Huang Kaisong, Wang Dan, Frederiksen Rikki F, Rensing Christopher, Olsen John E, Fresno Ana H
Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.
Front Microbiol. 2018 Jan 11;8:2656. doi: 10.3389/fmicb.2017.02656. eCollection 2017.
The transition metal zinc is involved in crucial biological processes in all living organisms and is essential for survival of in the host. However, little is known about the role of genes encoding zinc efflux transporters during infection. In this study, we constructed deletion mutants for genes encoding zinc exporters (, , and ) in the wild-type (WT) strain serovar Typhimurium ( Typhimurium) 4/74. The mutants 4/74Δ and 4/74Δ exhibited a dramatic growth delay and abrogated growth ability, respectively, in Luria Bertani medium supplemented with 0.25 mM ZnCl or 1.5 mM CuSO compared to the WT strain. In order to investigate the role of genes encoding zinc exporters on survival of Typhimurium inside cells, amoeba and macrophage infection models were used. No significant differences in uptake or survival were detected for any of the mutants compared to the WT during infection of amoebae. In natural resistance-associated macrophage protein 1 (Nramp1)-negative J774.1 murine macrophages, significantly higher bacterial counts were observed for the mutant strains 4/74Δ and 4/74Δ compared to the WT at 4 h post-infection although the fold net replication was similar between all the strains. All four tested mutants (4/74Δ, 4/74Δ, 4/74Δ, and 4/74Δ) showed enhanced intracellular survival capacity within the modified Nramp1-positive murine RAW264.7 macrophages at 20 h post-infection. The fold net replication was also significantly higher for 4/74Δ, 4/74Δ, and 4/74Δ mutants compared to the WT. Intriguingly, the ability to survive and cause infection was significantly impaired in all the three mutants tested (4/74Δ, 4/74Δ, and 4/74Δ) in C3H/HeN mice, particularly the double mutant 4/74Δ was severely attenuated compared to the WT in all the three organs analyzed. These findings suggest that these genes encoding zinc exporters, especially , contribute to the resistance of Typhimurium to zinc and copper stresses during infection.
过渡金属锌参与所有生物体的关键生物过程,对宿主的生存至关重要。然而,关于编码锌外流转运蛋白的基因在感染过程中的作用却知之甚少。在本研究中,我们构建了野生型(WT)鼠伤寒沙门氏菌血清型鼠伤寒4/74中编码锌输出蛋白(、和)的基因的缺失突变体。与WT菌株相比,突变体4/74Δ和4/74Δ在补充有0.25 mM ZnCl或1.5 mM CuSO的Luria Bertani培养基中分别表现出显著的生长延迟和生长能力丧失。为了研究编码锌输出蛋白的基因对鼠伤寒沙门氏菌在细胞内存活的作用,使用了变形虫和巨噬细胞感染模型。在感染变形虫期间,与WT相比,未检测到任何突变体在摄取或存活方面有显著差异。在天然抗性相关巨噬细胞蛋白1(Nramp1)阴性的J774.1小鼠巨噬细胞中,尽管所有菌株之间的净复制倍数相似,但在感染后4小时,与WT相比,突变菌株4/74Δ和4/74Δ的细菌计数显著更高。所有四个测试突变体(4/74Δ、4/74Δ、4/74Δ和4/74Δ)在感染后20小时在改良的Nramp1阳性小鼠RAW264.7巨噬细胞内均表现出增强的细胞内存活能力。与WT相比,4/74Δ、4/74Δ和4/74Δ突变体的净复制倍数也显著更高。有趣的是,在C3H/HeN小鼠中测试的所有三个突变体(4/74Δ、4/74Δ和4/74Δ)的存活和引起感染的能力均显著受损,特别是双突变体4/74Δ与WT相比,在所有分析的三个器官中均严重减毒。这些发现表明,这些编码锌输出蛋白的基因,特别是,有助于鼠伤寒沙门氏菌在感染期间对锌和铜胁迫的抗性。