Involved in ds DNA break (DSB) repair. Has a role in non-homologous integration (NHI) pathways where it is required in the final step of non-homologous end-joining (NHEJ). Not required for the repair of DSBs induced by ionizing radiation or UV light. Has an important role in morphogenesis, positively affecting the capacity to form hyphae. ATP + (deoxyribonucleotide)n-3'-hydroxyl + 5'-phospho-(deoxyribonucleotide)m = (deoxyribonucleotide)n+m + AMP + diphosphate. Cell cycle-regulated. Expression peaks in late G1 and during the morphological transition. Belongs to the ATP-dependent DNA ligase family.