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
OrganismMycolicibacterium smegmatis ATCC 700084
SymbolligD
UniProtA0R3R7
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StructuresSwiss-model
DomainsInterPro

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]

References

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  1. ^ Della M, Palmbos PL, Tseng HM, et al. (October 2004). "Mycobacterial Ku and ligase proteins constitute a two-component NHEJ repair machine". Science. 306 (5696): 683–5. Bibcode:2004Sci...306..683D. doi:10.1126/science.1099824. PMID 15499016. S2CID 38823696.
  2. ^ a b Gong C, Bongiorno P, Martins A, et al. (April 2005). "Mechanism of nonhomologous end-joining in mycobacteria: a low-fidelity repair system driven by Ku, ligase D and ligase C". Nat. Struct. Mol. Biol. 12 (4): 304–12. doi:10.1038/nsmb915. PMID 15778718. S2CID 6879518.
  3. ^ Pitcher RS, Green AJ, Brzostek A, Korycka-Machala M, Dziadek J, Doherty AJ (September 2007). "NHEJ protects mycobacteria in stationary phase against the harmful effects of desiccation" (PDF). DNA Repair (Amst.). 6 (9): 1271–6. doi:10.1016/j.dnarep.2007.02.009. PMID 17360246.
  4. ^ Bartlett, EJ; Brissett, NC; Doherty, AJ (28 May 2013). "Ribonucleolytic resection is required for repair of strand displaced nonhomologous end-joining intermediates". Proceedings of the National Academy of Sciences of the United States of America. 110 (22): E1984-91. Bibcode:2013PNAS..110E1984B. doi:10.1073/pnas.1302616110. PMC 3670387. PMID 23671117.