LIG3
Description
The LIG3 (DNA ligase 3) is a protein-coding gene located on chromosome 17.
LIG3 encodes ATP-dependent DNA ligases, essential for sealing breaks in the DNA backbone. It belongs to a family of DNA ligases less widespread than LIG1 and LIG4. LIG3 produces various DNA ligase forms through alternative translation initiation and splicing. The catalytic region of LIG3 contains three domains: a DNA binding domain, an adenylation domain, and an oligonucleotide/oligosaccharide binding-fold domain. These domains bind to DNA and facilitate the repair process. Notably, LIG3 has an N-terminal zinc finger, similar to PARP1, which aids in binding to DNA strand breaks. This zinc finger, in conjunction with the DNA binding domain, forms a DNA binding module. Additionally, the adenylation domain and oligonucleotide/oligosaccharide binding-fold domain create another DNA binding module.
Isoform 3 of LIG3 forms a complex with XRCC1 in the nucleus, playing a crucial role in repairing DNA strand breaks and preventing sister chromatid exchange following exposure to ionizing radiation or alkylating agents. Isoform 1, on the other hand, localizes to mitochondria and participates in mitochondrial base-excision DNA repair.
LIG3 is also known as LIG2, LIG3alpha, MTDPS20.
Associated Diseases
- Mitochondrial DNA depletion syndrome 20 (MNGIE type)
- Mitochondrial neurogastrointestinal encephalomyopathy
