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An accessory protein enhances both DNA binding and activity of DNA polymerase alpha isolated from normal, but not

M Schroeder1, S Miller, V Srivastava

  • 1Department of Anatomy and Public Health, College of Veterinary Medicine, Texas A & M University, College Station 77843, USA.

Mutation Research
|May 1, 1996
PubMed

Insights

Aging human cells show reduced DNA polymerase alpha/primase (pol alpha) activity, linked to lower DNA binding. This decline may stem from decreased interaction with the pol alpha accessory protein (alpha AP).

Area of Science:

  • Molecular Biology
  • Cellular Aging
  • Enzymology

Background:

  • DNA polymerase alpha/primase (pol alpha) is crucial for DNA replication.
  • Cellular aging is often associated with decreased proliferative capacity and DNA synthesis.
  • The role of pol alpha activity and its accessory proteins in cellular senescence is not fully understood.

Purpose of the Study:

  • To investigate the specific activity and DNA binding properties of pol alpha from aged human fibroblasts.
  • To compare pol alpha from aged cells with that from young or transformed cells.
  • To explore the influence of the pol alpha accessory protein (alpha AP) on pol alpha function in aged cells.

Main Methods:

  • Isolation and characterization of DNA polymerase alpha/primase from human fibroblast cell lines (GM3529, WI38, GM3529T).
  • Assays for pol alpha specific activity and DNA binding affinity using SV40 DNA and non-specific DNA.
  • Treatment with purified pol alpha accessory protein (alpha AP) to assess its effect on pol alpha activity and DNA binding.

Main Results:

  • Pol alpha from aged fibroblasts (GM3529) showed decreased specific activity and DNA binding compared to fetal fibroblasts (WI38) or transformed cells (GM3529T).
  • Transformed cells (GM3529T) expressing SV40 large tumor antigen (TAg) had significantly higher pol alpha activity.
  • Alpha AP treatment increased the activity and DNA binding of pol alpha from aged cells but not from transformed cells.

Conclusions:

  • Decreased pol alpha specific activity in aged cells correlates with reduced proliferative capacity and DNA synthesis.
  • The reduced interaction between pol alpha and alpha AP may contribute to the diminished DNA binding affinity and activity observed in aged cells.
  • These findings suggest a potential mechanism for age-related decline in DNA replication fidelity and efficiency.

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