title: Reorganization of the endosomal system in Salmonella-infected cells: the ultrastructure of Salmonella-induced tubular compartments.
abstract: During the intracellular life of Salmonella enterica, a unique membrane-bound compartment termed Salmonella-containing vacuole, or SCV, is formed. By means of translocated effector proteins, intracellular Salmonella also induce the formation of extensive, highly dynamic membrane tubules termed Salmonella-induced filaments or SIF. Here we report the first detailed ultrastructural analyses of the SCV and SIF by electron microscopy (EM), EM tomography and live cell correlative light and electron microscopy (CLEM). We found that a subset of SIF is composed of double membranes that enclose portions of host cell cytosol and cytoskeletal filaments within its inner lumen. Despite some morphological similarities, we found that the formation of SIF double membranes is independent from autophagy and requires the function of the effector proteins SseF and SseG. The lumen of SIF network is accessible to various types of endocytosed material and our CLEM analysis of double membrane SIF demonstrated that fluid phase markers accumulate only between the inner and outer membrane of these structures, a space continual with endosomal lumen. Our work reveals how manipulation of the endosomal membrane system by an intracellular pathogen results in a unique tubular membrane compartmentalization of the host cell, generating a shielded niche permissive for intracellular proliferation of Salmonella.
authors.affiliation: Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
authors.forename: Viktoria
authors.initials: V
authors.lastname: Krieger
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory Heidelberg, Heidelberg, Germany; Mikrobiologisches Institut, Universitätsklinikum Erlangen, Erlangen, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Liebl
authors.affiliation: Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
authors.forename: Yuying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Mikrobiologisches Institut, Universitätsklinikum Erlangen, Erlangen, Germany.
authors.forename: Roopa
authors.initials: R
authors.lastname: Rajashekar
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory Heidelberg, Heidelberg, Germany.
authors.forename: Petr
authors.initials: P
authors.lastname: Chlanda
authors.affiliation: Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Giesker
authors.affiliation: Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany; Mikrobiologisches Institut, Universitätsklinikum Erlangen, Erlangen, Germany.
authors.forename: Deepak
authors.initials: D
authors.lastname: Chikkaballi
authors.affiliation: Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany; Mikrobiologisches Institut, Universitätsklinikum Erlangen, Erlangen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hensel
mesh_terms: D000818:Animals; D001343:Autophagy; D001426:Bacterial Proteins / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D008264:Macrophages / Q000382:microbiology / Q000473:pathology*; D051379:Mice; D046529:Microscopy, Electron, Transmission; D010587:Phagocytosis / Q000502:physiology; D021381:Protein Transport; D012475:Salmonella / Q000502:physiology*; D012480:Salmonella Infections / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D014617:Vacuoles / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins