Crystal Structure of the Eukaryotic DNA Polymerase Processivity Factor PCNA

Cell. 1994 Dec 30;79(7):1233-43. doi: 10.1016/0092-8674(94)90014-0.


The crystal structure of the processivity factor required by eukaryotic DNA polymerase delta, proliferating cell nuclear antigen (PCNA) from S. cerevisiae, has been determined at 2.3 A resolution. Three PCNA molecules, each containing two topologically identical domains, are tightly associated to form a closed ring. The dimensions and electrostatic properties of the ring suggest that PCNA encircles duplex DNA, providing a DNA-bound platform for the attachment of the polymerase. The trimeric PCNA ring is strikingly similar to the dimeric ring formed by the beta subunit (processivity factor) of E. coli DNA polymerase III holoenzyme, with which it shares no significant sequence identity. This structural correspondence further substantiates the mechanistic connection between eukaryotic and prokaryotic DNA replication that has been suggested on biochemical grounds.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Biopolymers / chemistry
  • Crystallography, X-Ray
  • DNA-Binding Proteins / chemistry
  • DNA-Directed DNA Polymerase / metabolism*
  • Fungal Proteins / chemistry
  • Models, Molecular
  • Molecular Sequence Data
  • Proliferating Cell Nuclear Antigen / chemistry*
  • Protein Structure, Secondary
  • Saccharomyces cerevisiae / chemistry


  • Biopolymers
  • DNA-Binding Proteins
  • Fungal Proteins
  • Proliferating Cell Nuclear Antigen
  • DNA-Directed DNA Polymerase