title: Arabidopsis has two redundant Cullin3 proteins that are essential for embryo development and that interact with RBX1 and BTB proteins to form multisubunit E3 ubiquitin ligase complexes in vivo.
abstract: Cullin-based E3 ubiquitin ligases play important roles in the regulation of diverse developmental processes and environmental responses in eukaryotic organisms. Recently, it was shown in Schizosaccharomyces pombe, Caenorhabditis elegans, and mammals that Cullin3 (CUL3) directly associates with RBX1 and BTB domain proteins in vivo to form a new family of E3 ligases, with the BTB protein subunit functioning in substrate recognition. Here, we demonstrate that Arabidopsis thaliana has two redundant CUL3 (AtCUL3) genes that are essential for embryo development. Besides supporting anticipated specific AtCUL3 interactions with the RING protein AtRBX1 and representative Arabidopsis proteins containing a BTB domain in vitro, we show that AtCUL3 cofractionates and specifically associates with AtRBX1 and a representative BTB protein in vivo. Similar to the AtCUL1 subunit of the SKP1-CUL1-F-box protein-type E3 ligases, the AtCUL3 subunit of the BTB-containing E3 ligase complexes is subjected to modification and possible regulation by the ubiquitin-like protein Related to Ubiquitin in vivo. Together with the presence of large numbers of BTB proteins with diverse structural features and expression patterns, our data suggest that Arabidopsis has conserved AtCUL3-RBX1-BTB protein E3 ubiquitin ligases to target diverse protein substrates for degradation by the ubiquitin/proteasome pathway.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Conecticut 06520-8104, USA.
authors.forename: Pablo
authors.initials: P
authors.lastname: Figueroa
authors.forename: Giuliana
authors.initials: G
authors.lastname: Gusmaroli
authors.forename: Giovanna
authors.initials: G
authors.lastname: Serino
authors.forename: Jessica
authors.initials: J
authors.lastname: Habashi
authors.forename: Ligeng
authors.initials: L
authors.lastname: Ma
authors.forename: Yunping
authors.initials: Y
authors.lastname: Shen
authors.forename: Suhua
authors.initials: S
authors.lastname: Feng
authors.forename: Magnolia
authors.initials: M
authors.lastname: Bostick
authors.forename: Judy
authors.initials: J
authors.lastname: Callis
authors.forename: Hanjo
authors.initials: H
authors.lastname: Hellmann
authors.forename: Xing Wang
authors.initials: XW
authors.lastname: Deng
mesh_terms: D017360:Arabidopsis / Q000196:embryology / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D044842:Cullin Proteins; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D046911:Macromolecular Substances / Q000378:metabolism; D008969:Molecular Sequence Data; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D012639:Seeds / Q000196:embryology / Q000201:enzymology* / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: C500789:AT1G26830 protein, Arabidopsis; D029681:Arabidopsis Proteins; C507150:At1g21780 protein, Arabidopsis; D002352:Carrier Proteins; D044842:Cullin Proteins; D046911:Macromolecular Substances; C507151:RBX1 protein, Arabidopsis; C479529:RBX1 protein, human; C500790:cullin 3B protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex