Phosphorylation of the p68 subunit of Pol δ acts as a molecular switch to regulate its interaction with PCNA

Biochemistry. 2012 Jan 10;51(1):416-24. doi: 10.1021/bi201638e. Epub 2011 Dec 20.


DNA polymerase delta (Pol δ) is a central enzyme for eukaryotic DNA replication and repair. Pol δ is a complex of four subunits p125, p68, p50, and p12. The functional properties of Pol δ are largely determined by its interaction with its DNA sliding clamp PCNA (proliferating cellular nuclear antigen). The regulatory mechanisms that govern the association of Pol δ with PCNA are largely unknown. In this study, we identified S458, located in the PCNA-interacting protein (PIP-Box) motif of p68, as a phosphorylation site for PKA. Phosphomimetic mutation of S458 resulted in a decrease in p68 affinity for PCNA as well as the processivity of Pol δ. Our results suggest a role of phosphorylation of the PIP-motif of p68 as a molecular switch that dynamically regulates the functional properties of Pol δ.

Publication types

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

MeSH terms

  • Amino Acid Motifs / genetics
  • Amino Acid Sequence
  • Aspartic Acid / genetics
  • Cyclic AMP-Dependent Protein Kinases / chemistry
  • Cyclic AMP-Dependent Protein Kinases / physiology
  • DNA Polymerase III / antagonists & inhibitors
  • DNA Polymerase III / chemistry*
  • DNA Polymerase III / genetics
  • Down-Regulation / genetics
  • HeLa Cells
  • Humans
  • Molecular Mimicry / genetics
  • Molecular Sequence Data
  • Mutation
  • Phosphorylation / genetics
  • Proliferating Cell Nuclear Antigen / chemistry*
  • Proliferating Cell Nuclear Antigen / genetics
  • Proliferating Cell Nuclear Antigen / metabolism*
  • Protein Binding / genetics
  • Protein Processing, Post-Translational / genetics
  • Protein Subunits / antagonists & inhibitors
  • Protein Subunits / chemistry
  • Protein Subunits / genetics
  • Serine / genetics


  • Proliferating Cell Nuclear Antigen
  • Protein Subunits
  • Aspartic Acid
  • Serine
  • Cyclic AMP-Dependent Protein Kinases
  • DNA Polymerase III