title: Three-dimensional architecture of actin filaments in Listeria monocytogenes comet tails.
abstract: The intracellular bacterial pathogen Listeria monocytogenes is capable of remodelling the actin cytoskeleton of its host cells such that "comet tails" are assembled powering its movement within cells and enabling cell-to-cell spread. We used cryo-electron tomography to visualize the 3D structure of the comet tails in situ at the level of individual filaments. We have performed a quantitative analysis of their supramolecular architecture revealing the existence of bundles of nearly parallel hexagonally packed filaments with spacings of 12-13 nm. Similar configurations were observed in stress fibers and filopodia, suggesting that nanoscopic bundles are a generic feature of actin filament assemblies involved in motility; presumably, they provide the necessary stiffness. We propose a mechanism for the initiation of comet tail assembly and two scenarios that occur either independently or in concert for the ensuing actin-based motility, both emphasizing the role of filament bundling.
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Jasnin
authors.forename: Shoh
authors.initials: S
authors.lastname: Asano
authors.forename: Edith
authors.initials: E
authors.lastname: Gouin
authors.forename: Reiner
authors.initials: R
authors.lastname: Hegerl
authors.forename: Jürgen M
authors.initials: JM
authors.lastname: Plitzko
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Villa
authors.forename: Pascale
authors.initials: P
authors.lastname: Cossart
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumeister
mesh_terms: D002460:Cell Line; D020285:Cryoelectron Microscopy / Q000379:methods; D006801:Humans; D008089:Listeria monocytogenes / Q000378:metabolism / Q000648:ultrastructure*; D008088:Listeriosis; D008958:Models, Molecular; D022502:Stress Fibers / Q000378:metabolism / Q000648:ultrastructure*
keywords: actin bundles; bundling proteins; cellular actin structures; force generation