What makes a good killer?

Our body is protected against bacterial infections by specialized cells (macrophages and neutrophils) that eat and kill bacteria. To better understand this process, it is important to know how cells kill bacteria. Amoebae mimic the behavior of macrophages and neutrophils and are good model organisms to study bacterial killing. Like our specialized cells, amoebae can use different types of killing strategies ranging from low pH to free radicals. However, the relative importance of different killing mechanisms, their redundancy, and their specificity are still unclear.

What biochemistry tells us

In a recent study published in frontiers in cellular and infection microbiology, researchers from the group of Pr. Pierre Cosson identified a particular protein required to destroy a bacteria called Klebsiella pneumoniae. They noted that this protein alone was not sufficient to kill bacteria, suggesting that a single weapon might not be enough to kill a bacteria.

Does genetics tell the same story?

In parallel, the research team used also a genetic approach to identify the genes involved in the killing of five different bacteria. Their experiments published in mBio showed that radically different mechanisms were required to kill these different bacteria, suggesting that the weaponry used to kill a particular bacteria is not necessarily efficient to kill another one.

No universal weapon against bacteria

The identified proteins and genes in these two studies reveal that there is no universal weapon that kills all bacteria, but instead specific weapons for each bacteria. This unexpected finding tells us that a lot remains to be discovered about how phagocytic cells eliminate bacteria. Researchers from Pr. Pierre Cosson laboratory aim now at identifying additional proteins/genes involved in bacterial killing and gain a more complete understanding of their mechanism of action.

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