title: Tobacco WLIM1 is a novel F-actin binding protein involved in actin cytoskeleton remodeling.
abstract: We used confocal microscopy and in vitro analyses to show that Nicotiana tabacum WLIM1, a LIM domain protein related to animal Cys-rich proteins, is a novel actin binding protein in plants. Green fluorescent protein (GFP)-tagged WLIM1 protein accumulated in the nucleus and cytoplasm of tobacco BY2 cells. It associated predominantly with actin cytoskeleton, as demonstrated by colabeling and treatment with actin-depolymerizing latrunculin B. High-speed cosedimentation assays revealed the ability of WLIM1 to bind directly to actin filaments with high affinity. Fluorescence recovery after photobleaching and fluorescence loss in photobleaching showed a highly dynamic in vivo interaction of WLIM1-GFP with actin filaments. Expression of WLIM1-GFP in BY2 cells significantly delayed depolymerization of the actin cytoskeleton induced by latrunculin B treatment. WLIM1 also stabilized actin filaments in vitro. Importantly, expression of WLIM1-GFP in Nicotiana benthamiana leaves induces significant changes in actin cytoskeleton organization, specifically, fewer and thicker actin bundles than in control cells, suggesting that WLIM1 functions as an actin bundling protein. This hypothesis was confirmed by low-speed cosedimentation assays and direct observation of F-actin bundles that formed in vitro in the presence of WLIM1. Taken together, these data identify WLIM1 as a novel actin binding protein that increases actin cytoskeleton stability by promoting bundling of actin filaments.
authors.affiliation: Centre de Recherche Public-Santé, L-1526 Luxembourg.
authors.forename: Clément
authors.initials: C
authors.lastname: Thomas
authors.forename: Céline
authors.initials: C
authors.lastname: Hoffmann
authors.forename: Monika
authors.initials: M
authors.lastname: Dieterle
authors.forename: Marleen
authors.initials: M
authors.lastname: Van Troys
authors.forename: Christophe
authors.initials: C
authors.lastname: Ampe
authors.forename: André
authors.initials: A
authors.lastname: Steinmetz
mesh_terms: D008841:Actin Cytoskeleton / Q000648:ultrastructure*; D000199:Actins / Q000037:antagonists & inhibitors / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002478:Cells, Cultured; D004136:Dinitrobenzenes / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000032:analysis; D008840:Microfilament Proteins / Q000737:chemistry / Q000502:physiology*; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000032:analysis; D013424:Sulfanilamides / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D050257:Tubulin Modulators / Q000494:pharmacology
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004136:Dinitrobenzenes; D008840:Microfilament Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D013424:Sulfanilamides; D013844:Thiazoles; D053778:Thiazolidines; D050257:Tubulin Modulators; D049452:Green Fluorescent Proteins; C012465:oryzalin; C037068:latrunculin B