Wang Xiao, Hao Xinwei, Yang Yuqing, Jia Siyu, Chen Yating, Yang Wenguang, Luo Yi, Xie Zhen, Gu Yanchao, Wu Yuxuan, Zhang Fuhua, Li Mengyuan, Wang Yao, Shen Xihui, Xu Lei
State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China.
State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China.
Vet Microbiol. 2024 Oct;297:110194. doi: 10.1016/j.vetmic.2024.110194. Epub 2024 Jul 22.
Yersinia pseudotuberculosis (Yptb) is a pathogenic gram-negative bacterium that can colonize the intestines of different animals. Its infection leads to the activation of the host's innate immunity. Both host and bacterial-derived cyclic dinucleotides (CDNs) could activate the innate immune response of host cells. In bacteria, CDNs like c-di-AMP, c-di-GMP, or 3'3'-cGAMP can be hydrolyzed by different hydrolases. Recent studies showed that the degradation of those second messengers helps the pathogen evade immune detection. In this study, we identified a hydrolase, YPK_3776, namely CpdB in Yptb. CpdB is predicted to bind bacterial-derived c-di-AMP, c-di-GMP, 3'3'-cGAMP and host-derived 2'3'-cGAMP. Surprisingly, by using high-performance liquid chromatography (HPLC), we found that CpdB could only degrade bacterial-derived CDNs but not host-derived 2'3'-cGAMP. In addition, CpdB has 2'3'-cNMP activity. Consistently, the Yptb mutant lacking the cpdB gene exhibited a higher level of intracellular c-di-GMP. Furthermore, the ∆cpdB mutant elicited stronger innate immune responses during Yptb infection in macrophages, suggesting CpdB enables Yptb to evade host immune surveillance. Furthermore, CpdB inhibited the Yptb-induced innate immune response in a STING-dependent manner. Finally, we showed the ∆cpdB infection in mice model exhibited in lower bacterial burden, as compared to wild-type strain infection, indicating CpdB is important for bacterial survival in the host. Together, we identified a cyclic dinucleotide hydrolase CpdB in Yptb that could degrade bacterial-derived CDNs which help the pathogen to evade immune detection via the STING pathway.
假结核耶尔森菌（Yptb）是一种致病性革兰氏阴性细菌，可在不同动物的肠道中定殖。其感染会导致宿主先天免疫的激活。宿主和细菌来源的环二核苷酸（CDN）均可激活宿主细胞的先天免疫反应。在细菌中，像环二腺苷酸（c-di-AMP）、环二鸟苷酸（c-di-GMP）或3'3'-环鸟苷酸腺苷酸（3'3'-cGAMP）这样的CDN可被不同的水解酶水解。最近的研究表明，这些第二信使的降解有助于病原体逃避免疫检测。在本研究中，我们鉴定了一种水解酶，即Yptb中的YPK_3776，也就是CpdB。预测CpdB可结合细菌来源的c-di-AMP、c-di-GMP、3'3'-cGAMP以及宿主来源的2'3'-cGAMP。令人惊讶的是，通过高效液相色谱（HPLC），我们发现CpdB只能降解细菌来源的CDN，而不能降解宿主来源的2'3'-cGAMP。此外，CpdB具有2'3'-环核苷酸单磷酸（2'3'-cNMP）活性。一致的是，缺失cpdB基因的Yptb突变体表现出更高水平的细胞内环二鸟苷酸。此外，在巨噬细胞感染Yptb期间，∆cpdB突变体引发了更强 的先天免疫反应，这表明CpdB使Yptb能够逃避宿主免疫监视。此外，CpdB以一种依赖于干扰素基因刺激蛋白（STING）的方式抑制Yptb诱导的先天免疫反应。最后，我们发现与野生型菌株感染相比，在小鼠模型中∆cpdB感染的细菌载量更低，这表明CpdB对细菌在宿主体内的存活很重要。总之，我们在Yptb中鉴定了一种环二核苷酸水解酶CpdB，它可以降解细菌来源的CDN，这有助于病原体通过STING途径逃避免疫检测。
