Khan Mike, Harms Jerome S, Marim Fernanda M, Armon Leah, Hall Cherisse L, Liu Yi-Ping, Banai Menachem, Oliveira Sergio C, Splitter Gary A, Smith Judith A
Cellular and Molecular Pathology Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
Department of Pathobiological Sciences, University of Wisconsin-Madison School of Veterinary Medicine, Madison, Wisconsin, USA.
Infect Immun. 2016 Nov 18;84(12):3458-3470. doi: 10.1128/IAI.00531-16. Print 2016 Dec.
Brucella species are facultative intracellular bacteria that cause brucellosis, a chronic debilitating disease significantly impacting global health and prosperity. Much remains to be learned about how Brucella spp. succeed in sabotaging immune host cells and how Brucella spp. respond to environmental challenges. Multiple types of bacteria employ the prokaryotic second messenger cyclic di-GMP (c-di-GMP) to coordinate responses to shifting environments. To determine the role of c-di-GMP in Brucella physiology and in shaping host-Brucella interactions, we utilized c-di-GMP regulatory enzyme deletion mutants. Our results show that a ΔbpdA phosphodiesterase mutant producing excess c-di-GMP displays marked attenuation in vitro and in vivo during later infections. Although c-di-GMP is known to stimulate the innate sensor STING, surprisingly, the ΔbpdA mutant induced a weaker host immune response than did wild-type Brucella or the low-c-di-GMP guanylate cyclase ΔcgsB mutant. Proteomics analysis revealed that c-di-GMP regulates several processes critical for virulence, including cell wall and biofilm formation, nutrient acquisition, and the type IV secretion system. Finally, ΔbpdA mutants exhibited altered morphology and were hypersensitive to nutrient-limiting conditions. In summary, our results indicate a vital role for c-di-GMP in allowing Brucella to successfully navigate stressful and shifting environments to establish intracellular infection.
布鲁氏菌属是兼性胞内细菌,可引起布鲁氏菌病,这是一种慢性衰弱性疾病,对全球健康和繁荣产生重大影响。关于布鲁氏菌如何成功破坏免疫宿主细胞以及如何应对环境挑战,仍有许多有待了解之处。多种细菌利用原核第二信使环二鸟苷酸(c-di-GMP)来协调对不断变化的环境的反应。为了确定c-di-GMP在布鲁氏菌生理学以及塑造宿主-布鲁氏菌相互作用中的作用,我们利用了c-di-GMP调节酶缺失突变体。我们的结果表明,产生过量c-di-GMP的ΔbpdA磷酸二酯酶突变体在后期感染期间在体外和体内均表现出明显的减毒。尽管已知c-di-GMP可刺激先天性传感器STING,但令人惊讶的是,ΔbpdA突变体诱导的宿主免疫反应比野生型布鲁氏菌或低c-di-GMP鸟苷酸环化酶ΔcgsB突变体弱。蛋白质组学分析表明,c-di-GMP调节几个对毒力至关重要的过程,包括细胞壁和生物膜形成、营养获取以及IV型分泌系统。最后,ΔbpdA突变体表现出形态改变,并且对营养限制条件高度敏感。总之,我们的结果表明c-di-GMP在使布鲁氏菌成功应对压力和不断变化的环境以建立细胞内感染方面起着至关重要的作用。