title: Anthrax toxin triggers endocytosis of its receptor via a lipid raft-mediated clathrin-dependent process.
abstract: The protective antigen (PA) of the anthrax toxin binds to a cell surface receptor and thereby allows lethal factor (LF) to be taken up and exert its toxic effect in the cytoplasm. Here, we report that clustering of the anthrax toxin receptor (ATR) with heptameric PA or with an antibody sandwich causes its association to specialized cholesterol and glycosphingolipid-rich microdomains of the plasma membrane (lipid rafts). We find that although endocytosis of ATR is slow, clustering it into rafts either via PA heptamerization or using an antibody sandwich is necessary and sufficient to trigger efficient internalization and allow delivery of LF to the cytoplasm. Importantly, altering raft integrity using drugs prevented LF delivery and cleavage of cytosolic MAPK kinases, suggesting that lipid rafts could be therapeutic targets for drugs against anthrax. Moreover, we show that internalization of PA is dynamin and Eps15 dependent, indicating that the clathrin-dependent pathway is the major route of anthrax toxin entry into the cell. The present work illustrates that although the physiological role of the ATR is unknown, its trafficking properties, i.e., slow endocytosis as a monomer and rapid clathrin-mediated uptake on clustering, make it an ideal anthrax toxin receptor.
authors.affiliation: Department of Genetics and Microbiology, University of Geneva, 1211 Geneva 4, Switzerland.
authors.forename: Laurence
authors.initials: L
authors.lastname: Abrami
authors.forename: Shihui
authors.initials: S
authors.lastname: Liu
authors.forename: Pierre
authors.initials: P
authors.lastname: Cosson
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Leppla
authors.forename: F Gisou
authors.initials: FG
authors.lastname: van der Goot
mesh_terms: D000818:Animals; D000881:Anthrax / Q000378:metabolism* / Q000503:physiopathology; D000906:Antibodies; D000942:Antigens, Bacterial; D001427:Bacterial Toxins / Q000378:metabolism*; D016466:CHO Cells; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism*; D006224:Cricetinae; D034281:Dynamins / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D005057:Eukaryotic Cells / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology*; D048369:MAP Kinase Kinase 1; D046911:Macromolecular Substances; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism; D018000:Receptors, Peptide / Q000187:drug effects / Q000378:metabolism*; D022161:Transport Vesicles / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D000906:Antibodies; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D051242:Caveolin 1; D022461:Caveolins; D002966:Clathrin; D046911:Macromolecular Substances; D010750:Phosphoproteins; D018000:Receptors, Peptide; C030325:anthrax toxin; C070309:anthrax toxin receptors; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D034281:Dynamins