title: 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 beta-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 beta-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. beta-Yariv treatment resulted in terminal cell bulging, puncta formation, and depolymerization/disorganization of MTs, indicating a likely role for AGPs in cortical MT organization. beta-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.
authors.affiliation: Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701-2979, USA.
authors.forename: Harjinder Singh
authors.initials: HS
authors.lastname: Sardar
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.forename: Allan M
authors.initials: AM
authors.lastname: Showalter
mesh_terms: D000199:Actins / Q000378:metabolism* / Q000648:ultrastructure; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D015638:Cytochalasin D / Q000494:pharmacology; D005960:Glucosides / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000032:analysis; D018551:Solanum lycopersicum / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D009088:Mucoproteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D009578:Nitrobenzenes / Q000494:pharmacology; D009946:Organothiophosphorus Compounds / Q000494:pharmacology; D010696:Phloroglucinol / Q000031:analogs & derivatives / Q000494:pharmacology; D010940:Plant Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis; D014026:Nicotiana / Q000166:cytology / Q000235:genetics*; D050257:Tubulin Modulators / Q000494:pharmacology
chemical_list: D000199:Actins; D005960:Glucosides; D009088:Mucoproteins; D009578:Nitrobenzenes; D009946:Organothiophosphorus Compounds; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D050257:Tubulin Modulators; C104977:Yariv reagent; C006619:arabinogalactan proteins; D049452:Green Fluorescent Proteins; D015638:Cytochalasin D; C017823:amiprophos methyl; D010696:Phloroglucinol