How pathogens can turn off mitochondrial defense mechanisms

The parasite Toxoplasma gondii (red) causes mitochondria (green) to shed large structures of their “skin” (yellow). Credit: Xianhe Li/Max Planck Institute for Gerontology

Mitochondria are known to be the energy suppliers of our cells, but they also play an important role in defense against pathogens. They can initiate immune responses, depriving pathogens of the nutrients they need to thrive. A research team led by Lena Bernas of the Max Planck Institute for Biology of Aging in Cologne, Germany, has shown that pathogens can turn off mitochondrial defense mechanisms by hijacking the normal cellular response to stress.

To survive, pathogens need to obtain nutrients from their host and fight their defenses. One of these defenses comes from the host’s mitochondria, which can deprive them of the nutrients they need and thus restrict their growth. “We wanted to know how mitochondrial behavior also changes when mitochondria and pathogens meet in cells. Since the outer membrane of these organelles is the first point of contact with pathogens, we took a closer look at it,” explains Lena Pernas, research group leader at the Max Planck Institute for Biology. aging.

Mitochondria shed their skin

The researchers infected cells with the human parasite Toxoplasma gondii and observed, live under a microscope, what happens to the outer space of the mitochondria. “We saw that the mitochondria that were in contact with the parasite started shedding large structures from their outer membrane. This was very confusing to us. Why do mitochondria fall off? What is essentially the gateway between them and the rest of the cell?” says Xianhe Li, first author of the study.


But how does a parasite make mitochondria do that? The research team was able to show that the pathogen contains a protein that functionally mimics the host’s mitochondrial protein. It binds to a receptor on the outer mitochondrial membrane, to access the mechanism that ensures the transport of proteins within the mitochondria. “In doing so, the parasite hijacks the host’s natural response to mitochondrial stress, which, in the context of infection, effectively disarms the mitochondria,” Bernas said. “Other researchers have shown that the SARS-CoV-2 virus protein also binds to this transduction receptor. This indicates that the receptor plays an important role in host-pathogen interaction. But further investigation is needed to better understand its role during various infections.”

The search was published in Science.

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more information:
Xianhe Li et al, Mitochondria shed their outer membrane in response to infection-induced stress, Science (2022). DOI: 10.1126/science.abi4343.

Presented by the Max Planck Society

the quote: How Pathogens Can Turn Off Mitochondrial Defense Mechanisms (2022, January 14) Retrieved January 15, 2022 from

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