摘要
Human mitochondrial DNA (mtDNA) polymerase 纬 (pol 纬) is the sole enzyme required to replicate and maintain the integrity of the mitochondrial genome. It comprises two subunits, a catalytic p140 subunit and a smaller p55 accessory subunit encoded by the POLG2 gene. We describe the molecular characterization of a potential dominant POLG2 mutation (p.R369G) in a patient with adPEO and multiple mtDNA deletions. Biochemical studies of the recombinant mutant p55 protein showed a reduced affinity to the pol 纬 p140 subunit, leading to impaired processivity of the holoenzyme complex but did not show sensitivity to N-ethylmalaimide (NEM) inhibition, inferring a novel disease mechanism.