molecular Biology
- Analytical Chemistry
Background:
- Fluorescence postlabeling assays are crucial for detecting DNA damage.
- Current methods struggle with quantitative release of bulky DNA adducts.
- A novel mechanism is needed to improve the detection of complex DNA modifications.
Purpose of the Study:
- To evaluate nuclease P1-mediated fluorescence postlabeling for bulky adduct detection.
- To adapt existing assays for dinucleotide adducts.
- To enhance the scope of DNA damage assessment techniques.
Main Methods:
- Utilized a DNA model, d(TACGTA), reacted with N-acetoxy-2-acetylamino-fluorene (AAF).
- Employed nuclease P1 digestion to excise AAF adducts.
- Performed fluorescence postlabeling on excised mononucleotide and dinucleotide adducts.
Main Results:
- Nuclease P1 digestion released AAF adducts in two forms: AAF-modified d(pGpT) and dpG.
- Fluorescence postlabeling successfully detected both excised adduct forms.
- The assay was applied to AAF-modified calf-thymus DNA, demonstrating its effectiveness.
Conclusions:
- Nuclease P1-mediated fluorescence postlabeling is effective for assaying bulky DNA adducts.
- Extending the assay to dinucleotides significantly broadens its applicability.
- This technique enhances the ability to detect and quantify DNA damage.