InterPro domain: IPR013839

DNA ligase (polydeoxyribonucleotide synthase) is the enzyme that joins two DNA fragments by catalyzing the formation of an internucleotide ester bond between phosphate and deoxyribose. It is active during DNA replication, DNA repair and DNA recombination. There are two forms of DNA ligase: one requires ATP ( 6.5.1.1 ), the other NAD ( 6.5.1.2 ).

This entry represents the N-terminal adenylation domain of NAD-dependent DNA ligases. These are proteins of about 75 to 85 Kd whose sequence is well conserved [ 1 , 2 ]. They also show similarity to yicF, an Escherichia coli hypothetical protein of 63 Kd. Despite a complete lack of detectable sequence similarity, the fold of the central core of this adenyaltion domain shares homology with the equivalent region of ATP-dependent DNA ligases [ 3 , 4 ].

1. Cloning and molecular characterization of the DNA ligase gene (lig) from Zymomonas mobilis. FEMS Microbiol. Lett. 75, 19-26
2. Guanylate kinase of Escherichia coli K-12. J. Biol. Chem. 268, 14316-21
3. Structure of the adenylation domain of an NAD+-dependent DNA ligase. Structure 7, 35-42
4. Crystal structure of NAD(+)-dependent DNA ligase: modular architecture and functional implications. EMBO J. 19, 1119-29