Cyclic di-GMP Sensing via the Innate Immune Signaling Protein STING.
Yin, Q., Tian, Y., Kabaleeswaran, V., Jiang, X., Tu, D., Eck, M.J., Chen, Z.J., Wu, H.(2012) Mol Cell 46: 735-745
- PubMed: 22705373 
- DOI: https://doi.org/10.1016/j.molcel.2012.05.029
- Primary Citation of Related Structures:  
4F9E, 4F9G - PubMed Abstract: 
Detection of foreign materials is the first step of successful immune responses. Stimulator of interferon genes (STING) was shown to directly bind cyclic diguanylate monophosphate (c-di-GMP), a bacterial second messenger, and to elicit strong interferon responses. Here we elucidate the structural features of the cytosolic c-di-GMP binding domain (CBD) of STING and its complex with c-di-GMP. The CBD exhibits an α + β fold and is a dimer in the crystal and in solution. Surprisingly, one c-di-GMP molecule binds to the central crevice of a STING dimer, using a series of stacking and hydrogen bonding interactions. We show that STING is autoinhibited by an intramolecular interaction between the CBD and the C-terminal tail (CTT) and that c-di-GMP releases STING from this autoinhibition by displacing the CTT. The structures provide a remarkable example of pathogen-host interactions in which a unique microbial molecule directly engages the innate immune system.
Organizational Affiliation: 
Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA. qiy2001@med.cornell.edu