{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,27]],"date-time":"2026-10-27T00:13:39Z","timestamp":1793060019086,"version":"4.5.0"},"reference-count":37,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2022,3,1]],"date-time":"2022-03-01T00:00:00Z","timestamp":1646092800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R01AI139242, R21AI148999"],"award-info":[{"award-number":["R01AI139242, R21AI148999"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"<jats:p>The intracellular pathogen <jats:italic>Chlamydia trachomatis<\/jats:italic> secretes multiple early effectors into the host cell to promote invasion. A key early effector during host cell entry, Tarp (translocated actin-recruiting phosphoprotein) is comprised of multiple protein domains known to have roles in cell signaling, G-actin nucleation and F-actin bundle formation. <jats:italic>In vitro<\/jats:italic>, the actin bundles generated by Tarp are uncharacteristically flexible, however, <jats:italic>in vivo<\/jats:italic>, the biological significance of Tarp-mediated actin bundles remains unknown. We hypothesize that Tarp\u2019s ability to generate unique actin bundles, in part, facilitates chlamydial entry into epithelial cells. To study the <jats:italic>in vivo<\/jats:italic> interaction between Tarp and F-actin, we transgenically expressed Tarp in <jats:italic>Drosophila melanogaster<\/jats:italic> tissues. Tarp expressed in <jats:italic>Drosophila<\/jats:italic> is phosphorylated and forms F-actin-enriched aggregates in tissues. To gain insight into the significance of Tarp actin bundles <jats:italic>in vivo<\/jats:italic>, we utilized the well-characterized model system of mechanosensory bristle development in <jats:italic>Drosophila melanogaster<\/jats:italic>. Tarp expression in wild type flies produced curved bristles, indicating a perturbation in F-actin dynamics during bristle development. Two F-actin bundlers, Singed\/Fascin and Forked\/Espin, are important for normal bristle shape. Surprisingly, Tarp expression in the bristles displaced Singed\/Fascin away from F-actin bundles. Tarp\u2019s competitive behavior against Fascin during F-actin bundling was confirmed <jats:italic>in vitro<\/jats:italic>. Loss of either <jats:italic>singed<\/jats:italic> or <jats:italic>forked<\/jats:italic> in flies leads to highly deformed bristles. Strikingly, Tarp partially rescued the loss of <jats:italic>singed<\/jats:italic>, reducing the severity of the bristle morphology defect. This work provides <jats:italic>in vivo<\/jats:italic> confirmation of Tarp\u2019s F-actin bundling activity and further uncovers a competitive behavior against the host bundler Singed\/Fascin during bundle assembly. Also, we demonstrate the utility of <jats:italic>Drosophila melanogaster<\/jats:italic> as an <jats:italic>in vivo<\/jats:italic> cell biological platform to study bacterial effector function.<\/jats:p>","DOI":"10.3389\/fcimb.2022.811407","type":"journal-article","created":{"date-parts":[[2022,3,1]],"date-time":"2022-03-01T05:43:48Z","timestamp":1646113428000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":4,"title":["The Chlamydia trachomatis Early Effector Tarp Outcompetes Fascin in Forming F-Actin Bundles In Vivo"],"prefix":"10.3389","volume":"12","author":[{"given":"George F.","family":"Aranjuez","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jongeon","family":"Kim","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Travis J.","family":"Jewett","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2022,3,1]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"81","DOI":"10.1016\/j.mib.2008.11.009","article-title":"Effector Protein Modulation of Host Cells: Examples in the Chlamydia Spp. Arsenal","volume":"12","author":"Betts","year":"2009","journal-title":"Curr. 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