title: Role of the WASP family proteins for Mycobacterium marinum actin tail formation.
abstract: Mycobacterium marinum, a natural pathogen of fish and frogs and an occasional pathogen of humans, is capable of inducing actin tail formation within the cytoplasm of macrophages, leading to actin-based motility and intercellular spread. Actin tail formation by M. marinum is markedly reduced in macrophages deficient in the Wiskott-Aldrich syndrome protein (WASP), which still contain the closely related and ubiquitously expressed protein N-WASP (neuronal WASP). In fibroblasts lacking both WASP and N-WASP, M. marinum is incapable of efficient actin polymerization and of intercellular spread. By reconstituting these cells, we find that M. marinum is able to use either WASP or N-WASP to induce actin polymerization. Inhibition or genetic deletion of tyrosine phosphorylation, Nck, WASP-interacting protein, and Cdc42 does not affect M. marinum actin tail formation, excluding the participation of these molecules as upstream activators of N-WASP in the initiation of actin-based motility. In contrast, deletion of the phosphatidylinositol 4,5-bisphosphate-binding basic motif in N-WASP eliminates M. marinum actin tail formation. Together, these data demonstrate that M. marinum subversion of host actin polymerization is most similar to distantly related Gram-negative organisms but that its mechanism for activating WASP family proteins is unique.
authors.affiliation: Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, CA 94143, USA.
authors.forename: Luisa M
authors.initials: LM
authors.lastname: Stamm
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Pak
authors.forename: J Hiroshi
authors.initials: JH
authors.lastname: Morisaki
authors.forename: Scott B
authors.initials: SB
authors.lastname: Snapper
authors.forename: Klemens
authors.initials: K
authors.lastname: Rottner
authors.forename: Silvia
authors.initials: S
authors.lastname: Lommel
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Brown
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D001704:Biopolymers; D019084:Fluorescent Antibody Technique, Indirect; D049452:Green Fluorescent Proteins; D008264:Macrophages / Q000378:metabolism* / Q000382:microbiology; D051379:Mice; D018345:Mice, Knockout; D019910:Mycobacterium marinum / Q000502:physiology*; D017434:Protein Structure, Tertiary; D051300:Wiskott-Aldrich Syndrome Protein Family / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D001704:Biopolymers; D051300:Wiskott-Aldrich Syndrome Protein Family; D049452:Green Fluorescent Proteins