Bacterial cells use both a virus—traditionally thought to be an enemy—and a prehistoric viral protein to kill other bacteria that competes with it for food according to an international team of researchers who believe this has potential implications for future infectious disease treatment.
The team, led by Thomas Wood, holder of the biotechnology endowed chair and professor of chemical engineering, Penn State, noticed a gap between two kinds of bacterial cells as they moved on agar plates toward each other, in a form of motility known as "swimming" where the bacterium moves by rotating its flagella.
The team not only found that a bacterial cell uses the SW1 virus to kill bacteria that are its competitors for food, they also discovered that bacteria that carry the virus are more fit and not killed as often as bacteria without the virus. In addition, they found that for a bacterium to be able to use SW1, it needs a protein fossil of a bacterium that came from another virus millions of years ago. They report their results in a recent issue of Cell Reports.
Wood explained that sometimes a virus will enter a cell and hide in the chromosome until it is ready to attack and kill the cell. However, due to random mutations, a virus sometimes is stuck in the chromosome and cannot leave to attack. There are nine viruses trapped in this way in the beneficial gut bacterium E. coli. To be activated and used by E. coli against other bacteria, the virus SW1 needs a protein, YfdM, from a virus that became caught in the E. coli chromosome millions of years ago.
In addition, the virus is used by the bacterium as an identifier.
If the bacterium does not detect the virus in the other bacterium, it identifies a competitor for food, and unleashes the virus to kill its competition. While the exact workings of this process are not yet understood, it may hold potential benefits for research and medicine.
