single-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 single-stranded DNA molecule. [GOC:mah, PMID:22562358]

Single-stranded DNA 3'-5' exonuclease activity is a catalytic process that involves the removal of nucleotides from the 3' end of a single-stranded DNA molecule. This activity is essential for a variety of cellular processes, including DNA replication, repair, and recombination. During DNA replication, exonucleases can remove mismatched nucleotides that are incorporated into the newly synthesized DNA strand. This ensures that the replicated DNA is faithful to the original template. In DNA repair, exonucleases can remove damaged nucleotides from the DNA strand, allowing for the synthesis of a new, undamaged strand. Finally, in DNA recombination, exonucleases can remove nucleotides from the ends of broken DNA molecules, allowing for the rejoining of the broken strands. The mechanism of single-stranded DNA 3'-5' exonuclease activity involves the binding of the exonuclease to the DNA substrate. The exonuclease then cleaves the phosphodiester bond between the 3' hydroxyl group of the penultimate nucleotide and the 5' phosphate group of the terminal nucleotide. This process releases the terminal nucleotide and generates a new 3' hydroxyl group that can serve as a substrate for further exonucleolytic cleavage. The specificity of single-stranded DNA 3'-5' exonucleases for single-stranded DNA is due to the presence of a binding site that recognizes and interacts with the single-stranded DNA backbone. This binding site typically consists of positively charged amino acid residues that interact with the negatively charged phosphate groups of the DNA backbone. The exonucleases also exhibit a preference for the 3' end of the DNA molecule, which is dictated by the orientation of the catalytic site. The catalytic site is typically located near the 3' end of the DNA molecule, allowing for the efficient cleavage of the phosphodiester bond between the 3' hydroxyl group and the 5' phosphate group. Single-stranded DNA 3'-5' exonuclease activity is a critical component of DNA metabolism. The activity of these enzymes is tightly regulated to ensure that the appropriate amount of exonucleolytic activity occurs in the cell. In addition to their role in DNA replication, repair, and recombination, single-stranded DNA 3'-5' exonucleases are also involved in other cellular processes, such as the regulation of gene expression and the degradation of viral DNA.'
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Proteins (2)

Compounds (8)