The yeast analog of mammalian cyclin/proliferating-cell nuclear antigen interacts with mammalian DNA polymerase delta

Proc Natl Acad Sci U S A. 1988 Oct;85(20):7506-10. doi: 10.1073/pnas.85.20.7506.


DNA polymerase III from Saccharomyces cerevisiae is analogous to the mammalian DNA polymerase delta by several criteria, including an increased synthetic activity on poly(dA).oligo(dT) (40:1 nucleotide ratio) in the presence of calf thymus proliferating-cell nuclear antigen (PCNA), or cyclin. This stimulation assay has been used to purify the yeast analog of PCNA/cyclin (yPCNA) to homogeneity. yPCNA is a trimer or tetramer (Mr approximately 82,000) of identical subunits with a denatured Mr of 26,000. On a molar basis yPCNA and calf thymus PCNA/cyclin are equally active in stimulating DNA synthesis by DNA polymerase III. About 10 times more yPCNA than calf thymus PCNA/cyclin is needed, however, to stimulate calf thymus DNA polymerase delta, and the degree of stimulation obtained at saturating levels of yPCNA is a factor of 2-3 less than with calf thymus PCNA/cyclin. Both stimulatory proteins exert their effect in an identical fashion, i.e., by increasing the processivity of the DNA polymerase. Yeast DNA polymerases I and II and calf thymus DNA polymerase alpha are not stimulated by yPCNA. Treatment of logarithmic-phase cells with hydroxyurea blocks them in the S phase and produces a 4- to 5-fold increase in yPCNA.

Publication types

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

MeSH terms

  • Animals
  • Antigens, Fungal / isolation & purification
  • Cattle
  • Cell Cycle
  • DNA Polymerase III
  • DNA-Directed DNA Polymerase / metabolism*
  • Nuclear Proteins / isolation & purification
  • Nuclear Proteins / metabolism*
  • Proliferating Cell Nuclear Antigen
  • Saccharomyces cerevisiae / analysis*
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / immunology


  • Antigens, Fungal
  • Nuclear Proteins
  • Proliferating Cell Nuclear Antigen
  • DNA Polymerase III
  • DNA-Directed DNA Polymerase