title: Specific targeting of a plasmodesmal protein affecting cell-to-cell communication.
abstract: Plasmodesmata provide the cytoplasmic conduits for cell-to-cell communication throughout plant tissues and participate in a diverse set of non-cell-autonomous functions. Despite their central role in growth and development and defence, resolving their modus operandi remains a major challenge in plant biology. Features of protein sequences and/or structure that determine protein targeting to plasmodesmata were previously unknown. We identify here a novel family of plasmodesmata-located proteins (called PDLP1) whose members have the features of type I membrane receptor-like proteins. We focus our studies on the first identified type member (namely At5g43980, or PDLP1a) and show that, following its altered expression, it is effective in modulating cell-to-cell trafficking. PDLP1a is targeted to plasmodesmata via the secretory pathway in a Brefeldin A-sensitive and COPII-dependent manner, and resides at plasmodesmata with its C-terminus in the cytoplasmic domain and its N-terminus in the apoplast. Using a deletion analysis, we show that the single transmembrane domain (TMD) of PDLP1a contains all the information necessary for intracellular targeting of this type I membrane protein to plasmodesmata, such that the TMD can be used to target heterologous proteins to this location. These studies identify a new family of plasmodesmal proteins that affect cell-to-cell communication. They exhibit a mode of intracellular trafficking and targeting novel for plant biology and provide technological opportunities for targeting different proteins to plasmodesmata to aid in plasmodesmal characterisation.
authors.affiliation: John Innes Centre, Norwich Research Park, Colney, Norwich, United Kingdom.
authors.forename: Carole L
authors.initials: CL
authors.lastname: Thomas
authors.forename: Emmanuelle M
authors.initials: EM
authors.lastname: Bayer
authors.forename: Christophe
authors.initials: C
authors.lastname: Ritzenthaler
authors.forename: Lourdes
authors.initials: L
authors.lastname: Fernandez-Calvino
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Maule
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002450:Cell Communication; D005109:Extracellular Matrix / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D031425:Plasmodesmata / Q000378:metabolism*; D021381:Protein Transport; D016415:Sequence Alignment; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C528450:PDLP1a protein, Arabidopsis