Bacteria Study Sheds Light on Cell Communication

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Scientists have known for years that bacterial cells use molecules on their surfaces called receptors to help them sense and respond to their environment. Somehow, bacteria are able to sense vanishingly small amounts of an environmental signal--like a nutrient--and then amplify the signal significantly to prompt a quick reaction, such as moving toward food or away from danger. Until recently, scientists were mystified as to how this signal amplification takes place.

Dr. Laura L. Kiessling of the University of Wisconsin, Madison, has uncovered a system that bacterial cells use to sense, analyze, and deliver signals to the cell interior. She chemically manufactured multi-pronged molecules that would attach not to one, but to an entire group of cell-surface receptors called chemoreceptors. These synthetic molecules allowed Dr. Kiessling to control and study cell responses such as bacterial cell motion. She found that bacterial chemoreceptors that sense food and other chemicals in a cell's environment team up in groups to amplify a signal and orchestrate an appropriate response. Chemoreceptors do this, she discovered, by snuggling together on the cell surface into a lattice-type structure that acts sort of like a molecular "nose."

The work may allow researchers to create chemically treated surfaces that repel dangerous microbes on contact. Better knowledge of cell communication among bacteria could also help scientists learn how to dismantle complex “neighborhoods” of communicating bacteria called biofilms, which can coat the surfaces of catheters and other medical devices. Biofilms play a role in a variety of illnesses, including cystic fibrosis and Legionnaire's disease, and infections caused by these bacterial complexes are notoriously resistant to antibiotics. Researchers suspect that human immune cell receptors work in teams, similar to the behavior of E. coli bacteria demonstrated in this study. Further investigations might be able to confirm these suspicions and advance progress in understanding the human immune system.