Interaction of human DNA polymerase eta with monoubiquitinated PCNA: a possible mechanism for the polymerase switch in response to DNA damage

Mol Cell. 2004 May 21;14(4):491-500. doi: 10.1016/s1097-2765(04)00259-x.


Most types of DNA damage block replication fork progression during DNA synthesis because replicative DNA polymerases are unable to accommodate altered DNA bases in their active sites. To overcome this block, eukaryotic cells employ specialized translesion synthesis (TLS) polymerases, which can insert nucleotides opposite damaged bases. In particular, TLS by DNA polymerase eta (poleta) is the major pathway for bypassing UV photoproducts. How the cell switches from replicative to TLS polymerase at the site of blocked forks is unknown. We show that, in human cells, PCNA becomes monoubiquitinated following UV irradiation of the cells and that this is dependent on the hRad18 protein. Monoubiquitinated PCNA but not unmodified PCNA specifically interacts with poleta, and we have identified two motifs in poleta that are involved in this interaction. Our findings provide an attractive mechanism by which monoubiquitination of PCNA might mediate the polymerase switch.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatin / genetics
  • Chromatin / radiation effects
  • DNA / biosynthesis
  • DNA / radiation effects
  • DNA Damage / genetics*
  • DNA Damage / radiation effects
  • DNA Replication / genetics
  • DNA Replication / radiation effects
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / metabolism*
  • Humans
  • Proliferating Cell Nuclear Antigen / genetics
  • Proliferating Cell Nuclear Antigen / metabolism*
  • Proliferating Cell Nuclear Antigen / radiation effects
  • Protein Structure, Tertiary / genetics
  • Protein Structure, Tertiary / radiation effects
  • Ubiquitin / genetics
  • Ubiquitin / metabolism*
  • Ubiquitin-Protein Ligases
  • Ultraviolet Rays


  • Chromatin
  • DNA-Binding Proteins
  • Proliferating Cell Nuclear Antigen
  • RAD18 protein, human
  • Ubiquitin
  • DNA
  • Ubiquitin-Protein Ligases
  • DNA-Directed DNA Polymerase
  • Rad30 protein