title: Arabidopsis AtCUL3a and AtCUL3b form complexes with members of the BTB/POZ-MATH protein family.
abstract: The ubiquitin proteasome pathway in plants has been shown to be important for many developmental processes. The E3 ubiquitin-protein ligases facilitate transfer of the ubiquitin moiety to substrate proteins. Many E3 ligases contain cullin proteins as core subunits. Here, we show that Arabidopsis (Arabidopsis thaliana) AtCUL3 proteins interact in yeast two-hybrid and in vitro pull-down assays with proteins containing a BTB/POZ (broad complex, tramtrack, bric-a-brac/pox virus and zinc finger) motif. By changing specific amino acid residues within the proteins, critical parts of the cullin and BTB/POZ proteins are defined that are required for these kinds of interactions. In addition, we show that AtCUL3 proteins assemble with the RING-finger protein AtRBX1 and are targets for the RUB-conjugation pathway. The analysis of AtCUL3a and AtCUL3b expression as well as several BTB/POZ-MATH genes indicates that these genes are expressed in all parts of the plant. The results presented here provide strong evidence that AtCUL3a and AtCUL3b can assemble in Arabidopsis with BTB/POZ-MATH and AtRBX1 proteins to form functional E3 ligases.
authors.affiliation: Angewandte Genetik, Freie Universität Berlin, 14195 Berlin, Germany.
authors.forename: Henriette
authors.initials: H
authors.lastname: Weber
authors.forename: Anne
authors.initials: A
authors.lastname: Bernhardt
authors.forename: Monika
authors.initials: M
authors.lastname: Dieterle
authors.forename: Perdita
authors.initials: P
authors.lastname: Hano
authors.forename: Aysegül
authors.initials: A
authors.lastname: Mutlu
authors.forename: Mark
authors.initials: M
authors.lastname: Estelle
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
authors.forename: Hanjo
authors.initials: H
authors.lastname: Hellmann
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D044842:Cullin Proteins / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D044842:Cullin Proteins; D046912:Multiprotein Complexes