Open AccessOxidative damage diminishes mitochondrial DNA polymerase replication fidelity
Author(s) -
Andrew P Anderson,
Xi Luo,
William K. Russell,
Yajiang Yin
Publication year - 2019
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/gkz1018
Subject(s) - biology , processivity , dna polymerase , mitochondrial dna , dna replication , polymerase , dna polymerase delta , dna polymerase ii , microbiology and biotechnology , primer (cosmetics) , exonuclease , genetics , dna , gene , polymerase chain reaction , chemistry , reverse transcriptase , organic chemistry
Abstract Mitochondrial DNA (mtDNA) resides in a high ROS environment and suffers more mutations than its nuclear counterpart. Increasing evidence suggests that mtDNA mutations are not the results of direct oxidative damage, rather are caused, at least in part, by DNA replication errors. To understand how the mtDNA replicase, Pol γ, can give rise to elevated mutations, we studied the effect of oxidation of Pol γ on replication errors. Pol γ is a high fidelity polymerase with polymerase ( pol ) and proofreading exonuclease ( exo ) activities. We show that Pol γ exo domain is far more sensitive to oxidation than pol ; under oxidative conditions, exonuclease activity therefore declines more rapidly than polymerase. The oxidized Pol γ becomes editing-deficient, displaying a 20-fold elevated mutations than the unoxidized enzyme. Mass spectrometry analysis reveals that Pol γ exo domain is a hotspot for oxidation. The oxidized exo residues increase the net negative charge around the active site that should reduce the affinity to mismatched primer/template DNA. Our results suggest that the oxidative stress induced high mutation frequency on mtDNA can be indirectly caused by oxidation of the mitochondrial replicase.