In eukaryotes, the three families of ATP-dependent DNA ligases are associated with specific functions in DNA metabolism. DNA ligase I (LigI) catalyzes Okazaki-fragment ligation at the replication fork and nucleotide excision repair (NER). DNA ligase IV (LigIV) mediates repair of DNA double strand breaks (DSB) via non-homologous end-joining (NHEJ). The evolutionary younger DNA ligase III (LigIII) is restricted to higher eukaryotes and has been associated with base excision (BER) and single strand break repair (SSBR). We show that in vertebrate DT40 cells, in the absence of LigI, LigIII efficiently supports semi-conservative DNA replication via an alternative DNA replication pathway, as well as NER. LigIII also supports an alternative, low efficiency, NHEJ process that operates as backup to LigIV-dependent NHEJ. Together with its exclusive and essential function in mitochondria, these observations elevate LigIII to a universal ligase, equipped to substitute or backup the functions of all other DNA ligases.


Article metrics loading...

Loading full text...

Full text loading...

  • Received: 12 May 2012
  • Accepted: 12 May 2012
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error