Chlamydia trachomatis uses host cell dynein to traffic to the microtubule-organizing center in a p50 dynamitin-independent process

Abstract

Chlamydiae are pathogenic obligate intracellular bacteria with a biphasic developmental cycle that involves cell types adapted for extracellular survival (elementary bodies, EBs) and intracellular multiplication (reticulate bodies, RBs). The intracellular development of chlamydiae occurs entirely within a membrane-bound vacuole termed an inclusion. Within 2 hours after entry into host cells, Chlamydia trachomatis EBs are trafficked to the perinuclear region of the host cell and remain in close proximity to the Golgi apparatus, where they begin to fuse with a subset of host vesicles containing sphingomyelin. Here, we provide evidence that chlamydial migration from the cell periphery to the peri-Golgi region resembles host cell vesicular trafficking. Chlamydiae move towards the minus end of microtubules and aggregate at the microtubule-organizing center (MTOC). In mammalian cells the most important minus-end-directed microtubule motor is cytoplasmic dynein. Microinjection of antibodies to a subunit of cytoplasmic dynein inhibited movement of chlamydiae to the MTOC, whereas microinjection of antibodies to the plus-directed microtubule motor, kinesin, had no effect. Surprisingly, overexpression of the protein p50 dynamitin, a subunit of the dynactin complex that links vesicular cargo to the dynein motor in minus directed vesicle trafficking, did not abrogate chlamydial migration even though host vesicle transport was inhibited. Nascent chlamydial inclusions did, however, colocalize with the p150(Glued) dynactin subunit, which suggests that p150(Glued) may be required for dynein activation or processivity but that the cargo-binding activity of dynactin, supplied by p50 dynamitin subunits and possibly other subunits, is not. Because chlamydial transcription and translation were required for this intracellular trafficking, chlamydial proteins modifying the cytoplasmic face of the inclusion membrane are probable candidates for proteins fulfilling this function.

Microtubule motors control membrane dynamics of Salmonella-containing vacuoles

“…Microtubules are also required for the intracellular movement and cell-to-cell spread of Actinobacillus actinomycetemcomitans (Meyer et al, 1999), and both microtubules and dynein have previously been found to localise around Chlamydia Journal of Cell Science 117 (7) trachomatis-containing vacuoles several hours after infection of epithelial cells (Clausen et al, 1997). Dynein activity is required for migration of C. trachomatis to the peri-Golgi region, although this appears to be independent of p50/dynamitin (Grieshaber et al, 2003). The recent finding from our laboratory that Salmonella microcolonies also develop in close association with the Golgi (Salcedo and Holden, 2003) provides further evidence of similarities in the behaviour of these two intracellular pathogens.…”

Chlamydial Intracellular Survival Strategies

“…Soon after entry, nascent inclusions are transported along microtubules to the microtubule organizing center (MTOC) in a dynein-dependent but dynactin-independent manner (Clausen et al 1997;Grieshaber et al 2003;Grieshaber et al 2006), suggesting that one or more unknown bacterial effectors mimic the cargobinding activity of dynactin and tether the inclusion to dynein and/or to centrosomes. Src family kinases are required in human-adapted Chlamydia strains for inclusions to migrate to the MTOC and for intracellular growth, even though they are dispensable for binding and entry (Mital and Hackstadt 2011).…”

Multinucleate host cells induced by Vittaforma corneae (Microsporidia)

“…As obligate intracellular parasites the microsporidia appear to have been able to reduce their genome size, simplify their organelle structures and reduce their biochemical pathways by subverting the host cell's physiology to provide the missing biochemical support for parasite development (Slamovits et al 2004). As with other intracellular parasites, from viruses to protozoa (e.g., Halonen and Weidner 1994, Risco et al 2002, Grieshaber et al 2003, the microsporidia appear to modify host cell cytoskeleton, organelle arrangement, biochemistry and cell cycle to optimize the intracellular niche (Weidner et al 1999, Scanlon et al 2000. To date, compared with many other infectious agents, relatively little is known about how the microsporidia signal the host cells to affect these many changes that occur in host cell structure and function.…”