title: SUPPRESSOR OF LLP1 1-mediated C-terminal processing is critical for CLE19 peptide activity.
abstract: Cell-to-cell communication is essential for the coordinated development of multicellular organisms. Members of the CLAVATA3/EMBRYO-SURROUNDING REGION-RELATED (CLE) family, a group of small secretory peptides, are involved in these processes in plants. Although post-translational modifications are considered to be indispensable for their activity, the detailed mechanisms governing these modifications are not well understood. Here, we report that SUPPRESSOR OF LLP1 1 (SOL1), a putative Zn²⁺ carboxypeptidase previously isolated as a suppressor of the CLE19 over-expression phenotype, functions in C-terminal processing of the CLE19 proprotein to produce the functional CLE19 peptide. Newly isolated sol1 mutants are resistant to CLE19 over-expression, consistent with the previous report (Casamitjana-Martinez, E., Hofhuis, H.F., Xu, J., Liu, C.M., Heidstra, R. and Scheres, B. (2003) Curr. Biol. 13, 1435-1441). As expected, our experiment using synthetic CLE19 peptide revealed that the sol1 mutation does not compromise CLE signal transduction pathways per se. SOL1 possesses enzymatic activity to remove the C-terminal arginine residue of CLE19 proprotein in vitro, and SOL1-dependent cleavage of the C-terminal arginine residue is necessary for CLE19 activity in vivo. Additionally, the endosomal localization of SOL1 suggests that this processing occurs in endosomes in the secretory pathway. Thus, our data indicate the importance of C-terminal processing of CLE proproteins to ensure CLE activities.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tamaki
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Betsuyaku
authors.forename: Masayuki
authors.initials: M
authors.lastname: Fujiwara
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Fukao
authors.forename: Hiroo
authors.initials: H
authors.lastname: Fukuda
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Sawa
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002268:Carboxypeptidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011992:Endosomes / Q000201:enzymology; D004967:Estrogens / Q000494:pharmacology; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D018519:Meristem / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010641:Phenotype; D018517:Plant Roots / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D018520:Plant Shoots / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; C483317:CLV3-ESR-related 19 protein, Arabidopsis; D004967:Estrogens; D002268:Carboxypeptidases
keywords: Arabidopsis thaliana; CLE peptide; CLE19; SOL1; carboxypeptidase; intercellular signaling; post-translational processing