Abstract
The mammalian protein vinculin is often a target of bacterial pathogens to subvert locally host cell actin dynamics. In Chlamydia infection, vinculin has been implicated in RNA interference screens, but the molecular basis for vinculin requirement has not been characterized. In this report, we show that vinculin was involved in the actin recruitment and F-actin assembly at the plasma membrane to facilitate invasion. Vinculin was recruited to the plasma membrane via its interaction with a specific tripartite motif within TarP that resembles the vinculin-binding domain (VBD) found in the Shigella invasion factor IpaA. The TarP-mediated plasma membrane recruitment of vinculin resulted in the localized recruitment of actin. In vitro pulldown assays for protein-protein interaction and imaging-based evaluation of recruitment to the plasma membrane demonstrated the essential role of the vinculin-binding site 1 (VBS1), and the dispensability of VBS2 and VBS3. As further support for the functionality of VBD-vinculin interaction, VBD-mediated actin recruitment required vinculin. Interestingly, while both vinculin and the focal adhesion kinase (FAK) colocalized at the sites of adhesion, the recruitment of one was independent of the other; and the actin recruitment function of the VBD/vinculin signaling axis was independent of the LD/FAK pathway.
Highlights
In mammalian cells, the actin-binding protein vinculin associates with the cytoplasmic face of focal adhesions to facilitate linkage of integrin molecules to the actin cytoskeleton (Critchley et al, 1999)
Vinculin activation requires the interaction with another focal adhesion protein, talin, which is mechanically stretched upon local application of tensile force at focal adhesions to expose vinculin binding sites (VBS) (Fillingham et al, 2005; Humphries et al, 2007; del Rio et al, 2009; Grashoff et al, 2010)
Given previous findings demonstrating the involvement of various focal adhesion components during Chlamydial infection (Coombes and Mahony, 2002; Elwell et al, 2008; Gurumurthy et al, 2010), we sought to determine in greater detail the involvement of vinculin in Chlamydia invasion
Summary
The actin-binding protein vinculin associates with the cytoplasmic face of focal adhesions to facilitate linkage of integrin molecules to the actin cytoskeleton (Critchley et al, 1999). Intramolecular associations between the head and tail domains constrain vinculin to an inactive state (Johnson and Craig, 1995). Talin initially associates with Vh domain 1 (Vh1) of inactive vinculin through. Switching to an open active conformation allows for complete binding of vinculin to talin (Case et al, 2015). In its active form, vinculin is capable of direct interaction with Arp2/3, actin, phosphatidylinositol (4,5)-bisphosphate (PIP2), and paxillin (Turner et al, 1990; Hüttelmaier et al, 1998; DeMali et al, 2002). The binding of vinculin to talin can facilitate a localized increase in the number actin filaments and the maturation of focal adhesions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
