Fidelity of DNA Ligase I is sensitive to physiological Mg2+ level

The pool of free intracellular Mg²⁺ varies among tissues with the highest concentration measured in muscle tissue and the lowest measured in immune cells and in the brain. Here we investigate the impact of free Mg²⁺ on the fidelity of human DNA ligase I (LIG1). LIG1 is the major DNA ligase and is required to complete DNA replication, recombination and repair pathways. Biallelic hypomorphic variants of LIG1 cause immunodeficiency-96 (IMD96). We employed steady-state kinetics