title: Cooperation between actin-binding proteins of invasive Salmonella: SipA potentiates SipC nucleation and bundling of actin.
abstract: Pathogen-induced remodelling of the host cell actin cytoskeleton drives internalization of invasive Salmonella by non-phagocytic intestinal epithelial cells. Two Salmonella actin-binding proteins are involved in internalization: SipC is essential for the process, while SipA enhances its efficiency. Using purified SipC and SipA proteins in in vitro assays of actin dynamics and F-actin bundling, we demonstrate that SipA stimulates substantially SipC-mediated nucleation of actin polymerization. SipA additionally enhances SipC-mediated F-actin bundling, and SipC-SipA collaboration generates stable networks of F-actin bundles. The data show that bacterial SipC and SipA cooperate to direct efficient modulation of actin dynamics, independently of host cell proteins. The ability of SipA to enhance SipC-induced reorganization of the actin cytoskeleton in vivo was confirmed using semi-permeabilized cultured mammalian cells.
authors.affiliation: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
authors.forename: E J
authors.initials: EJ
authors.lastname: McGhie
authors.forename: R D
authors.initials: RD
authors.lastname: Hayward
authors.forename: V
authors.initials: V
authors.lastname: Koronakis
mesh_terms: D000199:Actins / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D002460:Cell Line; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D006790:Host-Parasite Interactions / Q000502:physiology*; D006801:Humans; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D012475:Salmonella / Q000378:metabolism*
chemical_list: D000199:Actins; D001426:Bacterial Proteins; D008840:Microfilament Proteins; C094578:Salmonella invasion protein C; C118287:SipA protein, Salmonella