Cyclic-di-GMP signalling meets extracellular polysaccharide synthesis in Bacillus subtilis.

In order to resist harmful environmental conditions, many bacteria form multicellular aggregates called biofilms. In these biofilms, they protect themselves in a self-produced matrix consisting of extracellular polysaccharides, proteins and DNA. In many bacteria, biofilm formation is stimulated in the presence of the second messenger cyclic di-GMP. In this issue of Environmental Microbiology Reports, Bedrunka and Graumann have studied matrix production by the proteins encoded in the Bacillus subtilis ydaJKLMN operon. For the first time, they were able to provide a link between c-di-GMP signalling and matrix production in this bacterium. The work demonstrates that the c-di-GMP receptor protein YdaK forms a membrane-bound complex with the YdaM and YdaN proteins, and that this interaction with YdaK is required for polysaccharide production by YdaL, YdaM and YdaN.