Background: Chlamydia trachomatis (CT) is a major human pathogen and the leading cause of bacterial sexually transmitted infections. Infections in women are most often asymptomatic, but if the bacterium ascends to into the oviduct it can cause more serious disease. Current therapies to eradicate Chlamydia genital tract infections employ broad-spectrum antibiotics that have profound effects on the vaginal microbiota that can lead to vulvovaginal candidiasis or bacterial vaginosis, which reduce the quality of life for women. A therapeutic vaccine against CT is currently unavailable which underlines the importance of creating a targeted treatment for these infections. In contrast to the majority of bacteria that divide by binary fission, Chlamydia trachomatis divides by polarized budding.

Methods: To define the mechanisms that regulate this novel division process, we analyzed the localization patterns of key regulators of bacterial division, PBP2, PBP3, and MreC. M-Cherry PBP2, M-Cherry PBP3 and M-Cherry MreC fusions were introduced into the plasmid, pBOMB4. CT serovar L2 was transformed with these constructs that allowed for the inducible expression of the fusions by the addition of anhydrotetracycline (aTC) to the media. HeLa cells were infected with the transformants and the fusions were induced. The Chlamydia were then isolated from infected cells, fixed to a slide, and analyzed, using conventional epifluorescence microscopy.

Results: Analyses revealed that PBP2, PBP3, and MreC primarily accumulated in a spot at the septum between the mother and daughter cell during polarized division.

Conclusions: The localization profiles of these proteins are distinct from their localization in other bacteria, and they suggest that chlamydial PBPs may interact with peptidoglycan in a manner very different than that seen in other bacteria. The nature of this interaction will be investigated in future real-time imaging studies.

References and Resources

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