Two cell-cycle regulated SET-domain proteins interact with proliferating cell nuclear antigen (PCNA) in Arabidopsis

Plant J. 2006 Aug;47(3):395-407. doi: 10.1111/j.1365-313X.2006.02799.x. Epub 2006 Jun 12.


The proliferating cell nuclear antigen (PCNA) functions as a sliding clamp for DNA polymerase, and is thus a key actor in DNA replication. It is also involved in DNA repair, maintenance of heterochromatic regions throughout replication, cell cycle regulation and programmed cell death. Identification of PCNA partners is therefore necessary for understanding these processes. Here we identify two Arabidopsis SET-domain proteins that interact with PCNA: ATXR5 and ATXR6. A truncated ATXR5Deltaex2, incapable of interacting with PCNA, also occurs in planta. ATXR6, upregulated during the S phase, is upregulated by AtE2F transcription factors, suggesting that it is required for S-phase progression. The two proteins differ in their subcellular localization: ATXR5 has a dual localization in plastids and in the nucleus, whereas ATXR6 is solely nuclear. This indicates that the two proteins may play different roles in plant cells. However, overexpression of either ATXR5 or ATXR6 causes male sterility because of the degeneration of defined cell types. Taken together, our results suggest that both proteins may play a role in the cell cycle or DNA replication, and that the activity of ATXR5 may be regulated via its subcellular localization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Arabidopsis / cytology
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cell Cycle / physiology*
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Nucleus / metabolism
  • Cell Proliferation
  • DNA Replication
  • E2F Transcription Factors / metabolism
  • E2F Transcription Factors / physiology
  • Flowers / growth & development
  • Flowers / metabolism
  • Gene Expression Regulation, Plant
  • Green Fluorescent Proteins / analysis
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Plant Infertility
  • Plastids / metabolism
  • Proliferating Cell Nuclear Antigen / metabolism*
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins / analysis
  • Two-Hybrid System Techniques


  • Arabidopsis Proteins
  • Cell Cycle Proteins
  • E2F Transcription Factors
  • Nuclear Proteins
  • Proliferating Cell Nuclear Antigen
  • Recombinant Fusion Proteins
  • XR5 protein, Arabidopsis
  • Green Fluorescent Proteins