Selective Regulation of Maize Plasma Membrane Aquaporin Trafficking and Activity by the SNARE SYP121

• Published in: The Plant cell Vol. 24; no. 8; pp. 3463 - 3481
• Main Authors: Besserer, Arnaud, Burnotte, Emeline, Bienert, Gerd Patrick, Chevalier, Adrien S., Errachid, Abdelmounaim, Grefen, Christopher, Blatt, Michael R., Chaumont, François
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01.08.2012
• Subjects: Amino Acid Sequence; Animals; Aquaporins; Aquaporins - genetics; Aquaporins - metabolism; Cell Membrane - metabolism; Cell membranes; Corn; Epidermal cells; Fluorescence; Fluorescence Recovery After Photobleaching; Fluorescence Resonance Energy Transfer; Gene Expression Regulation, Plant; Golgi Apparatus - metabolism; Homeostasis; Membrane Proteins - genetics; Membrane Proteins - metabolism; Mesophyll Cells - metabolism; Molecular Sequence Data; Oocytes; Oocytes - metabolism; Osmosis; Physiological regulation; Plant cells; Plant Epidermis - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Plasma interactions; Potassium Channels - genetics; Potassium Channels - metabolism; Protein Interaction Mapping; Protein Transport; Protoplasts; Protoplasts - metabolism; Qa-SNARE Proteins - genetics; Qa-SNARE Proteins - metabolism; Transfection; Water - metabolism; Xenopus - genetics; Xenopus - metabolism; Zea mays - genetics; Zea mays - metabolism
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.112.101758

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.