Enrichment of DNA replication intermediates by EdU pull down

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Analyzing replication fork structures via electron microscopy (EM) offers crucial mechanistic insights into DNA replication.
• A significant hurdle in EM analysis of DNA replication is the scarcity of replication intermediates.

Purpose of the Study:

• To develop a novel method for enriching replicating DNA and replication fork structures.
• To overcome the challenge of low abundance of replication intermediates in DNA replication studies.

Main Methods:

• Developed an EdU-pull-down procedure involving a brief pulse of EdU (5-ethynyl-2'-deoxyuridine).
• Utilized copper-catalyzed azide-alkyne cycloaddition (CuAAC) to attach a cleavable biotin moiety to EdU, minimizing DNA damage.
• Purified biotinylated DNA using streptavidin beads under conditions favoring long DNA filament association.
• Eluted purified DNA by cleaving the biotin moiety.

Main Results:

• The EdU-pull-down procedure achieved over 150-fold enrichment of replicating DNA.
• Demonstrated approximately 50-fold enrichment of replication fork structures, verified by EM.
• The method effectively enriches for crucial DNA replication intermediates.

Conclusions:

• The developed EdU-pull-down procedure significantly enhances the yield of replicating DNA and replication fork structures.
• This method is valuable for improving the analysis of replication intermediates in EM studies.
• The technique holds potential for advancing various methods studying replicating DNA.