title: Identification of a bacterial factor required for actin-based motility of Burkholderia pseudomallei.
abstract: Burkholderia pseudomallei is a Gram-negative facultative intracellular pathogen that enters and escapes from eukaryotic cells using the power of actin polymerization. We have identified a bacterial protein (BimA) that is required for the ability of B. pseudomallei to induce the formation of actin tails. BimA contains proline-rich motifs and WH2-like domains and shares limited homology at the C-terminus with the Yersinia autosecreted adhesin YadA. BimA is located at the pole of the bacterial cell at which actin polymerization occurs and mutation of bimA abolished actin-based motility of the pathogen in J774.2 cells. Transient expression of BimA in HeLa cells resulted in F-actin clustering reminiscent of that seen on WASP overexpression. Antibody-mediated clustering of a CD32 chimera in which the cytoplasmic domain was replaced with BimA resulted in localization of the chimera to the tips of F-actin enriched membrane protrusions. We report that purified truncated BimA protein binds monomeric actin in a concentration-dependent manner in cosedimentation assays and that BimA stimulates actin polymerization in vitro in a manner independent of the cellular Arp2/3 complex.
authors.affiliation: Division of Microbiology, Institute for Animal Health, Compton Laboratory, Berkshire, RG20 7NN, UK.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Stevens
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Stevens
authors.forename: Robert L
authors.initials: RL
authors.lastname: Jeng
authors.forename: Lowrie A
authors.initials: LA
authors.lastname: Taylor
authors.forename: Michael W
authors.initials: MW
authors.lastname: Wood
authors.forename: Pippa
authors.initials: P
authors.lastname: Hawes
authors.forename: Paul
authors.initials: P
authors.lastname: Monaghan
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Welch
authors.forename: Edouard E
authors.initials: EE
authors.lastname: Galyov
mesh_terms: D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016957:Burkholderia pseudomallei / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D015964:Gene Expression Regulation, Bacterial; D006367:HeLa Cells; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009068:Movement; D009154:Mutation; D011392:Proline
chemical_list: D000199:Actins; D001426:Bacterial Proteins; C503173:BimA protein, Burkholderia pseudomallei; D008840:Microfilament Proteins; D011392:Proline