T4 DNA ligase modulates chromosome damage induced by restriction endonucleases through an error-free process.

The possible modulation by T4 DNA ligase of the DNA double-strand breaks produced by restriction endonucleases in living mammalian cells was studied. A clear decrease in the frequency of chromosomal aberrations was observed when T4 DNA ligase was included in the electroporation treatment along with restriction enzymes inducing either cohesive- or blunt-ends in DNA. The relative proportions of exchange-type aberrations were similar for both kinds of treatments (with and without ligase), which seems to suggest an error-free ligation by T4 DNA ligase.