| Comments |
The enzymes from the archaea?Thermococcus fumicolans?and?Thermococcus onnurineus?show high activity with either ATP or NAD+, and significantly lower activity with TTP, GTP, and CTP. The enzyme catalyses the ligation of DNA strands with 3′-hydroxyl and 5′-phosphate termini, forming a phosphodiester and sealing certain types of single-strand breaks in duplex DNA. Catalysis occurs by a three-step mechanism, starting with the activation of the enzyme by ATP or NAD+, forming a phosphoramide bond between adenylate and a lysine residue. The adenylate group is then transferred to the 5′-phosphate terminus of the substrate, forming the capped structure 5′-(5′-diphosphoadenosine)-[DNA]. Finally, the enzyme catalyses a nucleophilic attack of the 3′-OH terminus on the capped terminus, which results in formation of the phosphodiester bond and release of the adenylate. Different from EC?6.5.1.1, DNA ligase (ATP), EC?6.5.1.2, DNA ligase (NAD+) and EC?6.5.1.7, DNA ligase (ATP, ADP or GTP). |
