Expression of CLAVATA3 fusions indicates rapid intracellular processing and a role of ERAD.
The 12 amino acid peptide derived from the Arabidopsis soluble secretory protein CLAVATA3 (CLV3) acts at the cell surface in a signalling system that regulates the size of apical meristems. The subcellular pathway involved in releasing the peptide from its precursor is unknown. We show that a CLV3-GFP fusion expressed in transfected tobacco protoplasts or transgenic tobacco plants has very short intracellular half-life that cannot be extended by the secretory traffic inhibitors brefeldin A and wortmannin. The fusion is biologically active, since the incubation medium of protoplasts from CLV3-GFP-expressing tobacco contains the CLV3 peptide and inhibits root growth. The rapid disappearance of intact CLV3-GFP requires the signal peptide and is inhibited by the proteasome inhibitor MG132 or coexpression with a mutated CDC48 that inhibits endoplasmic reticulum-associated protein degradation (ERAD). The synthesis of CLV3-GFP is specifically supported by the endoplasmic reticulum chaperone endoplasmin in an in vivo assay. Our results indicate that processing of CLV3 starts intracellularly in an early compartment of the secretory pathway and that ERAD could play a regulatory or direct role in the active peptide synthesis.
['De Marchis|Francesca|F|', 'Colanero|Sara|S|', 'Klein|Eva M|EM|', 'Mainieri|Davide|D|', 'Prota|Viviana M|VM|', 'Bellucci|Michele|M|', 'Pagliuca|Giampiero|G|', 'Zironi|Elisa|E|', 'Gazzotti|Teresa|T|', 'Vitale|Alessandro|A|', 'Pompa|Andrea|A|']
D017360:Arabidopsis D029681:Arabidopsis Proteins D060746:Endoplasmic Reticulum-Associated Degradation D008856:Microscopy, Fluorescence D030821:Plants, Genetically Modified D013347:Subcellular Fractions D014026:Tobacco
CLAVATA3 Erad Endoplasmin Arabidopsis thaliana Protein processing Protein traffic