Bacteria have been found to form unexpected alliances with their host cells, a discovery that could lead to new treatments for diseases caused by these pathogens.
Researchers from the Lamason Lab at MIT have discovered a new interaction between an intracellular bacterial pathogen and a eukaryotic membrane. The study, published in the Journal of Cell Biology, shows that Rickettsia parkeri, a bacterial pathogen that lives freely in the cytosol, can interact extensively and stably with the rough endoplasmic reticulum (ER).
This interaction is significant because it is the first known example of a direct interkingdom contact site between an intracellular bacterial pathogen and a eukaryotic membrane. The ER is a vast and dynamic organelle that establishes contact and communication with other organelles, regulating various cellular processes such as fat metabolism, sugar metabolism, and immune responses.
The researchers used focused ion beam scanning electron microscopy to observe the interaction between R. parkeri and the ER at high resolution. They found that less than 5% of R. parkeri formed connections with the ER, but these interactions were critical for the pathogen’s life cycle.
Interestingly, the ER only interacted with nonmotile R. parkeri, which are unable to form actin tails. Mutants that couldn’t form tails showed a 25-fold increase in ER interactions. The researchers also found that VAP proteins, which mediate ER interactions with other organelles, were recruited to the bacteria during infection.
The study suggests that manipulating the organelle that establishes contact with other organelles could be a great way for pathogens to gain control during infection. The Lamason Lab is continuing to explore the molecular players involved in this interaction and its effects on the host or bacteria’s life cycle.
This research has significant implications for our understanding of how pathogens interact with eukaryotic cells and could lead to new treatment options for understudied pathogens like Rickettsia rickettsii, which causes Rocky Mountain Spotted Fever.
