Molecular and functional characterization of Arabidopsis Cullin 3A.
Cullin proteins, which belong to multigenic families in all eukaryotes, associate with other proteins to form ubiquitin protein ligases (E3s) that target substrates for proteolysis by the 26S proteasome. Here, we present the molecular and genetic characterization of a plant Cullin3. In contrast to fungi and animals, the genome of the model plant Arabidopsis thaliana contains two related CUL3 genes, called CUL3A and CUL3B. We found that CUL3A is ubiquitously expressed in plants and is able to interact with the ring-finger protein RBX1. A genomic search revealed the existence of at least 76 BTB-domain proteins in Arabidopsis belonging to 11 major families. Yeast two-hybrid experiments indicate that representative members of certain families are able to physically interact with both CUL3A and CUL3B, suggesting that Arabidopsis CUL3 forms E3 protein complexes with certain BTB domain proteins. In order to determine the function of CUL3A, we used a reverse genetic approach. The cul3a null mutant flowers slightly later than the control plants. Furthermore, this mutant exhibits a reduced sensitivity of the inhibition of hypocotyl growth in far-red light and miss-expresses COP1. The viability of the mutant plants suggests functional redundancy between the two CUL3 genes in Arabidopsis.
Dieterle
Monika
M
Institut de Biologie Moléculaire des Plantes du CNRS, 12, rue du Général Zimmer, 67084 Strasbourg cedex, France.
Thomann
Alexis
A
Renou
Jean-Pierre
JP
Parmentier
Yves
Y
Cognat
Valerie
V
Lemonnier
Gaetan
G
Müller
Rebecca
R
Shen
Wen-Hui
WH
Kretsch
Thomas
T
Genschik
Pascal
P
D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology; D044842:Cullin Proteins; D035264:Flowers; D018506:Gene Expression Regulation, Plant; D005801:Genes, Homeobox; D018546:Hypocotyl / Q000235:genetics / Q000502:physiology; D008027:Light; D005810:Multigene Family; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae; D020798:Two-Hybrid System Techniques
C500789:AT1G26830 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D044842:Cullin Proteins; C500790:cullin 3B protein, Arabidopsis