Two cell-cycle regulated SET-domain proteins interact with proliferating cell nuclear antigen (PCNA) in Arabidopsis
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 ATXR5Δex2, 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.
Document Type: Research Article
Affiliations: 1: Institut de Biotechnologies des Plantes, CNRS UMR 8618, Bâtiment 630, Université Paris-Sud XI, 91405 Orsay, France, 2: Department of Genetics and Microbiology, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy, and 3: Institut des Sciences du Végétal, CNRS UPR 2355, Avenue de la Terrasse, 91198 Gif-sur- Yvette, France
Publication date: August 1, 2006