Two novel dATP analogs for DNA photoaffinity labeling

Area of Science:

• Biochemistry
• Molecular Biology
• Nucleic Acid Chemistry

Background:

• Deoxyadenosine triphosphate (dATP) is a fundamental building block for DNA synthesis.
• Photoreactive analogs of nucleotides are valuable tools for studying DNA-protein interactions.
• Developing novel photoreactive dATP analogs can enhance our understanding of DNA polymerase mechanisms.

Purpose of the Study:

• To synthesize and characterize two novel photoreactive dATP analogs: N(6)-[4-azidobenzoyl-(2-aminoethyl)]-2'-deoxyadenosine-5'-triphosphate (AB-dATP) and N(6)-[4-[3-(trifluoromethyl)-diazirin-3-yl]benzoyl-(2-aminoethyl)]-2'-deoxyadenosine-5'-triphosphate (DB-dATP).
• To investigate the enzymatic incorporation of these analogs into DNA.
• To demonstrate the utility of these analogs in studying DNA polymerase-DNA interactions via photocrosslinking.

Main Methods:

• Multi-step chemical synthesis starting from 2'-deoxyadenosine-5'-monophosphate (dAMP).
• Enzymatic incorporation of synthesized analogs into DNA using the exonuclease-free Klenow fragment of DNA polymerase I in a primer extension reaction.
• UV irradiation of DNA polymerase I and DNA mixtures containing the photoreactive analogs to induce photocrosslinking.

Main Results:

• Successful synthesis of AB-dATP and DB-dATP with photoreactive moieties attached to the N(6) position of adenine.
• Efficient incorporation of N(6)-dATP and its photoreactive analogs into DNA by DNA polymerase I.
• Specific photocrosslinking of DNA polymerase I to DNA was observed upon UV irradiation of reactions containing AB-dATP or DB-dATP.

Conclusions:

• The synthesized photoreactive dATP analogs are suitable substrates for enzymatic DNA incorporation.
• These analogs enable the study of DNA polymerase I binding to DNA through photocrosslinking.
• The developed analogs provide a novel tool for investigating protein-DNA interactions in molecular biology.