The Chlamydia effector TarP mimics the mammalian leucine-aspartic acid motif of paxillin to subvert the focal adhesion kinase during invasion.
Bottom Line: The conserved leucine residues within the L(D/E)XLLXXL motif were essential to the recruitment of FAK, Cdc42, p34(Arc), and actin to the plasma membrane.In the absence of FAK, TarP-LD-mediated F-actin assembly was reduced, highlighting the functional relevance of this interaction.Together, the data indicate that a prokaryotic version of the paxillin LD2 domain targets the FAK signaling pathway, with TarP representing the first example of an LD-containing Type III virulence effector.
Affiliation: From the Centre for Molecular Microbiology and Infection, Imperial College, London SW7 2AZ, United Kingdom, Bacteriology Section, Programme in Microbiology, Institute of Medical Sciences, School of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom, and.Show MeSH
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Mentions: First, the recruitment of Cdc42 reported by Subtil et al. (20) was verified by infecting EGFP-Cdc42-expressing cells with CMTPX-labeled C. caviae strain GPIC and monitoring EGFP-Cdc42 recruitment by live-cell microscopy (Fig. 9A) at 30-s intervals. As with EGFP-FAK, the recruitment was rapid and transient. Having established Cdc42 recruitment during chlamydial invasion, the molecular basis for this event was investigated using the EPEC system described above. Different deletion derivatives of TarP were evaluated for their ability to support the recruitment of EGFP-Cdc42 to the plasma membrane. By enumerating the incidence of recruitment, we found that those constructs that retained recruitment of FAK and actin also were able to recruit Cdc42. Fig. 9B showed that TarP1–714 was able to support Cdc42 recruitment, but progressive deletion (TarP1–639) significantly reduced recruitment incidence to the level of the negative control TirM (3-fold difference versus TirM; p < 0.005). Furthermore, TarP-LD was sufficient to recruit Cdc42 (3-fold difference versus TirM; p < 0.001). Importantly, the conserved Leu residues were essential, with TarP-mutLD displaying a 3-fold decrease in EGFP-Cdc42 recruitment (Fig. 9B). Fig. 9C shows representative images of EGFP-Cdc42 recruitment by select TirM-TarP constructs.
Affiliation: From the Centre for Molecular Microbiology and Infection, Imperial College, London SW7 2AZ, United Kingdom, Bacteriology Section, Programme in Microbiology, Institute of Medical Sciences, School of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom, and.