Controlling the subcellular localization of DNA polymerases iota and eta via interactions with ubiquitin

EMBO J. 2006 Jun 21;25(12):2847-55. doi: 10.1038/sj.emboj.7601178. Epub 2006 Jun 8.


Y-family DNA polymerases have spacious active sites that can accommodate a wide variety of geometric distortions. As a consequence, they are considerably more error-prone than high-fidelity replicases. It is hardly surprising, therefore, that the in vivo activity of these polymerases is tightly regulated, so as to minimize their inadvertent access to primer-termini. We report here that one such mechanism employed by human cells relies on a specific and direct interaction between DNA polymerases iota and eta with ubiquitin (Ub). Indeed, we show that both polymerases interact noncovalently with free polyUb chains, as well as mono-ubiquitinated proliferating cell nuclear antigen (Ub-PCNA). Mutants of poliota (P692R) and poleta (H654A) were isolated that are defective in their interactions with polyUb and Ub-PCNA, whilst retaining their ability to interact with unmodified PCNA. Interestingly, the polymerase mutants exhibit significantly lower levels of replication foci in response to DNA damage, thereby highlighting the biological importance of the polymerase-Ub interaction in regulating the access of the TLS polymerases to stalled replication forks in vivo.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • DNA Polymerase iota
  • DNA-Directed DNA Polymerase / chemistry
  • DNA-Directed DNA Polymerase / metabolism*
  • Fibroblasts / cytology
  • Humans
  • Lysine / metabolism
  • Mutation / genetics
  • Proliferating Cell Nuclear Antigen / metabolism
  • Proteasome Endopeptidase Complex / metabolism
  • Protein Binding
  • Protein Interaction Mapping
  • Protein Transport
  • Two-Hybrid System Techniques
  • Ubiquitin / metabolism*
  • Zinc Fingers / genetics


  • Proliferating Cell Nuclear Antigen
  • Ubiquitin
  • DNA-Directed DNA Polymerase
  • Rad30 protein
  • Proteasome Endopeptidase Complex
  • Lysine
  • DNA Polymerase iota
  • POLI protein, human