Research

How mycobacteria leave cells after infection

Mycobacteria like Mycobacterium tuberculosis reside and multiply inside our cells. While their invasion and survival are under intense investigation, it is largely unknown how they leave the cells – something they need to do to spread the infection.

Transmission electron microscopy image of a mycobacterium during its exit from a cell („egress“). Marked is an inclusion body (autophagosome) at the rear pole of the bacterium, which will close the membrane gap after egress has been completed.
Transmission electron microscopy image of a mycobacterium during its exit from a cell („egress“). Marked is an inclusion body (autophagosome) at the rear pole of the bacterium, which will close the membrane gap after egress has been completed.

During their exit, the cells mostly remain intact. We investigated how intracellular pathogens perforate the membranes of their host cells so gently. The host cells, like many other cells, can form intracellular inclusion bodies („autophagosomes“), which are surrounded by a membrane and digest non-functional metabolic compounds and recycle the degradation products back into the cell. We have found that these inclusion bodies move at the rear pole of mycobacteria to the site of exit and close the membrane gap the bacteria leave behind. This observation raises the question whether such inclusion bodies also fix holes in cellular membranes caused by other kinds of injuries.

 


Gerstenmaier L. et al., Proc Natl Acad Sci USA 2015, 112:E687-92

Lilli Gerstenmaier, Rachel Pilla, Lydia Herrmann, Hendrik Herrmann, Monica Prado, Margot Kolonko, Monica Hagedorn and 
external co-operation partners (see publication)