double-stranded DNA 3'-5' DNA exonuclease activity

Definition

Target type: molecularfunction

Catalysis of the sequential cleavage of mononucleotides from a free 3' terminus of a double-stranded DNA molecule. [GOC:mah, PMID:22562358]

Double-stranded DNA 3'-5' exonuclease activity refers to the enzymatic ability to degrade double-stranded DNA by removing nucleotides from the 3' end of the molecule. This activity is crucial for a variety of cellular processes, including DNA replication, repair, and recombination.

Here is a detailed description of the molecular function of this activity:

* **Mechanism:** The exonuclease enzyme binds to the double-stranded DNA molecule and uses its active site to hydrolyze the phosphodiester bond between the 3'-hydroxyl group of the terminal nucleotide and the phosphate group of the penultimate nucleotide. This results in the release of a single nucleotide from the 3' end of the DNA molecule. The enzyme then moves one nucleotide position towards the 5' end and repeats the process, progressively degrading the DNA strand.

* **Specificity:** The exonuclease typically exhibits a strong preference for double-stranded DNA substrates. Some exonucleases can also exhibit limited activity on single-stranded DNA, but their primary function is on double-stranded DNA.

* **Directionality:** The exonuclease activity is 3'-5', meaning it proceeds from the 3' end towards the 5' end of the DNA molecule.

* **Biological Significance:**
* **DNA Replication:** During DNA replication, exonucleases are essential for removing incorrect nucleotides that may be incorporated by DNA polymerase. This proofreading function ensures the fidelity of DNA replication.
* **DNA Repair:** Exonucleases play a critical role in DNA repair pathways. They can remove damaged nucleotides from the DNA strand to facilitate repair by other enzymes.
* **DNA Recombination:** Exonucleases contribute to homologous recombination by processing the ends of DNA molecules to generate single-stranded DNA tails that are necessary for recombination.
* **Regulation:** The activity of exonucleases is tightly regulated to ensure that they only act on specific DNA substrates at appropriate times. This regulation involves interactions with other proteins and modifications of the exonuclease itself.

Overall, the 3'-5' exonuclease activity is a fundamental enzymatic function that is vital for maintaining the integrity and stability of the genome.'
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Proteins (2)

Compounds (18)