Reniere Michelle L, Whiteley Aaron T, Hamilton Keri L, John Sonya M, Lauer Peter, Brennan Richard G, Portnoy Daniel A
Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.
Graduate Group in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, California 94720, USA.
Nature. 2015 Jan 8;517(7533):170-3. doi: 10.1038/nature14029.
Intracellular pathogens are responsible for much of the world-wide morbidity and mortality due to infectious diseases. To colonize their hosts successfully, pathogens must sense their environment and regulate virulence gene expression appropriately. Accordingly, on entry into mammalian cells, the facultative intracellular bacterial pathogen Listeria monocytogenes remodels its transcriptional program by activating the master virulence regulator PrfA. Here we show that bacterial and host-derived glutathione are required to activate PrfA. In this study a genetic selection led to the identification of a bacterial mutant in glutathione synthase that exhibited reduced virulence gene expression and was attenuated 150-fold in mice. Genome sequencing of suppressor mutants that arose spontaneously in vivo revealed a single nucleotide change in prfA that locks the protein in the active conformation (PrfA*) and completely bypassed the requirement for glutathione during infection. Biochemical and genetic studies support a model in which glutathione-dependent PrfA activation is mediated by allosteric binding of glutathione to PrfA. Whereas glutathione and other low-molecular-weight thiols have important roles in redox homeostasis in all forms of life, here we demonstrate that glutathione represents a critical signalling molecule that activates the virulence of an intracellular pathogen.
细胞内病原体是导致全球范围内因传染病而发病和死亡的主要原因。为了成功定殖于宿主，病原体必须感知其环境并适当地调节毒力基因表达。因此，兼性细胞内细菌病原体单核细胞增生李斯特菌在进入哺乳动物细胞后，通过激活主要毒力调节因子PrfA重塑其转录程序。在此我们表明，细菌和宿主来源的谷胱甘肽是激活PrfA所必需的。在本研究中，通过遗传筛选鉴定出一种谷胱甘肽合酶中的细菌突变体，该突变体表现出毒力基因表达降低，并且在小鼠中的毒力减弱了150倍。对体内自发产生的抑制突变体进行基因组测序，发现在prfA中有一个单核苷酸变化，该变化使蛋白质锁定在活性构象（PrfA*），并在感染过程中完全绕过了对谷胱甘肽的需求。生化和遗传研究支持一种模型，即谷胱甘肽依赖性PrfA激活是由谷胱甘肽与PrfA的变构结合介导的。虽然谷胱甘肽和其他低分子量硫醇在所有生命形式的氧化还原稳态中都起着重要作用，但在此我们证明谷胱甘肽是一种关键的信号分子，可激活细胞内病原体的毒力。
