Bacteria can talk to each other via molecules they themselves produce. The phenomenon is called quorum sensing, and is important when an infection propagates. Now, researchers at Link-ping University in Sweden are showing how bacteria control processes in human cells the same way.
The results are being published in the journal PLOS Pathogens with Elena Vikstr-m, researcher in Medical Microbiology, as the main author.
When an infection is signaled, more and more bacteria gather at the site of the attack - a wound, for example. When there are enough of them, they start acting like multicellular organisms. They can form biofilms, dense structures with powers of resistance against both antibiotics and the body's immune defence system. At the same time, they become more aggressive and increase their mobility. All these changes are triggered when the communication molecules - short fatty acids with the designation AHL - bind to receptors inside the bacterial cells; as a consequence various genes are turned on and off.
AHL can migrate freely through the cell membrane, not just in bacterial cells but also our own cells, which can be influenced to change their functions. In low concentrations white blood cells, for example, can be more flexible and effective, but in high concentrations the opposite occurs, which weakens our immune defences and opens the door for progressive infections and inflammations.
A team at Link-ping University is the first research group in the world to show how AHL can influence their host cells. Using biochemical methods, the researchers have identified a protein designated IQGAP, which they single out as the recipient of the bacteria's message, and something of a double agent.
"The protein can both listen in on the bacteria's communication and change the functions in its host cells," Vikstr-m says.