In
molecular biology,
DNA ligase is a specific type of enzyme, a
ligase, that facilitates the joining of
DNA strands together by catalyzing the formation of a
phosphodiester bond. It plays a role in repairing single-strand breaks in duplex
DNA in living organisms, but some forms (such as
DNA ligase IV) may specifically repair double-strand breaks (i.e. a break in both
complementary strands of DNA). Single-strand breaks are repaired by DNA ligase using the complementary strand of the double helix as a template, with DNA ligase creating the final phosphodiester bond to fully repair the DNA.