Aprataxin is a DNA-binding protein involved in different types of DNA break repair. The enzyme acts (among other activities) on abortive DNA ligation intermediates that contain an adenylate covalently linked to the 5'-phosphate DNA terminus. It also acts when the adenylate is covalently linked to the 5'-phosphate of a ribonucleotide linked to a DNA strand, which is the result of abortive ligase activty on products of EC 3.1.26.4, ribonuclease H, an enzyme that cleaves RNA-DNA hybrids on the 5' side of the ribonucleotide found in the 5'-RNA-DNA-3' junction. Aprataxin binds the adenylate group to a histidine residue within the active site, followed by its hydrolysis from the nucleic acid and eventual release, leaving a 5'-phosphate terminus that can be efficiently rejoined. The enzyme also possesses the activities of EC 3.6.1.70, guanosine-5'-diphospho-5'-[DNA] diphosphatase, and EC 3.6.1.72, DNA-3'-diphospho-5'-guanosine diphosphatase.
History
EC 3.6.1.71 created 2017 as EC 3.1.11.7, transferred 2019 to EC 3.6.1.71
