Conserved CDC20 cell cycle functions are carried out by two of the five isoforms in Arabidopsis thaliana

• Published in: PloS one Vol. 6; no. 6; p. e20618
• Main Authors: Kevei, Zoltán, Baloban, Mikhail, Da Ines, Olivier, Tiricz, Hilda, Kroll, Alexandra, Regulski, Krzysztof, Mergaert, Peter, Kondorosi, Eva
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08-06-2011; Public Library of Science (PLoS)
• Subjects: Agrobacterium; Amino Acid Sequence; Anaphase; Anaphase-promoting complex; Anaphase-Promoting Complex-Cyclosome; Arabidopsis; Arabidopsis - cytology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biodegradation; Biology; Biotechnology; CDC20 gene; Cdc20 Proteins; Cell cycle; Cell Cycle - genetics; Cell Cycle Proteins - chemistry; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cell number; Cell size; Chromosomes; Cyclins; Cyclins - metabolism; Deoxyribonucleic acid; DNA; Down-Regulation; E-cadherin; Enzymes; Gene expression; Gene Expression Regulation, Plant; Genes; Genetics; Genomes; Genomics; Intracellular Space - metabolism; Isoforms; Kinases; Life Sciences; Ligases; Male sterility; Meristems; Mitosis - genetics; Molecular Sequence Data; Mutagenesis; Phosphorylation; Phylogeny; Plant breeding; Plant growth; Plant Infertility - genetics; Plants genetics; Ploidy; Pollen; Primordia; Protein Isoforms - chemistry; Protein Isoforms - genetics; Protein Isoforms - metabolism; Protein Transport; Proteins; Pseudogenes; Regulators; RNA-mediated interference; Securin; Seeds; Substrates; Trends; Ubiquitin; Ubiquitin-protein ligase; Ubiquitin-Protein Ligase Complexes - metabolism; Vegetal Biology; Xenopus; Yeasts; Hungary; France
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0020618

The CDC20 and Cdh1/CCS52 proteins are substrate determinants and activators of the Anaphase Promoting Complex/Cyclosome (APC/C) E3 ubiquitin ligase and as such they control the mitotic cell cycle by targeting the degradation of various cell cycle regulators. In yeasts and animals the main CDC20 function is the destruction of securin and mitotic cyclins. Plants have multiple CDC20 gene copies whose functions have not been explored yet. In Arabidopsis thaliana there are five CDC20 isoforms and here we aimed at defining their contribution to cell cycle regulation, substrate selectivity and plant development.
Studying the gene structure and phylogeny of plant CDC20s, the expression of the five AtCDC20 gene copies and their interactions with the APC/C subunit APC10, the CCS52 proteins, components of the mitotic checkpoint complex (MCC) and mitotic cyclin substrates, conserved CDC20 functions could be assigned for AtCDC20.1 and AtCDC20.2. The other three intron-less genes were silent and specific for Arabidopsis. We show that AtCDC20.1 and AtCDC20.2 are components of the MCC and interact with mitotic cyclins with unexpected specificity. AtCDC20.1 and AtCDC20.2 are expressed in meristems, organ primordia and AtCDC20.1 also in pollen grains and developing seeds. Knocking down both genes simultaneously by RNAi resulted in severe delay in plant development and male sterility. In these lines, the meristem size was reduced while the cell size and ploidy levels were unaffected indicating that the lower cell number and likely slowdown of the cell cycle are the cause of reduced plant growth.
The intron-containing CDC20 gene copies provide conserved and redundant functions for cell cycle progression in plants and are required for meristem maintenance, plant growth and male gametophyte formation. The Arabidopsis-specific intron-less genes are possibly "retrogenes" and have hitherto undefined functions or are pseudogenes.