Molecular Interactions of Arabinogalactan Proteins with Cortical Microtubules and F-Actin in Bright Yellow-2 Tobacco Cultured Cells

Abstract

Arabinogalactan proteins (AGPs), a superfamily of plant hydroxyproline-rich glycoproteins, are present at cell surfaces. Although precise functions of AGPs remain elusive, they are widely implicated in plant growth and development. A well-characterized classical tomato (Lycopersicon esculentum) AGP containing a glycosylphosphatidylinositol plasma membrane anchor sequence was used here to elucidate functional roles of AGPs. Transgenic tobacco (Nicotiana tabacum) Bright Yellow-2 (BY-2) cells stably expressing green fluorescent protein (GFP)-LeAGP-1 were plasmolysed and used to localize LeAGP-1 on the plasma membrane and in Hechtian strands. Cytoskeleton disruptors and b-Yariv reagent (which binds and perturbs AGPs) were used to examine the role of LeAGP-1 as a candidate linker protein between the plasma membrane and cytoskeleton. This study used a two-pronged approach. First, BY-2 cells, either wild type or expressing GFP-microtubule (MT)-binding domain, were treated with b-Yariv reagent, and effects on MTs and F-actin were observed. Second, BY-2 cells expressing GFP-LeAGP-1 were treated with amiprophosmethyl and cytochalasin-D to disrupt MTs and F-actin, and effects on LeAGP-1 localization were observed. b-Yariv treatment resulted in terminal cell bulging, puncta formation, and depolymerization/disorganization of MTs, indicating a likely role for AGPs in cortical MT organization. b-Yariv treatment also resulted in the formation of thicker actin filaments, indicating a role for AGPs in actin polymerization. Similarly, amiprophosmethyl and cytochalasin-D treatments resulted in relocalization of LeAGP-1 on Hechtian strands and indicate roles for MTs and F-actin in AGP organization at the cell surface and in Hechtian strands. Collectively, these studies indicate that glycosylphosphatidylinositol-anchored AGPs function to link the plasma membrane to the cytoskeleton.

The Organization Pattern of Root Border-Like Cells of Arabidopsis Is Dependent on Cell Wall Homogalacturonan

“…Arabinogalactan-proteins are highly glycosylated members of the Hyp-rich glycoprotein superfamily. Many of these glycoproteins, the so-called classical arabinogalactan-proteins, are anchored to the plasma membrane by a glycosylphosphatidylinositol anchor and have the potential to bind both cell wall components (Immerzeel et al, 2006) and cytosolic cortical microtubules (Schultz et al, 2002;Sardar et al, 2006;Nguema-Ona et al, 2007). These proteoglycans have been implicated in many aspects of plant life, including cell expansion, cell signaling and communication, embryogenesis, and wound response (Johnson et al, 2003;Seifert and Roberts, 2007;Driouich and Baskin, 2008).…”

Nanospherical arabinogalactan proteins are a key component of the high-strength adhesive secreted by English ivy

“…To test whether AGPs are contained in the ivy nanoparticles, Yariv phenylglycoside dye, a reagent also called β-glucosyl Yariv (β-GlcY), which selectively binds to the AGPs via recognizing both given protein moieties and β-1,3-galactan chains with greater than five residues (24,30,(32)(33)(34)(35), was applied for identification. As shown in Fig.…”

Root exudate ofSolanum tuberosumis enriched in galactose-containing molecules and impacts the growth ofPectobacterium atrosepticum

“…To check whether AGPs present in root exudates could affect bacterial growth, exudates were incubated overnight with 5 mg mL À1 b-D-glucosyl Yariv reagent and added to the growth medium. The b-D-glucosyl Yariv reagent binds and precipitates AGPs, thus interfering with their function (Yariv et al, 1967;Sardar et al, 2006;Kitazawa et al, 2013;Marzec et al, 2015). When exudate treated with b-D-glucosyl Yariv reagent was added to the growth medium, biomass production of P. atrosepticum was only slightly reduced.…”