Human Mitochondrial DNA Polymerase Metal Dependent UV Lesion Bypassing Ability

Joon Park, Noe Baruch-Torres, Shigenori Iwai, Geoffrey K. Herrmann, Luis G. Brieba, Y. Whitney Yin

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Human mitochondrial DNA contains more UV-induced lesions than the nuclear DNA due to lack of mechanism to remove bulky photoproducts. Human DNA polymerase gamma (Pol γ) is the sole DNA replicase in mitochondria, which contains a polymerase (pol) and an exonuclease (exo) active site. Previous studies showed that Pol γ only displays UV lesion bypassing when its exonuclease activity is obliterated. To investigate the reaction environment on Pol γ translesion activity, we tested Pol γ DNA activity in the presence of different metal ions. While Pol γ is unable to replicate through UV lesions on DNA templates in the presence of Mg2+, it exhibits robust translesion DNA synthesis (TLS) on cyclobutane pyrimidine dimer (CPD)-containing template when Mg2+ was mixed with or completely replaced by Mn2+. Under these conditions, the efficiency of Pol γ′s TLS opposite CPD is near to that on a non-damaged template and is 800-fold higher than that of exonuclease-deficient Pol γ. Interestingly, Pol γ exhibits higher exonuclease activity in the presence of Mn2+ than with Mg2+, suggesting Mn2+-stimulated Pol γ TLS is not via suppressing its exonuclease activity. We suggest that Mn2+ ion expands Pol γ′s pol active site relative to Mg2+ so that a UV lesion can be accommodated and blocks the communication between pol and exo active sites to execute translesion DNA synthesis.

Original languageEnglish (US)
Article number808036
JournalFrontiers in Molecular Biosciences
Volume9
DOIs
StatePublished - Mar 9 2022

Keywords

  • DNA polymerase gamma
  • TLS
  • UV lesion
  • metal-dependence
  • mitochondrial DNA

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)

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