title: Annexin 2 is a phosphatidylinositol (4,5)-bisphosphate binding protein recruited to actin assembly sites at cellular membranes.
abstract: Annexin 2 is a Ca(2+)-regulated membrane protein and an F-actin-binding protein enriched at actin assembly sites both, on the plasma membrane and on endosomal vesicles. Here, we identify annexin 2 as a phosphatidylinositol (4,5)-bisphosphate (PtdIns(4,5)P(2))-interacting protein, thereby explaining this specific membrane association. Using the pleckstrin-homology (PH) domain of phospholipase Cdelta1 fused to yellow fluorescent protein as a marker for PtdIns(4,5)P(2), we show that annexin 2 and its ligand p11 (S100A10) are targeted to sites of PtdIns(4,5)P(2) enrichment where F-actin accumulates. At the plasma membrane, adhesion of pedestal-forming enteropathogenic Escherichia coli induces a recruitment of 1-phosphatidylinositol-4-phosphate 5-kinase (PtdIns4P 5-kinase) and an enrichment of PtdIns(4,5)P(2) and annexin 2-p11 at sites of bacterial adhesion. Induction of PtdIns(4,5)P(2)-enriched ruffles and PtdIns(4,5)P(2)-positive, actin-coated vacuoles by Arf6-mediated activation of PtdIns4P 5-kinase also leads to a concomitant accumulation of the annexin 2-p11 complex and the PH domain. Binding studies with immobilized phosphoinositides and phosphoinositide-containing liposomes reveal that the purified annexin 2-p11 complex directly and specifically binds to PtdIns(4,5)P(2) with an affinity comparable to that of the PH domain of phospholipase Cdelta1. Experiments using individual subunits identify annexin 2 as the PtdIns(4,5)P(2)-binding entity. Thus, the direct interaction of annexin 2 with PtdIns(4,5)P(2) is a means of specifically recruiting the annexin 2-p11 complex to sites of membrane-associated actin assembly.
authors.affiliation: Institute for Medical Biochemistry, Center for Molecular Biology of Inflammation, von Esmarch-Str. 56, Münster 48149, Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Rescher
authors.forename: Daniela
authors.initials: D
authors.lastname: Ruhe
authors.forename: Carsten
authors.initials: C
authors.lastname: Ludwig
authors.forename: Nicole
authors.initials: N
authors.lastname: Zobiack
authors.forename: Volker
authors.initials: V
authors.lastname: Gerke
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D017306:Annexin A2 / Q000378:metabolism*; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D000089982:ADP-Ribosylation Factor 6; D000199:Actins; D017306:Annexin A2; D017931:DNA Primers; D019269:Phosphatidylinositol 4,5-Diphosphate; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human