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Specific targeting of a plasmodesmal protein affecting cell-to-cell communication.

Thomas CL, Bayer EM, Ritzenthaler C, Fernandez-Calvino L, Maule AJ - PLoS Biol. (2008)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: John Innes Centre, Norwich Research Park, Colney, Norwich, United Kingdom.

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.

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Mutation Analysis of the Transmembrane Domain and Cytoplasmic Tail of PDLP1a(A and B) Multiple sequence alignment showing homology in the TMD within clade 1 of the PDLP1 family and greater variation in the cytoplasmic tail (CT) (A); the gene for PDLP1a is boxed. Deletions were made in the TMD and cytoplasmic tail (CT) of PDLP1a (B).(C) After transgenic expression in Arabidopsis, PDLP1aΔC:GFP deleted for the CT targeted to punctate structures in the cell wall.(D) In contrast, transgenic expression to produce PDLP1aΔC+:GFP deleted for the CT plus the three amino acids (LVL; underlined) at the end of the TMD, abolished punctate labelling in the cell wall and resulted in targeting to the ER.Bars indicate 10 μm.
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pbio-0060007-g007: Mutation Analysis of the Transmembrane Domain and Cytoplasmic Tail of PDLP1a(A and B) Multiple sequence alignment showing homology in the TMD within clade 1 of the PDLP1 family and greater variation in the cytoplasmic tail (CT) (A); the gene for PDLP1a is boxed. Deletions were made in the TMD and cytoplasmic tail (CT) of PDLP1a (B).(C) After transgenic expression in Arabidopsis, PDLP1aΔC:GFP deleted for the CT targeted to punctate structures in the cell wall.(D) In contrast, transgenic expression to produce PDLP1aΔC+:GFP deleted for the CT plus the three amino acids (LVL; underlined) at the end of the TMD, abolished punctate labelling in the cell wall and resulted in targeting to the ER.Bars indicate 10 μm.

Mentions: Bioinformatic analysis of the PDLP1 family clade 1 identified a common TMD of 21 amino acids upstream of a short but variable length C-terminal tail (Figure 7A). To assess the importance of the C-terminal tail in directing PDLP1a to plasmodesmata, this region was deleted (Figure 7B) and the resulting C-terminal fusion to GFP tested for targeting to plasmodesmata. Transient and transgenic expression showed that the protein lacking the C-terminal tail was still targeted to plasmodesmata (Figure 7C).


Specific targeting of a plasmodesmal protein affecting cell-to-cell communication.

Thomas CL, Bayer EM, Ritzenthaler C, Fernandez-Calvino L, Maule AJ - PLoS Biol. (2008)

Mutation Analysis of the Transmembrane Domain and Cytoplasmic Tail of PDLP1a(A and B) Multiple sequence alignment showing homology in the TMD within clade 1 of the PDLP1 family and greater variation in the cytoplasmic tail (CT) (A); the gene for PDLP1a is boxed. Deletions were made in the TMD and cytoplasmic tail (CT) of PDLP1a (B).(C) After transgenic expression in Arabidopsis, PDLP1aΔC:GFP deleted for the CT targeted to punctate structures in the cell wall.(D) In contrast, transgenic expression to produce PDLP1aΔC+:GFP deleted for the CT plus the three amino acids (LVL; underlined) at the end of the TMD, abolished punctate labelling in the cell wall and resulted in targeting to the ER.Bars indicate 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211546&req=5

pbio-0060007-g007: Mutation Analysis of the Transmembrane Domain and Cytoplasmic Tail of PDLP1a(A and B) Multiple sequence alignment showing homology in the TMD within clade 1 of the PDLP1 family and greater variation in the cytoplasmic tail (CT) (A); the gene for PDLP1a is boxed. Deletions were made in the TMD and cytoplasmic tail (CT) of PDLP1a (B).(C) After transgenic expression in Arabidopsis, PDLP1aΔC:GFP deleted for the CT targeted to punctate structures in the cell wall.(D) In contrast, transgenic expression to produce PDLP1aΔC+:GFP deleted for the CT plus the three amino acids (LVL; underlined) at the end of the TMD, abolished punctate labelling in the cell wall and resulted in targeting to the ER.Bars indicate 10 μm.
Mentions: Bioinformatic analysis of the PDLP1 family clade 1 identified a common TMD of 21 amino acids upstream of a short but variable length C-terminal tail (Figure 7A). To assess the importance of the C-terminal tail in directing PDLP1a to plasmodesmata, this region was deleted (Figure 7B) and the resulting C-terminal fusion to GFP tested for targeting to plasmodesmata. Transient and transgenic expression showed that the protein lacking the C-terminal tail was still targeted to plasmodesmata (Figure 7C).

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: John Innes Centre, Norwich Research Park, Colney, Norwich, United Kingdom.

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.

Show MeSH