Image credit: Tzu-Ping Ko, Yu-Chuan Wang, Chia-Shin Yang, Mei-Hui Hou, Chao-Jung Chen, Yi-Fang Chiu & Yeh Chen. Crystal structure and functional implication of bacterial STING. Nature Communications 13, Article number 26 (2022). DOI: 10.1038/s41467-021-26583-3 Figure 1 (a) and (b). 

Ko et al. reports the crystal structures of Prevotella corpis STING and Myroides sp. ZB35 STING in Nature Communications 13, Article number 26, published 10 January 2022. PcSTING crystals were obtained in 0.1 M HEPES pH 7.5, 0.2 M calcium chloride dihydrate, 28% v/v polyethylene glycol 400 using 6.5 mg/ml while MySTING crystals grew in 0.1 M sodium cacodylate trihydrate pH 6.5, 0.2 M sodium acetate trihydrate, 15% w/v polyethylene glycol 8,000 using 4 mg/ml. The protein concentrations were determined from the Pre-Crystallization Test. PcSTING crystals were used as seeds to grow the SeMet-labeled PcSTING crystals in 0.1 M sodium cacodylate trihydrate pH 6.5, 0.2 M sodium acetate trihydrate, 18% w/v polyethylene glycol 8,000. The crystal structures showed the bacterial secondary messenger, cyclic di-GMP bound to STING.