LigD

LigD is a multifunctional ligase/polymerase/nuclease (3'-phosphoesterase) found in bacterial non-homologous end joining (NHEJ) DNA repair systems.^[1] It is much more error-prone than the more complex eukaryotic system of NHEJ, which uses multiple enzymes to fill its role.^[2] The polymerase preferentially use rNTPs (RNA nucleotides), possibly advantageous in dormant cells.^[3]

Multifunctional non-homologous end joining protein LigD
Identifiers
Organism	Mycolicibacterium smegmatis ATCC 700084
Symbol	ligD
UniProt	A0R3R7
Search for Structures Swiss-model Domains InterPro

The actual architecture of LigD is variable.

• The LigD homolog in Bacillus subtilis does not have the nuclease domain.
• LigD with its ligase domain artificially removed can perform its function (with loss of fidelity) with a separate LigC acting as the ligase.^[2]
• The LigD homolog in the archaeon Methanocella paludicola is broken into three single-domain proteins sharing an operon.^[4]