Ligation (molecular biology)
From Wikipedia, the free encyclopedia
Ligation is the joining of two nucleic acid fragments through the action of an enzyme. It is an essential laboratory procedure in the molecular cloning of DNA, whereby DNA fragments are joined to create recombinant DNA molecules (such as when a foreign DNA fragment is inserted into a plasmid). The ends of DNA fragments are joined by the formation of phosphodiester bonds between the 3'-hydroxyl of one DNA terminus with the 5'-phosphoryl of another. RNA may also be ligated similarly. A co-factor is generally involved in the reaction, and this is usually ATP or NAD+. Eukaryotic cells ligases belong to ATP type, and NAD+ - dependent are found in bacteria (e.g. E. coli).[1]
The discovery of DNA ligase dates back to 1967 and is an important event in the field of molecular biology.[1] Ligation in the laboratory is normally performed using T4 DNA ligase. It is broadly used in vitro as molecular biology research tool due to its capability of joining as sticky as blunt DNA ends.[2] However, procedures for ligation without the use of standard DNA ligase are also popular. Human DNA ligases abnormalities have been linked to pathological disorders characterized by immunodeficiency, radiation sensitivity, and developmental problems.[3]