title: Chlamydial TARP is a bacterial nucleator of actin.
abstract: Chlamydia trachomatis entry into host cells results from a parasite-directed remodeling of the actin cytoskeleton. A type III secreted effector, TARP (translocated actin recruiting phosphoprotein), has been implicated in the recruitment of actin to the site of internalization. To elucidate the role of TARP in actin recruitment, we identified host cell proteins that associated with recombinant GST-TARP fusions. TARP directly associated with actin, and this interaction promoted actin nucleation as determined by in vitro polymerization assays. Domain analysis of TARP identified an actin-binding domain that bears structural and primary amino acid sequence similarity to WH2 domain family proteins. In addition, a proline-rich domain was found to promote TARP oligomerization and was required for TARP-dependent nucleation of new actin filaments. Our findings reveal a mechanism by which chlamydiae induce localized cytoskeletal changes by the translocated effector TARP during entry into host cells.
authors.affiliation: Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
authors.forename: Travis J
authors.initials: TJ
authors.lastname: Jewett
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Fischer
authors.forename: David J
authors.initials: DJ
authors.lastname: Mead
authors.forename: Ted
authors.initials: T
authors.lastname: Hackstadt
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism; D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002692:Chlamydia trachomatis / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D001426:Bacterial Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins