title: Selective regulation of maize plasma membrane aquaporin trafficking and activity by the SNARE SYP121.
abstract: Plasma membrane intrinsic proteins (PIPs) are aquaporins facilitating the diffusion of water through the cell membrane. We previously showed that the traffic of the maize (Zea mays) PIP2;5 to the plasma membrane is dependent on the endoplasmic reticulum diacidic export motif. Here, we report that the post-Golgi traffic and water channel activity of PIP2;5 are regulated by the SNARE (for soluble N-ethylmaleimide-sensitive factor protein attachment protein receptor) SYP121, a plasma membrane resident syntaxin involved in vesicle traffic, signaling, and regulation of K(+) channels. We demonstrate that the expression of the dominant-negative SYP121-Sp2 fragment in maize mesophyll protoplasts or epidermal cells leads to a decrease in the delivery of PIP2;5 to the plasma membrane. Protoplast and oocyte swelling assays showed that PIP2;5 water channel activity is negatively affected by SYP121-Sp2. A combination of in vitro (copurification assays) and in vivo (bimolecular fluorescence complementation, Förster resonance energy transfer, and yeast split-ubiquitin) approaches allowed us to demonstrate that SYP121 and PIP2;5 physically interact. Together with previous data demonstrating the role of SYP121 in regulating K(+) channel trafficking and activity, these results suggest that SYP121 SNARE contributes to the regulation of the cell osmotic homeostasis.
authors.affiliation: Institut des Sciences de la Vie, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Besserer
authors.forename: Emeline
authors.initials: E
authors.lastname: Burnotte
authors.forename: Gerd Patrick
authors.initials: GP
authors.lastname: Bienert
authors.forename: Adrien S
authors.initials: AS
authors.lastname: Chevalier
authors.forename: Abdelmounaim
authors.initials: A
authors.lastname: Errachid
authors.forename: Christopher
authors.initials: C
authors.lastname: Grefen
authors.forename: Michael R
authors.initials: MR
authors.lastname: Blatt
authors.forename: François
authors.initials: F
authors.lastname: Chaumont
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D031541:Fluorescence Resonance Energy Transfer; D018506:Gene Expression Regulation, Plant; D006056:Golgi Apparatus / Q000378:metabolism; D006706:Homeostasis; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D058503:Mesophyll Cells / Q000378:metabolism; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D009995:Osmosis; D019441:Plant Epidermis / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D025941:Protein Interaction Mapping; D021381:Protein Transport; D011523:Protoplasts / Q000378:metabolism; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014867:Water / Q000378:metabolism; D014981:Xenopus / Q000235:genetics / Q000378:metabolism; D003313:Zea mays / Q000235:genetics / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D008565:Membrane Proteins; D010940:Plant Proteins; D015221:Potassium Channels; D050765:Qa-SNARE Proteins; D014867:Water