Biophysical Characterization Of Actin Bundles Generated By The Chlamydia Trachomatis Tarp Effector

Keywords

Actin bundles; Bending persistence length; Chlamydia trachomatis; Cytoskeleton; Effector; Tarp

Abstract

Chlamydia trachomatis entry into host cells is mediated by pathogen-directed remodeling of the actin cytoskeleton. The chlamydial type III secreted effector, translocated actin recruiting phosphoprotein (Tarp), has been implicated in the recruitment of actin to the site of internalization. Tarp harbors G-actin binding and proline rich domains required for Tarp-mediated actin nucleation as well as unique F-actin binding domains implicated in the formation of actin bundles. Little is known about the mechanical properties of actin bundles generated by Tarp or the mechanism by which Tarp mediates actin bundle formation. In order to characterize the actin bundles and elucidate the role of different Tarp domains in the bundling process, purified Tarp effectors and Tarp truncation mutants were analyzed using Total Internal Reflection Fluorescence (TIRF) microscopy. Our data indicate that Tarp mediated actin bundling is independent of actin nucleation and the F-actin binding domains are sufficient to bundle actin filaments. Additionally, Tarp-mediated actin bundles demonstrate distinct bending stiffness compared to those crosslinked by the well characterized actin bundling proteins fascin and alpha-actinin, suggesting Tarp may employ a novel actin bundling strategy. The capacity of the Tarp effector to generate novel actin bundles likely contributes to chlamydia's efficient mechanism of entry into human cells.

Publication Date

6-2-2018

Publication Title

Biochemical and Biophysical Research Communications

Volume

500

Issue

2

Number of Pages

423-428

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.bbrc.2018.04.093

Socpus ID

85045433569 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85045433569

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