Patellin1, a Novel Sec14-Like Protein, Localizes to the Cell Plate and Binds Phosphoinositides

Abstract

Membrane trafficking is central to construction of the cell plate during plant cytokinesis. Consequently, a detailed understanding of the process depends on the characterization of molecules that function in the formation, transport, targeting, and fusion of membrane vesicles to the developing plate, as well as those that participate in its consolidation and maturation into a fully functional partition. Here we report the initial biochemical and functional characterization of patellin1 (PATL1), a novel cell-plate-associated protein that is related in sequence to proteins involved in membrane trafficking in other eukaryotes. Analysis of the Arabidopsis genome indicated that PATL1 is one of a small family of Arabidopsis proteins, characterized by a variable N-terminal domain followed by two domains found in other membrane-trafficking proteins (Sec14 and Golgi dynamics domains). Results from immunolocalization and biochemical fractionation studies suggested that PATL1 is recruited from the cytoplasm to the expanding and maturing cell plate. In vesicle-binding assays, PATL1 bound to specific phosphoinositides, important regulators of membrane trafficking, with a preference for phosphatidylinositol(5)P, phosphatidylinositol(4,5)P2, and phosphatidylinositol(3)P. Taken together, these findings suggest a role for PATL1 in membrane-trafficking events associated with cell-plate expansion or maturation and point to the involvement of phosphoinositides in cell-plate biogenesis.

Extracellular Vesicles Isolated from the Leaf Apoplast Carry Stress-Response Proteins

“…PATL1 has been localized to the cell plate in dividing cells but also associates with PLASMODESMATA-LOCATED PROTEIN1 (PDLP1) during downy mildew infection and may colocalize with PDLP1 at the extrahaustorial membrane (Caillaud et al, 2014). We confirmed the presence of both PATL1 and PATL2 in the P40 fraction using anti-PATL antibodies (Peterman et al, 2004;Deng et al, 2007; Fig. 6A; Supplemental Fig.…”

“…Membranes were washed with 13 Tris-buffered saline (50 mM Tris-Cl and 150 mM NaCl, pH 7.5) containing 0.1% Tween 20 (TBST) and blocked with 5% Difco Skim Milk (BD) overnight at 4°C. Membranes were incubated with monoclonal mouse anti-GFP or anti-mCherry antibody (Abcam) at a 1:3,000 dilution or polyclonal anti-PATL1 (Peterman et al, 2004;Deng et al, 2007) at a 1:5,000 dilution for 1 h, washed with TBST, and incubated with horseradish peroxidase-labeled goat anti-mouse or anti-rabbit antibody (Abcam) at a 1:5,000 dilution for 1 h. After a final wash in TBST, protein bands were imaged using Immuno-Star Reagents (Bio-Rad) or Supersignal West Femto Maximum Sensitivity Substrates (Thermo Scientific) and x-ray film. Band intensities were quantified using the FlourChem E system with AlphaView SA software (version 3.4.0; ProteinSimple).…”

Response to biotic and oxidative stress in Arabidopsis thaliana: Analysis of variably phosphorylated proteins

“…Phosphorylated patellin-1 (spot 22) also showed a 7-fold up-regulation. This protein belongs to a small family of Sec14 and GOLD domains-containing lipidbinding proteins probably involved in membrane-trafficking events [44]; phosphoproteomic studies on membrane fractions of salt-stressed Arabidopsis demonstrated that patellin-2 phosphorylation levels raise upon stress [28]. Phosphorylated fibrillin-3 (spot 29) also showed increased levels.…”

A Laser Dissection-RNAseq Analysis Highlights the Activation of Cytokinin Pathways by Nod Factors in the Medicago truncatula Root Epidermis

“…We found here that MtAnn2 also is strongly, but transiently, up-regulated 4 h after NF treatment in epidermal cells (Table II). Two small GTPase Ras-related proteins, potentially involved in polarized membrane trafficking (Vernoud et al, 2003), and three patellins (Sec14 and GOLD domain proteins, also implicated in membrane trafficking; Peterman et al, 2004), were additionally identified as NF-induced genes. Arabidopsis (Arabidopsis thaliana) PATELLIN1 is thought to bind phosphatidylinositol and its phosphorylated derivatives, themselves known to regulate membrane trafficking (Peterman et al, 2004).…”