6p0c

Publication Abstract from PubMed

DNA ligases catalyze the joining of DNA strands to complete DNA replication, recombination and repair transactions. To protect the integrity of the genome, DNA ligase 1 (LIG1) discriminates against DNA junctions harboring mutagenic 3'-DNA mismatches or oxidative DNA damage, but how such high-fidelity ligation is enforced is unknown. Here, X-ray structures and kinetic analyses of LIG1 complexes with undamaged and oxidatively damaged DNA unveil that LIG1 employs Mg(2+)-reinforced DNA binding to validate DNA base pairing during the adenylyl transfer and nick-sealing ligation reaction steps. Our results support a model whereby LIG1 fidelity is governed by a high-fidelity (HiFi) interface between LIG1, Mg(2+), and the DNA substrate that tunes the enzyme to release pro-mutagenic DNA nicks. In a second tier of protection, LIG1 activity is surveilled by Aprataxin (APTX), which suppresses mutagenic and abortive ligation at sites of oxidative DNA damage.

Two-tiered enforcement of high-fidelity DNA ligation.,Tumbale PP, Jurkiw TJ, Schellenberg MJ, Riccio AA, O'Brien PJ, Williams RS Nat Commun. 2019 Nov 28;10(1):5431. doi: 10.1038/s41467-019-13478-7. PMID:31780661^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.