Jelle Van Leene, Jens Hollunder, Dominique Eeckhout, Geert Persiau, Eveline Van De Slijke, Hilde Stals, Gert Van Isterdael, Aurine Verkest, Sandy Neirynck, Yelle Buffel, Stefanie De Bodt, Steven Maere, Kris Laukens, Anne Pharazyn, Paulo C.G. Ferreira, Nubia Eloy, Charlotte Renne, Christian Meyer, Jean-Denis Faure, Jens Steinbrenner, Jim Beynon, John C. Larkin, Yves Van de Peer, Pierre Hilson, Martin Kuiper, Lieven De Veylder, Harry Van Onckelen, Dirk Inzé, Erwin Witters and Geert De Jaeger

Cell proliferation is the main driving force of plant growth. Although genome sequence analysis revealed a high number of cell cycle genes in plants, little is known about the molecular complexes steering cell division. In a targeted proteomics approach, we mapped the core complex machinery at the heart of the Arabidopsis thaliana cell cycle control. Besides a central regulatory network of core complexes, we distinguished a peripheral network that links the core machinery to up- and downstream pathways. Over 100 new candidate cell cycle proteins were predicted and an in-depth biological interpretation demonstrated the hypothesis-generating power of the interaction data. The dataset provided a comprehensive view on heterodimeric cyclin-dependent kinase (CDK)/cyclin complexes in plants. For the first time, inhibitory proteins of plant-specific B-type CDKs were discovered and the anaphase-promoting complex was characterized and extended. Important conclusions were that mitotic A- and B-type cyclins form complexes with the plant-specific B-type CDKs and not with CDKA;1, and that D-type cyclins and S-phase specific A-type cyclins are associated exclusively with CDKA;1. Furthermore, we could show that plants have evolved a combinatorial toolkit consisting of at least 92 different CDK/cyclin complex variants, which strongly underscores the functional diversification among the large family of cyclins and reflects the pivotal role of cell cycle regulation in the developmental plasticity of plants.

VIEW CELL CYCLE INTERACTOME (Cytoscape or Excel ) The complete cell cycle interactome as well as the following subnetworks are visualized in Cytoscape (Java Web Start needed for Cytoscape, download here).

• Cell cycle interactome
• I1 domain interactions
• I2 domain interactions
• Bait-bait interactions
• Bait-bait I1 domain interactions
• Bait-bait I2 domain interactions
• CDK/cyclin core complexes
• CDK/cyclin potential substrates
• Positive regulation by CAKs
• Negative regulation by KRPs
• Negative regulation by SIM/SMRs
• DNA replication complexes
• Anaphase promoting complex
• Spindle checkpoint complexes
• E2F motif network
• MSA motif network