3exonucleases

3exonucleases are a class of enzymes that degrade nucleic acids from the 3' end. This process involves the sequential removal of nucleotides from the terminal 3' hydroxyl group of a DNA or RNA strand. These enzymes are crucial for various cellular processes, including DNA repair, replication, and RNA turnover. Their activity can be either processive, meaning they remain bound to the substrate and catalyze multiple cleavages, or distributive, where they detach after each cleavage. 3exonucleases play a vital role in maintaining genome stability and regulating gene expression by processing nucleic acid substrates. Examples of 3exonucleases include components of DNA repair pathways, such as Exo1 in eukaryotes and the exonuclease subunit of DNA polymerase I in prokaryotes. In RNA metabolism, specific 3exonucleases are involved in the degradation of messenger RNA and other RNA species. The precise function and substrate specificity of 3exonucleases can vary widely, reflecting their diverse roles in molecular biology.