A Chlamydia effector recruits CEP170 to reprogram host microtubule organization

Abstract

The obligate intracellular bacterial pathogen Chlamydia trachomatis deploys virulence effectors to subvert host cell functions enabling its replication within a specialized membrane-bound compartment termed an inclusion. The control of the host cytoskeleton is crucial for Chlamydia uptake, inclusion biogenesis and cell exit. Here, we demonstrate how a Chlamydia effector rearranges the microtubule (MT) network by initiating organization of the MTs at the inclusion surface. We identified an inclusion-localized effector that is sufficient to interfere with MT assembly, which we named inclusion protein acting on MTs (IPAM). We established that IPAM recruits and stimulates the centrosomal protein 170 kDa (CEP170) to hijack the MT organizing functions of the host cell. We show that CEP170 is essential for chlamydial control of host MT assembly, and is required for inclusion morphogenesis and bacterial infectivity. Together, we demonstrate how a pathogen effector reprograms the host MT network to support its intracellular development.

Chlamydia cell biology and pathogenesis

“…The recruitment and assembly of F-actin involves RHO-family GTPases 49 , septins 94 , EGFR signalling 95 and at least one bacterial effector, InaC 81 . Microtubules are also actively reorganized around the inclusion by IPAM in C. trachomatis , which hijacks a centrosome protein, the centrosomal protein of 170 kDa (CEP170) 96 . This interaction initiates the organization of microtubules at the inclusion surface, which leads to the formation of a microtubule superstructure that is necessary for preserving membrane integrity 96,49 .…”

Structural basis for the hijacking of endosomal sorting nexin proteins by Chlamydia trachomatis

“…The cytoplasmic N- and C-terminal sequences of the Inc proteins act to bind and manipulate host cell proteins. Reported examples include the binding of the small GTPase Rab4A by CT229 (Rzomp et al, 2006), Rab11A by Cpn0585 (Cortes et al, 2007), SNARE proteins by IncA (Delevoye et al, 2008), centrosomal and cytoskeletal proteins by Inc850 and inclusion protein acting on microtubules (IPAM) (Dumoux et al, 2015; Mital et al, 2015, 2010), myosin phosphatase by CT228 (Lutter et al, 2013), 14-3-3 and Arf family proteins by IncG and InaC (Kokes et al, 2015; Scidmore and Hackstadt, 2001), and the lipid transfer protein CERT by IncD (Derré et al, 2011; Elwell et al, 2011). Despite these reports, there are no known structures of Inc family members either alone or in complex with host effectors.

10.7554/eLife.22311.003Figure 1.SNX5, SNX6 and SNX32 tare recruited to C. trachomatis inclusions.( A ) HeLa cells stably expressing the mCherry-Rab25 inclusion membrane marker (red) were infected with C. trachomatis serovar L2 (24 hr) and transfected with myc-tagged SNX expression constructs.

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Expression of Francisella pathogenicity island protein intracellular growth locus E (IglE) in mammalian cells is involved in intracellular trafficking, possibly through microtubule organizing center

“…In Pseudomonas aeruginosa , the T6SS effector VgrG2b associates with the γ‐TuRC, facilitating internalization of the bacterium (Sana et al., ). The Chlamydia trachomatis T3SS effector IPAM interacts with the MTOC protein CEP170 and controls microtubule assembly for inclusion morphogenesis (Dumoux, Menny, Delacour, & Hayward, ). Our findings suggest that IglE associates with MTOCs and controls membrane trafficking on microtubules.…”