Institute of Medical Microbiology, Justus-Liebig-University, Giessen, Germany.
PLoS One. 2011;6(9):e24965. doi: 10.1371/journal.pone.0024965. Epub 2011 Sep 30.
Pathogenic bacteria maintain a multifaceted apparatus to resist damage caused by external stimuli. As part of this, the universal stress protein A (UspA) and its homologues, initially discovered in Escherichia coli K-12 were shown to possess an important role in stress resistance and growth in several bacterial species.
We conducted a study to assess the role of three homologous proteins containing the UspA domain in the facultative intracellular human pathogen Listeria monocytogenes under different stress conditions. The growth properties of three UspA deletion mutants (Δlmo0515, Δlmo1580 and Δlmo2673) were examined either following challenge with a sublethal concentration of hydrogen peroxide or under acidic conditions. We also examined their ability for intracellular survival within murine macrophages. Virulence and growth of usp mutants were further characterized in invertebrate and vertebrate infection models. Tolerance to acidic stress was clearly reduced in Δlmo1580 and Δlmo0515, while oxidative stress dramatically diminished growth in all mutants. Survival within macrophages was significantly decreased in Δlmo1580 and Δlmo2673 as compared to the wild-type strain. Viability of infected Galleria mellonella larvae was markedly higher when injected with Δlmo1580 or Δlmo2673 as compared to wild-type strain inoculation, indicating impaired virulence of bacteria lacking these usp genes. Finally, we observed severely restricted growth of all chromosomal deletion mutants in mice livers and spleens as compared to the load of wild-type bacteria following infection.
This work provides distinct evidence that universal stress proteins are strongly involved in listerial stress response and survival under both in vitro and in vivo growth conditions.
病原体维持着一种多方面的机制来抵抗外部刺激造成的损伤。作为其中的一部分，最初在大肠杆菌 K-12 中发现的普遍应激蛋白 A (UspA)及其同源物，被证明在几种细菌物种的应激抗性和生长中具有重要作用。
我们进行了一项研究，以评估三种含有 UspA 结构域的同源蛋白在兼性细胞内人类病原体李斯特菌属 under 不同应激条件下的作用。通过检测亚致死浓度过氧化氢或酸性条件下的生长特性，研究了三种 UspA 缺失突变体（Δlmo0515、Δlmo1580 和 Δlmo2673）的生长特性。还研究了它们在鼠巨噬细胞内的存活能力。usp 突变体的毒力和生长特性在无脊椎动物和脊椎动物感染模型中进一步得到了表征。Δlmo1580 和 Δlmo0515 的酸性应激耐受能力明显降低，而所有突变体的氧化应激都显著抑制了生长。与野生型菌株相比，Δlmo1580 和 Δlmo2673 在内的巨噬细胞内的存活率明显降低。与野生型菌株接种相比，感染的家蚕幼虫用Δlmo1580 或 Δlmo2673 注射后，其存活率明显升高，表明缺乏这些 usp 基因的细菌毒力受损。最后，与野生型细菌感染后的负荷相比，我们观察到所有染色体缺失突变体在小鼠肝脏和脾脏中的生长受到严重限制。
这项工作提供了明确的证据，表明普遍应激蛋白在李斯特菌的应激反应和体外及体内生长条件下的存活中都有强烈的参与。
