title: High affinity RGD-binding sites at the plasma membrane of Arabidopsis thaliana links the cell wall.
abstract: The heptapeptide Tyr-Gly-Arg-Gly-Asp-Ser-Pro containing the sequence Arg-Gly-Asp (RGD--the essential structure recognised by animal cells in substrate adhesion molecules) was tested on epidermal cells of onion and cultured cells of Arabidopsis upon plasmolysis. Dramatic changes were observed on both types of cells following treatment: on onion cells, Hechtian strands linking the cell wall to the membrane were lost, while Arabidopsis cells changed from concave to convex plasmolysis. A control heptapeptide Tyr-Gly-Asp-Gly-Arg-Ser-Pro had no effect on the shape of plasmolysed cells. Protoplasts isolated from Arabidopsis cells agglutinate in the presence of ProNectinF, a genetically engineered protein of 72 kDa containing 13 RGD sequences: several protoplasts may adhere to a single molecule of ProNectinF. The addition of the RGD-heptapeptide disrupted the adhesion between the protoplasts. Purified plasma membrane from Arabidopsis cells exhibits specific binding sites for the iodinated RGD-heptapeptide. The binding is saturable, reversible, and two types of high affinity sites (Kd1 approximately 1 nM, and Kd2 approximately 40 nM) can be discerned. Competitive inhibition by several structurally related peptides and proteins noted the specific requirement for the RGD sequence. Thus, the RGD-binding activity of Arabidopsis fulfils the adhesion features of integrins, i.e. peptide specificity, subcellular location, and involvement in plasma membrane-cell wall attachments.
authors.affiliation: Signaux et Messages Cellulaires chez les Végétaux, UMR 5546 CNRS, Université Paul Sabatier, Toulouse, France. canuth@cict.fr
authors.forename: H
authors.initials: H
authors.lastname: Canut
authors.forename: A
authors.initials: A
authors.lastname: Carrasco
authors.forename: J P
authors.initials: JP
authors.lastname: Galaud
authors.forename: C
authors.initials: C
authors.lastname: Cassan
authors.forename: H
authors.initials: H
authors.lastname: Bouyssou
authors.forename: N
authors.initials: N
authors.lastname: Vita
authors.forename: P
authors.initials: P
authors.lastname: Ferrara
authors.forename: R
authors.initials: R
authors.lastname: Pont-Lezica
mesh_terms: D017360:Arabidopsis / Q000378:metabolism* / Q000648:ultrastructure; D001665:Binding Sites; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D007700:Kinetics; D009842:Oligopeptides / Q000378:metabolism*; D019697:Onions; D010940:Plant Proteins / Q000378:metabolism*
chemical_list: D009842:Oligopeptides; D010940:Plant Proteins; C047981:arginyl-glycyl-aspartic acid