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Absence of accessory subunit in the DNA polymerase gamma purified from yeast mitochondria

Patrick Lucas1, Jean-Paul Lasserre, Jacqueline Plissonneau

  • 1Laboratoire Reger, UMR 5097, Université Victor Segalen Bordeaux 2, Bâtiment 3A, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.

Mitochondrion
|August 27, 2005
PubMed

Insights

Yeast mitochondrial DNA polymerase gamma has a single subunit, unlike the two-subunit enzyme found in animals. This study identifies the catalytic polypeptide and its molecular weight, revealing structural differences in mitochondrial genome replication.

Area of Science:

  • Mitochondrial DNA replication
  • Molecular biology
  • Enzymology

Background:

  • Mitochondrial genome replication in yeast and animals relies on DNA polymerase gamma.
  • Mammalian DNA polymerase gamma comprises catalytic and accessory subunits.
  • Understanding the structure of yeast DNA polymerase gamma is crucial for comparative genomics.

Purpose of the Study:

  • To characterize the subunit composition and quaternary structure of yeast DNA polymerase gamma.
  • To identify the catalytic subunit of yeast DNA polymerase gamma.
  • To compare the structure of yeast DNA polymerase gamma with its mammalian counterpart.

Main Methods:

  • Mitochondrial DNA polymerase gamma was purified from yeast.
  • Photochemical crosslinking was used to identify the catalytic polypeptide.
  • Gel filtration and glycerol gradient sedimentation were employed to estimate native molecular weight.

Main Results:

  • Yeast DNA polymerase gamma was purified over 6600-fold.
  • The catalytic polypeptide was identified as a 135-kDa protein.
  • Native molecular weight was estimated between 120 and 140 kDa, indicating a single subunit structure.

Conclusions:

  • Yeast DNA polymerase gamma exists as a single-subunit enzyme.
  • This contrasts with the two-subunit structure of mammalian DNA polymerase gamma.
  • Structural differences may impact mitochondrial genome replication mechanisms.

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