Back to Search
Start Over
Crystal structure and nonhomologous end-joining function of the ligase component of Mycobacterium DNA ligase D.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2006 May 12; Vol. 281 (19), pp. 13412-13423. Date of Electronic Publication: 2006 Feb 13. - Publication Year :
- 2006
-
Abstract
- DNA ligase D (LigD) is a large polyfunctional enzyme involved in nonhomologous end-joining (NHEJ) in mycobacteria. LigD consists of a C-terminal ATP-dependent ligase domain fused to upstream polymerase and phosphoesterase modules. Here we report the 2.4 angstroms crystal structure of the ligase domain of Mycobacterium LigD, captured as the covalent ligase-AMP intermediate with a divalent metal in the active site. A chloride anion on the protein surface coordinated by the ribose 3'-OH and caged by arginine and lysine side chains is a putative mimetic of the 5'-phosphate at a DNA nick. Structure-guided mutational analysis revealed distinct requirements for the adenylylation and end-sealing reactions catalyzed by LigD. We found that a mutation of Mycobacterium LigD that ablates only ligase activity results in decreased fidelity of NHEJ in vivo and a strong bias of mutagenic events toward deletions instead of insertions at the sealed DNA ends. This phenotype contrasts with the increased fidelity of double-strand break repair in deltaligD cells or in a strain in which only the polymerase function of LigD is defective. We surmise that the signature error-prone quality of bacterial NHEJ in vivo arises from a dynamic balance between the end-remodeling and end-sealing steps.
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 281
- Issue :
- 19
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 16476729
- Full Text :
- https://doi.org/10.1074/jbc.M513550200