Fidelity of the human mitochondrial DNA polymerase

J Biol Chem. 2006 Nov 24;281(47):36236-40. doi: 10.1074/jbc.M607964200. Epub 2006 Sep 27.


We have quantified the fidelity of polymerization of DNA by human mitochondrial DNA polymerase using synthetic DNA oligonucleotides and recombinant holoenzyme and examining each of the possible 16-base pair combinations. Although the kinetics of incorporation for all correct nucleotides are similar, with an average Kd of 0.8 microM and an average k(pol) of 37 s(-1), the kinetics of misincorporation vary widely. The ground state binding Kd of incorrect bases ranges from a low of 25 microM for a dATP:A mispair to a high of 360 microM for a dCTP:T mispair. Similarly, the rates of incorporation of incorrect bases vary from 0.0031 s(-1) for a dCTP:C mispair to 1.16 s(-1) for a dGTP:T mispair. Due to the variability in the kinetic parameters for misincorporation, the estimates of fidelity range from 1 error in 3563 nucleotides for dGTP:T to 1 error in 2.3 x 10(6) nucleotides for dCTP:C. Interestingly, the discrimination against a dGTP:T mismatch is 16.5 times lower than that of a dTTP:G mismatch due to a tighter Kd for ground state binding and a faster rate of incorporation of the dGTP:T mismatch relative to the dTTP:G mismatch. We calculate an average fidelity of 1 error in 440,000 nucleotides.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Monophosphate / chemistry
  • Adenosine Triphosphate / chemistry
  • Base Pair Mismatch
  • DNA / chemistry
  • DNA Repair
  • DNA, Mitochondrial / genetics
  • DNA-Directed DNA Polymerase / chemistry*
  • DNA-Directed DNA Polymerase / genetics*
  • Humans
  • Kinetics
  • Mitochondria / enzymology*
  • Mutation
  • Nucleotides / chemistry
  • Time Factors


  • DNA, Mitochondrial
  • Nucleotides
  • Adenosine Monophosphate
  • Adenosine Triphosphate
  • DNA
  • DNA-Directed DNA Polymerase