Shiga toxin induces tubular membrane invaginations for its uptake into cells.
Clathrin seems to be dispensable for some endocytic processes and, in several instances, no cytosolic coat protein complexes could be detected at sites of membrane invagination. Hence, new principles must in these cases be invoked to account for the mechanical force driving membrane shape changes. Here we show that the Gb3 (glycolipid)-binding B-subunit of bacterial Shiga toxin induces narrow tubular membrane invaginations in human and mouse cells and model membranes. In cells, tubule occurrence increases on energy depletion and inhibition of dynamin or actin functions. Our data thus demonstrate that active cellular processes are needed for tubule scission rather than tubule formation. We conclude that the B-subunit induces lipid reorganization that favours negative membrane curvature, which drives the formation of inward membrane tubules. Our findings support a model in which the lateral growth of B-subunit-Gb3 microdomains is limited by the invagination process, which itself is regulated by membrane tension. The physical principles underlying this basic cargo-induced membrane uptake may also be relevant to other internalization processes, creating a rationale for conceptualizing the perplexing diversity of endocytic routes.
Institut Curie, Centre de Recherche, Laboratoire Trafic, Signalisation et Ciblage Intracellulaires, Paris Cedex 05, France.
Winfried
W
Römer
Ludwig
L
Berland
Valérie
V
Chambon
Katharina
K
Gaus
Barbara
B
Windschiegl
Danièle
D
Tenza
Mohamed R E
MR
Aly
Vincent
V
Fraisier
Jean-Claude
JC
Florent
David
D
Perrais
Christophe
C
Lamaze
Graça
G
Raposo
Claudia
C
Steinem
Pierre
P
Sens
Patricia
P
Bassereau
Ludger
L
Johannes
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects*; D011992:Endosomes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D021381:Protein Transport / Q000187:drug effects; D022621:Shiga Toxin / Q000378:metabolism* / Q000494:pharmacology*; D012762:Shigella dysenteriae
D008081:Liposomes; D022621:Shiga Toxin