A group of researchers led by Dr. Ferric Fang, professor of laboratory medicine and microbiology at the UW School of Medicine, were interested in learning how bacteria respond to genetic information coming from outside sources. Just as immune cells recognize and attack foreign invaders in the human body to protect against harmful infections, single-cell organisms have a protein called H-NS that recognizes foreign DNA and prevents it from becoming active, the researchers discovered.
But bacteria can also benefit from foreign DNA. When Salmonella is infecting an animal or person, for instance, many proteins the bacteria need to cause disease are encoded by DNA acquired from other bacteria. The researchers found that when the bacteria is infecting a host, other molecules can compete with the H-NS protein, allowing the disease-causing genes to be expressed. When the bacteria are in the environment, H-NS turns these genes off to avoid detrimental consequences if all the disease-causing genes were to be expressed at once.
These findings give scientists new insight into how bacteria can protect themselves from an invasion by foreign DNA, yet still take in genetic information from diverse sources that makes them more virulent.
"By harnessing foreign DNA, bacteria that cause typhoid, dysentery, cholera and plague have evolved from harmless organisms into feared pathogens," explained
Source:University of Washington