Gregory Anna L, Bussan Hailey E, Topf Madeline A, Hryckowian Andrew J
Department of Medicine, Division of Gastroenterology and Hepatology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
Department of Medical Microbiology & Immunology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
bioRxiv. 2024 Oct 30:2024.10.30.621113. doi: 10.1101/2024.10.30.621113.
infection (CDI), characterized by colitis and diarrhea, afflicts approximately half a million people in the United States every year, burdening both individuals and the healthcare system. 630Δ is an erythromycin-sensitive variant of the clinical isolate 630 and is commonly used in the research community due to its genetic tractability. 630Δ possesses a point mutation in , an autoregulated transcriptional repressor that regulates oxidative stress resistance genes. This point mutation results in a constitutively de-repressed PerR operon in 630Δ. To address the impacts of on phenotypes relevant for oxygen tolerance and relevant to a murine model of CDI, we corrected the point mutant to restore PerR function in 630Δ (herein, 630Δ ). We demonstrate that there is no difference in growth between 630Δ and a 630Δ under anaerobic conditions or when exposed to concentrations of O that mimic those found near the surface of the colonic epithelium. However, 630Δ is more sensitive to ambient oxygen than 630Δ, which coincides with alterations in expression of a variety of -dependent and -independent genes. Finally, we show that 630Δ and 630Δ do not differ in their ability to infect and cause disease in a well-established murine model of CDI. Together, these data support the hypothesis that the mutation in 630Δ arose as a result of exposure to ambient oxygen and that the mutation in 630Δ is unlikely to impact CDI-relevant phenotypes in laboratory studies.
艰难梭菌感染（CDI）以结肠炎和腹泻为特征，每年在美国折磨约50万人，给个人和医疗系统都带来负担。630Δ是临床分离株630的红霉素敏感变体，因其遗传易处理性而在研究界常用。630Δ在PerR（一种调节氧化应激抗性基因的自动调节转录阻遏物）中存在一个点突变。这个点突变导致630Δ中PerR操纵子持续去抑制。为了研究PerR对与耐氧性相关以及与CDI小鼠模型相关的表型的影响，我们校正了点突变体以恢复630Δ中的PerR功能（在此称为630Δ*）。我们证明，在厌氧条件下或暴露于模拟结肠上皮表面附近浓度的氧气时，630Δ和630Δ的生长没有差异。然而，630Δ比630Δ对环境氧更敏感，这与多种PerR依赖性和非依赖性基因表达的改变一致。最后，我们表明，在一个成熟的CDI小鼠模型中，630Δ和630Δ*在感染和致病能力上没有差异。总之，这些数据支持以下假设：630Δ中的PerR突变是由于暴露于环境氧而产生的，并且630Δ中的PerR突变在实验室研究中不太可能影响与CDI相关的表型。
