Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois, USA.
Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois, USA
Infect Immun. 2021 Mar 17;89(4). doi: 10.1128/IAI.00700-20.
The Gram-positive bacterium survives in environments ranging from the soil to the cytosol of infected host cells. Key to intracellular survival is the activation of PrfA, a transcriptional regulator that is required for the expression of multiple bacterial virulence factors. Mutations that constitutively activate ( mutations) result in high-level expression of multiple bacterial virulence factors as well as the physiological adaptation of for optimal replication within host cells. Here, we demonstrate that mutants exhibit significantly enhanced resistance to oxidative stress in comparison to that of wild-type strains. Transposon mutagenesis of strains resulted in the identification of three novel gene targets required for full oxidative stress resistance only in the context of PrfA activation. One gene, , predicted to encode an uncharacterized protein, and two additional genes known as and , encoding a cyclic di-AMP binding protein and a 2-C-methyl-d-erythritol 2,4-cyclodiphosphate synthase, respectively, contribute to the enhanced oxidative stress resistance of strains while exhibiting no significant contribution in wild-type Transposon inactivation of and in a background led to reduced virulence in the liver of infected mice. These results indicate that calls upon specific bacterial factors for stress resistance in the context of PrfA activation and thus under conditions favorable for bacterial replication within infected mammalian cells.
革兰氏阳性菌 存在于从土壤到感染宿主细胞胞质溶胶等各种环境中。其在细胞内生存的关键是激活 PrfA，这是一种转录调节剂，是表达多种细菌毒力因子所必需的。持续激活 （突变）会导致多种细菌毒力因子的高水平表达，以及 适应宿主细胞内最佳复制的生理适应。在这里，我们证明与野生型菌株相比， 突变体在氧化应激下具有显著更高的抗性。转座子诱变 菌株导致在 PrfA 激活的情况下仅需要三种新的基因靶标才能完全抵抗氧化应激。一个基因 ，预测编码一种未鉴定的蛋白质，以及另外两个基因 和 ，分别编码环二核苷酸结合蛋白和 2-C-甲基-D-赤藓醇 2,4-环二磷酸合酶，在 菌株中增强了氧化应激抗性，而在野生型菌株中没有显著贡献。在 背景下 和 的转座子失活导致感染小鼠肝脏中的毒力降低。这些结果表明，在 PrfA 激活的情况下， 调用特定的细菌因子来抵抗应激，从而在有利于感染哺乳动物细胞内细菌复制的条件下。
