title: Dimerization of the Vacuolar Receptors AtRMR1 and -2 from Arabidopsis thaliana Contributes to Their Localization in the trans-Golgi Network.
abstract: InArabidopsis thaliana, different types of vacuolar receptors were discovered. The AtVSR (Vacuolar Sorting Receptor) receptors are well known to be involved in the traffic to lytic vacuole (LV), while few evidences demonstrate the involvement of the receptors from AtRMR family (Receptor Membrane RING-H2) in the traffic to the protein storage vacuole (PSV). In this study we focused on the localization of two members of AtRMR family, AtRMR1 and -2, and on the possible interaction between these two receptors in the plant secretory pathway. Our experiments with agroinfiltratedNicotiana benthamianaleaves demonstrated that AtRMR1 was localized in the endoplasmic reticulum (ER), while AtRMR2 was targeted to thetrans-Golgi network (TGN) due to the presence of a cytosolic 23-amino acid sequence linker. The fusion of this linker to an equivalent position in AtRMR1 targeted this receptor to the TGN, instead of the ER. By using a Bimolecular Fluorescent Complementation (BiFC) technique and experiments of co-localization, we demonstrated that AtRMR2 can make homodimers, and can also interact with AtRMR1 forming heterodimers that locate to the TGN. Such interaction studies strongly suggest that the transmembrane domain and the few amino acids surrounding it, including the sequence linker, are essential for dimerization. These results suggest a new model of AtRMR trafficking and dimerization in the plant secretory pathway.
authors.affiliation: Plant Biology and Crop Science, Rothamsted Research, Harpenden, AL5 2JQ Herts, UK. alessandro.occhialini@rothamsted.ac.uk.|Laboratory of Cell and Molecular Biology, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2009 Neuchâtel, Switzerland. alessandro.occhialini@rothamsted.ac.uk.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Occhialini
authors.affiliation: Laboratory of Cell and Molecular Biology, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2009 Neuchâtel, Switzerland. guillaume.gouzerh@unine.ch.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Gouzerh
authors.affiliation: DISTEBA, Department of Biological and Environmental Sciences and Technologies, University of Salento, Campus Ecotekne, 73100 Lecce, Italy. gp.disansebastiano@unisalento.it.
authors.forename: Gian-Pietro
authors.initials: GP
authors.lastname: Di Sansebastiano
authors.affiliation: Laboratory of Cell and Molecular Biology, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2009 Neuchâtel, Switzerland. jean-marc.neuhaus@unine.ch.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Neuhaus
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D000072417:Protein Domains; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D010455:Peptides; C505135:RMR1 protein, Arabidopsis; D011993:Recombinant Fusion Proteins
keywords: Arabidopsis thaliana; AtRMR; Bimolecular Fluorescent Complementation; Nicotiana benthamiana; PA domain; RING-H2; Ser-Rich domain; dimerization; endoplasmic reticulum; laser scanning confocal microscopy; linker; plant secretory pathway; trans-Golgi network; transmembrane