Bacteria are particularly harmful to human health when they band together to form a biofilm—a sheet composed of many individual bacteria glued together—because this can allow them to escape from both antibiotics and the immune system of their host. It is thought that most chronic infections are caused by bacterial biofilms, and a paper published in this week’s PLoS Biology explores the signalling system that causes bacteria to team up in this way.

Pseudomonas is the pathogen that forms biofilms in the lungs of people with cystic fibrosis. The new paper, from Holger Sondermann and colleagues, identifies a novel kind of control system for bacterial signalling. Bacteria form a biofilm when the concentration of a molecule called c-di-GMP gets above a certain threshold. Sondermann et al. have determined the structure of the enzyme that makes c-di-GMP. The enzyme is called WspR in Pseudomonas, and the way WspR is controlled in the cell is the focus of their paper. … Continue Reading »