The accessory subunit of DNA polymerase gamma is essential for mitochondrial DNA maintenance and development in Drosophila melanogaster

Proc Natl Acad Sci U S A. 2002 Apr 2;99(7):4483-8. doi: 10.1073/pnas.072664899. Epub 2002 Mar 26.


DNA polymerase gamma, Pol gamma, is the key replicative enzyme in animal mitochondria. The Drosophila enzyme is a heterodimer comprising catalytic and accessory subunits of 125 kDa and 35 kDa, respectively. Both subunits have been cloned and characterized in a variety of model systems, and genetic mutants of the catalytic subunit were first identified in Drosophila, as chemically induced mutations that disrupt larval behavior (tamas). Mutations in the gene encoding the accessory subunit have not yet been described in any organism. Here, we report the consequences of null mutations upon mitochondrial DNA (mtDNA) replication and morphology, cell proliferation, and organismal viability. Mutations in the accessory subunit cause lethality during early pupation, concomitant with loss of mtDNA and mitochondrial mass, and reduced cell proliferation in the central nervous system. Surprisingly, the function of the central nervous system and muscle, as assessed in a locomotion assay, are only marginally affected. This finding is in contrast to our previous findings that disruption in the function of the catalytic subunit causes severe reduction in larval locomotion. We discuss our results in the context of current hypotheses for the function of the accessory subunit in mtDNA replication.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Division
  • DNA Polymerase gamma
  • DNA Replication
  • DNA, Mitochondrial / chemistry
  • DNA, Mitochondrial / genetics*
  • DNA-Directed DNA Polymerase / chemistry
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / physiology*
  • Drosophila melanogaster / genetics*
  • Drosophila melanogaster / physiology
  • Larva / physiology
  • Mitochondria / pathology*
  • Molecular Sequence Data
  • Protein Subunits


  • DNA, Mitochondrial
  • Protein Subunits
  • DNA Polymerase gamma
  • DNA-Directed DNA Polymerase