Roles of PCNA-binding and ubiquitin-binding domains in human DNA polymerase eta in translesion DNA synthesis

Proc Natl Acad Sci U S A. 2008 Nov 18;105(46):17724-9. doi: 10.1073/pnas.0809844105. Epub 2008 Nov 10.


Treatment of yeast and human cells with DNA-damaging agents elicits Rad6-Rad18-mediated monoubiquitination of proliferating cell nuclear antigen (PCNA) at its Lys-164 residue [ubiquitin (Ub)-PCNA], and this PCNA modification is indispensable for promoting the access of translesion synthesis (TLS) polymerases (Pols) to PCNA. However, the means by which K164-linked Ub modulates the proficiency of TLS Pols to bind PCNA and take over synthesis from the replicative Pol has remained unclear. One model that has gained considerable credence is that the TLS Pols bind PCNA at 2 sites, to the interdomain connector loop via their PCNA-interacting protein (PIP) domain and to the K164-linked Ub moiety via their Ub-binding domain (UBD). Specifically, this model postulates that the UBD-mediated binding of TLS Pols to the Ub moiety on PCNA is necessary for TLS. To test the validity of this model, we examine the contributions that the PIP and Ub-binding zinc finger (UBZ) domains of human Poleta make to its functional interaction with PCNA, its colocalization with PCNA in replication foci, and its role in TLS in vivo. We conclude from these studies that the binding to PCNA via its PIP domain is a prerequisite for Poleta's ability to function in TLS in human cells and that the direct binding of the Ub moiety on PCNA via its UBZ domain is not required. We discuss the possible role of the Ub moiety on PCNA in TLS.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • DNA / biosynthesis*
  • DNA Mutational Analysis
  • DNA Replication
  • DNA-Directed DNA Polymerase / chemistry*
  • DNA-Directed DNA Polymerase / metabolism*
  • Humans
  • Molecular Sequence Data
  • Mutant Proteins / chemistry
  • Mutant Proteins / metabolism
  • Mutation / genetics
  • Proliferating Cell Nuclear Antigen / metabolism*
  • Protein Binding
  • Protein Structure, Tertiary
  • Structure-Activity Relationship
  • Ubiquitin / metabolism*


  • Mutant Proteins
  • Proliferating Cell Nuclear Antigen
  • Ubiquitin
  • DNA
  • DNA-Directed DNA Polymerase
  • Rad30 protein