title: Rck of Salmonella enterica, subspecies enterica serovar enteritidis, mediates zipper-like internalization.
abstract: Salmonella can invade non-phagocytic cells through its type III secretion system (T3SS-1), which induces a Trigger entry process. This study showed that Salmonella enterica, subspecies enterica serovar Enteritidis can also invade cells via the Rck outer membrane protein. Rck was necessary and sufficient to enable non-invasive E. coli and Rck-coated beads to adhere to and invade different cells. Internalization analysis of latex beads coated with different Rck peptides showed that the peptide containing amino acids 140-150 promoted adhesion, whereas amino acids between 150 and 159 modulated invasion. Expression of dominant-negative derivatives and use of specific inhibitors demonstrated the crucial role of small GTPases Rac1 and Cdc42 in activating the Arp2/3 complex to trigger formation of actin-rich accumulation, leading to Rck-dependent internalization. Finally, scanning and transmission electron microscopy with Rck-coated beads and E. coli expressing Rck revealed microvillus-like extensions that formed a Zipper-like structure, engulfing the adherent beads and bacteria. Overall, our results provide new insights into the Salmonella T3SS-independent invasion mechanisms and strongly suggest that Rck induces a Zipper-like entry mechanism. Consequently, Salmonella seems to be the first bacterium found to be able to induce both Zipper and Trigger mechanisms to invade host cells.
authors.affiliation: INRA, UR1282 Infectiologie Animale et Santé Publique, Nouzilly, France.
authors.forename: Manon
authors.initials: M
authors.lastname: Rosselin
authors.forename: Isabelle
authors.initials: I
authors.lastname: Virlogeux-Payant
authors.forename: Christian
authors.initials: C
authors.lastname: Roy
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bottreau
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Sizaret
authors.forename: Lily
authors.initials: L
authors.lastname: Mijouin
authors.forename: Pierre
authors.initials: P
authors.lastname: Germon
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Caron
authors.forename: Philippe
authors.initials: P
authors.lastname: Velge
authors.forename: Agnès
authors.initials: A
authors.lastname: Wiedemann
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D004705:Endocytosis / Q000502:physiology*; D051379:Mice; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D041681:NIH 3T3 Cells; D012481:Salmonella Infections, Animal / Q000378:metabolism* / Q000382:microbiology* / Q000473:pathology; D012477:Salmonella enteritidis / Q000737:chemistry / Q000472:pathogenicity* / Q000502:physiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D020559:Monomeric GTP-Binding Proteins