title: Arabidopsis ULTRAVIOLET-B-INSENSITIVE4 maintains cell division activity by temporal inhibition of the anaphase-promoting complex/cyclosome.
abstract: The anaphase-promoting complex/cyclosome (APC/C) is a multisubunit ubiquitin ligase that regulates progression through the cell cycle by marking key cell division proteins for destruction. To ensure correct cell cycle progression, accurate timing of APC/C activity is important, which is obtained through its association with both activating and inhibitory subunits. However, although the APC/C is highly conserved among eukaryotes, no APC/C inhibitors are known in plants. Recently, we have identified ULTRAVIOLET-B-INSENSITIVE4 (UVI4) as a plant-specific component of the APC/C. Here, we demonstrate that UVI4 uses conserved APC/C interaction motifs to counteract the activity of the CELL CYCLE SWITCH52 A1 (CCS52A1) activator subunit, inhibiting the turnover of the A-type cyclin CYCA2;3. UVI4 is expressed in an S phase-dependent fashion, likely through the action of E2F transcription factors. Correspondingly, uvi4 mutant plants failed to accumulate CYCA2;3 during the S phase and prematurely exited the cell cycle, triggering the onset of the endocycle. We conclude that UVI4 regulates the temporal inactivation of APC/C during DNA replication, allowing CYCA2;3 to accumulate above the level required for entering mitosis, and thereby regulates the meristem size and plant growth rate.
authors.affiliation: Department of Plant Systems Biology, VIB, Ghent, Belgium.
authors.forename: Jefri
authors.initials: J
authors.lastname: Heyman
authors.forename: Hilde
authors.initials: H
authors.lastname: Van den Daele
authors.forename: Kevin
authors.initials: K
authors.lastname: De Wit
authors.forename: Véronique
authors.initials: V
authors.lastname: Boudolf
authors.forename: Barbara
authors.initials: B
authors.lastname: Berckmans
authors.forename: Aurine
authors.initials: A
authors.lastname: Verkest
authors.forename: Claire Lessa
authors.initials: CL
authors.lastname: Alvim Kamei
authors.forename: Geert
authors.initials: G
authors.lastname: De Jaeger
authors.forename: Csaba
authors.initials: C
authors.lastname: Koncz
authors.forename: Lieven
authors.initials: L
authors.lastname: De Veylder
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D002455:Cell Division; D047369:Chromatin Immunoprecipitation; D056751:Cyclin A2 / Q000235:genetics / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism; D050684:E2F Transcription Factors / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D018519:Meristem / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D016297:Mutagenesis, Site-Directed; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D055550:Protein Stability; D016196:S Phase; D013329:Structure-Activity Relationship; D015533:Transcriptional Activation; D014170:Transformation, Genetic; D020798:Two-Hybrid System Techniques; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D056751:Cyclin A2; D050684:E2F Transcription Factors; C540491:FZR2 protein, Arabidopsis; C543427:cyclin A2;3 protein, Arabidopsis; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; C434472:CDKA1 protein, Arabidopsis; D018844:Cyclin-Dependent Kinases