Sycz Gabriela, Carrica Mariela Carmen, Tseng Tong-Seung, Bogomolni Roberto A, Briggs Winslow R, Goldbaum Fernando A, Paris Gastón
Laboratorio de Inmunología y Microbiología Molecular, Fundación Instituto Leloir (IIBBA-CONICET), Buenos Aires, Argentina.
Department of Plant Biology, Carnegie Institution for Science, Stanford, California, United States of America.
PLoS One. 2015 May 19;10(5):e0124058. doi: 10.1371/journal.pone.0124058. eCollection 2015.
Brucella is the causative agent of the zoonotic disease brucellosis, and its success as an intracellular pathogen relies on its ability to adapt to the harsh environmental conditions that it encounters inside the host. The Brucella genome encodes a sensor histidine kinase containing a LOV domain upstream from the kinase, LOVHK, which plays an important role in light-regulated Brucella virulence. In this report we study the intracellular signaling pathway initiated by the light sensor LOVHK using an integrated biochemical and genetic approach. From results of bacterial two-hybrid assays and phosphotransfer experiments we demonstrate that LOVHK functionally interacts with two response regulators: PhyR and LovR, constituting a functional two-component signal-transduction system. LOVHK contributes to the activation of the General Stress Response (GSR) system in Brucella via PhyR, while LovR is proposed to be a phosphate-sink for LOVHK, decreasing its phosphorylation state. We also show that in the absence of LOVHK the expression of the virB operon is down-regulated. In conclusion, our results suggest that LOVHK positively regulates the GSR system in vivo, and has an effect on the expression of the virB operon. The proposed regulatory network suggests a similar role for LOVHK in other microorganisms.
布鲁氏菌是人畜共患病布鲁氏菌病的病原体，其作为细胞内病原体的成功依赖于它适应在宿主体内遇到的恶劣环境条件的能力。布鲁氏菌基因组编码一种传感器组氨酸激酶，该激酶在激酶上游含有一个LOV结构域，即LOVHK，它在光调节的布鲁氏菌毒力中起重要作用。在本报告中，我们使用综合的生化和遗传学方法研究由光传感器LOVHK启动的细胞内信号通路。从细菌双杂交试验和磷酸转移实验的结果来看，我们证明LOVHK与两个应答调节因子：PhyR和LovR发生功能相互作用，构成一个功能性的双组分信号转导系统。LOVHK通过PhyR促进布鲁氏菌中一般应激反应（GSR）系统的激活，而LovR被认为是LOVHK的一个磷酸阱，降低其磷酸化状态。我们还表明，在没有LOVHK的情况下，virB操纵子的表达下调。总之，我们的结果表明，LOVHK在体内正向调节GSR系统，并对virB操纵子的表达有影响。所提出的调控网络表明LOVHK在其他微生物中具有类似作用。
