DNA Ligase 1 is an essential mediator of sister chromatid telomere fusions in G2 cell cycle phase. Homo sapiens

In this study, we sought to discriminate the relative contributions of these ligases for sister chromatid telomere fusion through a precise genetic dissociation of functional activity. We have resolved an essential and non-redundant role for DNA ligase 1 in the fusion of sister chromatids bearing targeted double strand DNA breaks that is entirely uncoupled from its requisite contribution to DNA replication. Importantly, this fusogenic repair is not compensated by DNA ligase 3 or 4 and occurs in cells fully proficient for non-homologous end-joining.