The solution structure of functionally active human proliferating cell nuclear antigen determined by small-angle neutron scattering

J Mol Biol. 1998 Jan 9;275(1):123-32. doi: 10.1006/jmbi.1997.1435.


The function of proliferating cell nuclear antigen (PCNA) in DNA replication and repair is to form a sliding clamp with replication factor C (RF-C) tethering DNA polymerase delta or epsilon to DNA. In addition, PCNA has been found to interact directly with various proteins involved in cell cycle regulation. The crystal structure of yeast PCNA shows that the protein forms a homotrimeric ring lining a hole through which double-stranded DNA can thread, thus forming a moving platform for DNA synthesis. Human and yeast PCNA are highly conserved at a structural and functional level. We determined the solution structure of functionally active human PCNA by small-angle neutron scattering. Our measurements strongly support a trimeric ring-like structure of functionally active PCNA in solution, and the data are in good agreement with model calculations based on the crystal structure from yeast PCNA. The human PCNA used in the small-angle neutron scattering experiments was active before and after the measurements in a RF-C independent and a RF-C dependent assay suggesting that the trimeric structure is the in vivo functional form.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Buffers
  • DNA Replication
  • DNA-Binding Proteins / chemistry
  • Deuterium Oxide
  • Dialysis
  • Fourier Analysis
  • Homeodomain Proteins*
  • Humans
  • Minor Histocompatibility Antigens
  • Neutrons
  • Proliferating Cell Nuclear Antigen / chemistry*
  • Proliferating Cell Nuclear Antigen / metabolism
  • Proliferating Cell Nuclear Antigen / physiology*
  • Protein Conformation
  • Proto-Oncogene Proteins c-bcl-2*
  • Radiometry
  • Replication Protein C
  • Repressor Proteins*
  • Saccharomyces cerevisiae Proteins*
  • Scattering, Radiation
  • Solutions


  • BCL2-related protein A1
  • Buffers
  • DNA-Binding Proteins
  • Homeodomain Proteins
  • MATA1 protein, S cerevisiae
  • Minor Histocompatibility Antigens
  • Proliferating Cell Nuclear Antigen
  • Proto-Oncogene Proteins c-bcl-2
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • Solutions
  • Replication Protein C
  • Deuterium Oxide