Localization of DNA polymerases eta and iota to the replication machinery is tightly co-ordinated in human cells

EMBO J. 2002 Nov 15;21(22):6246-56. doi: 10.1093/emboj/cdf618.


Y-family DNA polymerases can replicate past a variety of damaged bases in vitro but, with the exception of DNA polymerase eta (poleta), which is defective in xeroderma pigmentosum variants, there is little information on the functions of these polymerases in vivo. Here, we show that DNA polymerase iota (poliota), like poleta, associates with the replication machinery and accumulates at stalled replication forks following DNA-damaging treatment. We show that poleta and poliota foci form with identical kinetics and spatial distributions, suggesting that localization of these two polymerases is tightly co-ordinated within the nucleus. Furthermore, localization of poliota in replication foci is largely dependent on the presence of poleta. Using several different approaches, we demonstrate that poleta and poliota interact with each other physically and that the C-terminal 224 amino acids of poliota are sufficient for both the interaction with poleta and accumulation in replication foci. Our results provide strong evidence that poleta targets poliota to the replication machinery, where it may play a general role in maintaining genome integrity as well as participating in translesion DNA synthesis.

Publication types

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

MeSH terms

  • Active Transport, Cell Nucleus
  • Animals
  • Caffeine / toxicity
  • Cell Line
  • Cell Line, Transformed / drug effects
  • Cell Line, Transformed / radiation effects
  • Cell Nucleus / enzymology
  • DNA / drug effects
  • DNA / radiation effects
  • DNA Damage
  • DNA Polymerase iota
  • DNA Replication / physiology*
  • DNA-Directed DNA Polymerase / chemistry
  • DNA-Directed DNA Polymerase / deficiency
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / physiology*
  • Genes, Reporter
  • Genetic Complementation Test
  • Humans
  • Microscopy, Fluorescence
  • Protein Interaction Mapping
  • Recombinant Fusion Proteins / metabolism
  • Sequence Deletion
  • Spodoptera / cytology
  • Transfection
  • Two-Hybrid System Techniques
  • Ultraviolet Rays
  • Xeroderma Pigmentosum / enzymology
  • Xeroderma Pigmentosum / genetics
  • Xeroderma Pigmentosum / pathology


  • Recombinant Fusion Proteins
  • Caffeine
  • DNA
  • DNA-Directed DNA Polymerase
  • Rad30 protein
  • DNA Polymerase iota