DNA ligases

Of particular interest are DNA ligases.

DNA ligases are important tools for DNA replication and repair in living organisms.

Enzymes called DNA ligases can rejoin cut or broken DNA strands.

The common commercially available DNA ligases were originally discovered in bacteriophage T4, E. coli and other bacteria.

DNA ligases have become an indispensable tool in modern molecular biology research for generating recombinant DNA sequences.

For example, DNA ligases are used with restriction enzymes to insert DNA fragments, often genes, into plasmids.

This contrasts with eukaryotic DNA ligases, which use ATP to form the DNA-AMP intermediate.

DNA ligase I is found in eukaryotes and therefore is in the family of ATP-dependent DNA ligases.

Of the known eukaryotic DNA ligases, DNA ligase I is the only ligase involved in DNA replication making it the most studied of the ligases.

DNA Ligases catalyze a couple of possible reactions that share a common feature: they join loose ends of DNA molecules, normally as part of a DNA repair process in the cell.

So far, we've discussed using DNA polymerase for sequencing reactions, but it's also possible to perform sequencing using DNA ligases, a technique pioneered by ABI's SOLiD technique.

TOPO cloning is a molecular biology technique in which DNA fragments amplified by either Taq or Pfu polymerases are cloned into specific vectors without the requirement for DNA ligases.

DNA ligases, that join broken DNA together, had been discovered earlier in 1967 and by combining the two enzymes it was possible to "cut and paste" DNA sequences to create recombinant DNA.

There are two families of DNA ligases, ATP-dependent DNA ligases and NAD dependent DNA ligases.

Both methods allow similarly large numbers of mutational variants to be simultaneously compared and competed, and both methods can potentially be adapted to a range of molecular biology enzymes that act on their own templates, such as restriction endonucleases or DNA ligases.