title: Cell geometry guides the dynamic targeting of apoplastic GPI-linked lipid transfer protein to cell wall elements and cell borders in Arabidopsis thaliana.
abstract: During cellular morphogenesis, changes in cell shape and cell junction topology are fundamental to normal tissue and organ development. Here we show that apoplastic Glycophosphatidylinositol (GPI)-anchored Lipid Transfer Protein (LTPG) is excluded from cell junctions and flat wall regions, and passively accumulates around their borders in the epidermal cells of Arabidopsis thaliana. Beginning with intense accumulation beneath highly curved cell junction borders, this enrichment is gradually lost as cells become more bulbous during their differentiation. In fully mature epidermal cells, YFP-LTPG often shows a fibrous cellulose microfibril-like pattern within the bulging outer faces. Physical contact between a flat glass surface and bulbous cell surface induces rapid and reversible evacuation from contact sites and accumulation to the curved wall regions surrounding the contact borders. Thus, LTPG distribution is dynamic, responding to changes in cell shape and wall curvature during cell growth and differentiation. We hypothesize that this geometry-based mechanism guides wax-carrying LTPG to functional sites, where it may act to "seal" the vulnerable border surrounding cell-cell junctions and assist in cell wall fortification and cuticular wax deposition.
authors.affiliation: Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Chris
authors.initials: C
authors.lastname: Ambrose
authors.forename: Allan
authors.initials: A
authors.lastname: DeBono
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Wasteneys
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation; D002473:Cell Wall / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D050556:Fatty Acid-Binding Proteins; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D009024:Morphogenesis; D019441:Plant Epidermis / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D014885:Waxes / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D050556:Fatty Acid-Binding Proteins; C542162:Ltpg1 protein, Arabidopsis; D008164:Luminescent Proteins; D020033:Protein Isoforms; D014885:Waxes; C054562:yellow fluorescent protein, Bacteria