Essential interaction between the fission yeast DNA polymerase delta subunit Cdc27 and Pcn1 (PCNA) mediated through a C-terminal p21(Cip1)-like PCNA binding motif

EMBO J. 2000 Mar 1;19(5):1108-18. doi: 10.1093/emboj/19.5.1108.


Direct interaction between DNA polymerase delta and its processivity factor proliferating cell nuclear antigen (PCNA) is essential for effective replication of the eukaryotic genome, yet the precise manner by which this occurs is unclear. We show that the 54 kDa subunit of DNA polymerase delta from Schizosaccharomyces pombe interacts directly with Pcn1 (PCNA) both in vivo and in vitro. Binding is effected via a short sequence at the C-terminus of Cdc27 with significant similarity to the canonical PCNA binding motif first identified in the mammalian p21(Cip1) protein. This motif is both necessary and sufficient for binding of Pcn1 by Cdc27 in vitro and is essential for Cdc27 function in vivo. We also show that the Pcn1 binding motif in Cdc27 is distinct from its binding site for Cdc1, the 55 kDa B-subunit of polymerase delta, and present evidence that Cdc27 can bind to Pcn1 and Cdc1 simultaneously. Finally, we show that Cdc27 performs at least two distinct essential functions, one of which is independent of Pcn1 binding.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome
  • Binding Sites
  • Cell Cycle Proteins / metabolism*
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins / metabolism*
  • DNA Polymerase III / metabolism*
  • Molecular Sequence Data
  • Proliferating Cell Nuclear Antigen / metabolism*
  • Protein Binding
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins
  • Schizosaccharomyces pombe Proteins
  • Sequence Alignment
  • Signal Transduction
  • Ubiquitin-Protein Ligases


  • Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome
  • CDC27 protein, S cerevisiae
  • Cell Cycle Proteins
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • Proliferating Cell Nuclear Antigen
  • Saccharomyces cerevisiae Proteins
  • Schizosaccharomyces pombe Proteins
  • cdc27 protein, S pombe
  • Ubiquitin-Protein Ligases
  • DNA Polymerase III