title: The conserved Tarp actin binding domain is important for chlamydial invasion.
abstract: The translocated actin recruiting phosphoprotein (Tarp) is conserved among all pathogenic chlamydial species. Previous reports identified single C. trachomatis Tarp actin binding and proline rich domains required for Tarp mediated actin nucleation. A peptide antiserum specific for the Tarp actin binding domain was generated and inhibited actin polymerization in vitro and C. trachomatis entry in vivo, indicating an essential role for Tarp in chlamydial pathogenesis. Sequence analysis of Tarp orthologs from additional chlamydial species and C. trachomatis serovars indicated multiple putative actin binding sites. In order to determine whether the identified actin binding domains are functionally conserved, GST-Tarp fusions from multiple chlamydial species were examined for their ability to bind and nucleate actin. Chlamydial Tarps harbored variable numbers of actin binding sites and promoted actin nucleation as determined by in vitro polymerization assays. Our findings indicate that Tarp mediated actin binding and nucleation is a conserved feature among diverse chlamydial species and this function plays a critical role in bacterial invasion of 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, Montana, United States of America.
authors.forename: Travis J
authors.initials: TJ
authors.lastname: Jewett
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Miller
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Dooley
authors.forename: Ted
authors.initials: T
authors.lastname: Hackstadt
mesh_terms: D000199:Actins / Q000037:antagonists & inhibitors*; D001426:Bacterial Proteins / Q000502:physiology; D001665:Binding Sites; D002689:Chlamydia / Q000472:pathogenicity*; D002690:Chlamydia Infections / Q000209:etiology; D006367:HeLa Cells / Q000382:microbiology; D006801:Humans; D011485:Protein Binding; D014774:Virulence; D053586:Virus Internalization
chemical_list: D000199:Actins; D001426:Bacterial Proteins