How the stressosome integrates and transmits stress signals from the environment has remained elusive. The stressosome consists of multiple copies of three proteins RsbR, RsbS and RsbT, a kinase that is important for its activation. Using cryo-electron microscopy, we determined the atomic organization of the 1.8 megadalton Listeria monocytogenes stressosome at 3.38Å resolution. RsbR and RsbS are organized in a 60 protomers truncated icosahedron. A key phosphorylation site on RsbR (T209) is partially hidden by an RsbR flexible loop, whose “open” or “closed” position could modulate stressosome activity. Interaction between three glutamic acids in the N-terminal domain of RsbR and the membrane-bound mini-protein Prli42 are essential for Listeria survival to stress. Together, our data reveal the structure and function of the core assembly of the stressosome, and describe the discovery of a loop that is important for stressosome activation, paving the way towards elucidating the mechanism of signal transduction in the bacteria.
For more information: https://research.pasteur.fr/en/member/allison-williams/