title: Two classes of the CDh1-type activators of the anaphase-promoting complex in plants: novel functional domains and distinct regulation.
abstract: The Cdc20 and Cdh1/Fzr proteins are the substrate-specific activators of the anaphase-promoting complex (APC). In Medicago truncatula, the MtCcs52A and MtCcs52B proteins represent two subgroups of the Cdh1-type activators, which display differences in their cell cycle regulation, structure, and function. The ccs52A transcripts are present in all phases of the cell cycle. By contrast, expression of ccs52B is restricted to late G2-phase and M-phase, and its induced overexpression in BY2 cells inhibited mitosis. MtCcs52A is active in Schizosaccharomyces pombe and binds to the S. pombe APC, whereas MtCcs52B does not because of differences in the N-terminal region. We identified a new functional domain, the Cdh1-specific motif conserved in the Cdh1 proteins that, in addition to the C-box and the terminal Ile and Arg residues, was essential for the activity and required for efficient binding to the APC. Moreover, we demonstrate that cyclin-dependent kinase phosphorylation sites adjacent to the C-box may regulate the interaction with the APC. In the different plant organs, the expression of Mtccs52A and Mtccs52B displayed differences and indicated the involvement of the APC in differentiation processes.
authors.affiliation: Institut des Sciences du Végétal, 91198 Gif-sur-Yvette, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Tarayre
authors.forename: José Maria
authors.initials: JM
authors.lastname: Vinardell
authors.forename: Angel
authors.initials: A
authors.lastname: Cebolla
authors.forename: Adam
authors.initials: A
authors.lastname: Kondorosi
authors.forename: Eva
authors.initials: E
authors.lastname: Kondorosi
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D029902:Medicago / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics* / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D018844:Cyclin-Dependent Kinases