School of Pharmacy, Sungkyunkwan University, Suwon, 440-746, Republic of Korea.
J Microbiol. 2010 Apr;48(2):229-35. doi: 10.1007/s12275-010-9300-0. Epub 2010 May 1.
ClpP protease is essential for virulence and survival under stress conditions in several pathogenic bacteria. The clpP mutation in a murine infection model has demonstrated both attenuation of virulence and a sensitivity to hydrogen peroxide. However, the underlying mechanisms for these changes have not been resolved. Because macrophages play a major role in immune response and activated macrophages can kill microbes via oxygen-dependant mechanisms, we investigated the effect of the clpP mutation on its sensitivity to macrophage-mediated oxygen-dependant mechanisms. The clpP mutant derived from D39 (serotype 2) exhibited a higher sensitivity to oxidative stresses such as reactive oxygen intermediates, reactive nitrogen intermediates, and H(2)O(2), but no sensitivity to osmotic stress (NaCl) and pH. Moreover, viability of the clpP mutant was significantly increased in murine macrophage cells by treatment with S-methylisothiourea sulfate, which inhibits inducible nitric oxide synthase (iNOS) activity and subsequently elicits lower level secretions of nitric oxide (NO). However, viability of wild type was unchanged. Taken together, these results indicate that ClpP is involved in the resistance to oxidative stresses after entrapment by macrophages and subsequently contributes to virulence via NO mediated pathway.
ClpP 蛋白酶对于几种致病性细菌在应激条件下的毒力和存活至关重要。在鼠感染模型中 clpP 突变既减弱了毒力又增加了对过氧化氢的敏感性。然而，这些变化的潜在机制尚未解决。由于巨噬细胞在免疫反应中起主要作用，并且激活的巨噬细胞可以通过依赖于氧的机制杀死微生物，因此我们研究了 clpP 突变对其对巨噬细胞介导的依赖于氧的机制的敏感性的影响。源自 D39（血清型 2）的 clpP 突变体对氧化应激（如活性氧中间体、活性氮中间体和 H2O2）更敏感，但对渗透压应激（NaCl）和 pH 不敏感。此外，用 S-甲基异硫脲硫酸盐处理可显著增加鼠巨噬细胞中 clpP 突变体的活力，该化合物抑制诱导型一氧化氮合酶（iNOS）的活性，随后引发较低水平的一氧化氮（NO）分泌。然而，野生型的活力没有变化。总之，这些结果表明，ClpP 参与了被巨噬细胞捕获后对氧化应激的抵抗，并且通过 NO 介导的途径有助于毒力。
