Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, the Netherlands.
Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, the Netherlands.
Mol Microbiol. 2024 Oct;122(4):413-428. doi: 10.1111/mmi.15300. Epub 2024 Jul 30.
To survive in the host, pathogenic bacteria need to be able to react to the unfavorable conditions that they encounter, like low pH, elevated temperatures, antimicrobial peptides and many more. These conditions may lead to unfolding of envelope proteins and this may be lethal. One of the mechanisms through which bacteria are able to survive these conditions is through the protease/foldase activity of the high temperature requirement A (HtrA) protein. The gut pathogen Clostridioides difficile encodes one HtrA homolog that is predicted to contain a membrane anchor and a single PDZ domain. The function of HtrA in C. difficile is hitherto unknown but previous work has shown that an insertional mutant of htrA displayed elevated toxin levels, less sporulation and decreased binding to target cells. Here, we show that HtrA is membrane associated and localized on the surface of C. difficile and characterize the requirements for proteolytic activity of recombinant soluble HtrA. In addition, we show that the level of HtrA in the bacteria heavily depends on its proteolytic activity. Finally, we show that proteolytic activity of HtrA is required for survival under acidic conditions.
为了在宿主中存活，致病菌需要能够对其遇到的不利条件（如低 pH 值、高温、抗菌肽等）做出反应。这些条件可能导致包膜蛋白的展开，这可能是致命的。细菌能够在这些条件下存活的一种机制是通过高温需求 A (HtrA) 蛋白的蛋白酶/折叠酶活性。肠道病原体艰难梭菌编码一种 HtrA 同源物，预测该同源物含有一个膜锚和一个 PDZ 结构域。HtrA 在艰难梭菌中的功能尚不清楚，但以前的工作表明，htrA 的插入突变体显示出毒素水平升高、孢子形成减少和与靶细胞结合减少。在这里，我们表明 HtrA 与膜相关，并定位于艰难梭菌的表面，并对重组可溶性 HtrA 的蛋白水解活性的要求进行了表征。此外，我们表明 HtrA 在细菌中的水平严重依赖于其蛋白水解活性。最后，我们表明 HtrA 的蛋白水解活性对于在酸性条件下的生存是必需的。
