Molecular Cell, 19 May, 2021, DOI：
Viral tegument proteins restrict cGAS-DNA phase separation to mediate immune evasion
Guangjun Xu, Chong Liu, Sheng Zhou, Quanjin Li, Yun Feng, Panpan Sun, Han Feng, Yina Gao, Jingpeng Zhu, Xiu Luo, Qi Zhan, Songqing Liu, Shu Zhu, Hongyu Deng, Dong Li, Pu Gao
DNA-induced liquid-liquid phase separation of cyclic GMP-AMP synthase (cGAS) triggers a potent response to detect pathogen infection and promote innate immune signaling. Whether and how pathogens manipulate cGAS-DNA condensation to mediate immune evasion is unknown. We report the identification of a structurally related viral tegument protein family, represented by ORF52 and VP22 from gamma- and alpha-herpesvirinae, respectively, that employs a conserved mechanism to restrict cGAS-DNA phase separation. ORF52/VP22 proteins accumulate into, and effectively disrupt, the pre-formed cGAS-DNA condensation both in vitro and in cells. The inhibition process is dependent on DNA-induced liquid-liquid phase separation of the viral protein rather than a direct interaction with cGAS. Moreover, highly abundant ORF52 proteins carried within viral particles are able to target cGAS-DNA phase separation in early infection stage. Our results define ORF52/VP22-type tegument proteins as a family of inhibitors targeting cGAS-DNA phase separation and demonstrate a mechanism for how viruses overcome innate immunity.