Because there is no complete DNA polymerase structure, tau protein exhibits nuclease activity and binds to DNA in the palm, finger, and clamp structures. To add to what has already been said, the tau protein's DNA mitochondrial polymerase exonuclease and DNA polymerase III delta subunit C-termina domain activities suggest that it can also bind and work with circular DNA in mitochondria. (2) DNA methylase and ATP-dependent nucleasesdomains ATP-dependent DNA ligase family profile (PS50160) is a DNA ligase (polydeoxyribonucleotide synthase), an enzyme that helps connect two pieces of DNA by making a nucleotide ester bond between phosphate and deoxyribose. It is involved in DNA replication, DNA repair, and DNA recombination. There are DNA ligases that are ATP-dependent in eukaryotic, archaeal, viral, and bacteriophage cells.The conserved lysine residue serves as the adenylation site.