Anderson Kelsi L, Roux Christelle M, Olson Matthew W, Luong Thanh T, Lee Chia Y, Olson Robert, Dunman Paul M
Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.
FEMS Immunol Med Microbiol. 2010 Dec;60(3):208-50. doi: 10.1111/j.1574-695X.2010.00736.x. Epub 2010 Oct 6.
Staphylococcus aureus pathogenesis can be attributed partially to its ability to adapt to otherwise deleterious host-associated stresses. Here, Affymetrix GeneChips® were used to examine the S. aureus responses to inorganic acid and alkaline shock and to assess whether stress-dependent changes in mRNA turnover are likely to facilitate the organism's ability to tolerate a pH challenge. The results indicate that S. aureus adapts to pH shock by eliciting responses expected of cells coping with pH alteration, including neutralizing cellular pH, DNA repair, amino acid biosynthesis, and virulence factor expression. Further, the S. aureus response to alkaline conditions is strikingly similar to that of stringent response-induced cells. Indeed, we show that alkaline shock stimulates the accumulation of the stringent response activator (p)ppGpp. The results also revealed that pH shock significantly alters the mRNA properties of the cell. A comparison of the mRNA degradation properties of transcripts whose titers either increased or decreased in response to a sudden pH change revealed that alterations in mRNA degradation may, in part, account for the changes in the mRNA levels of factors predicted to mediate pH tolerance. A set of small stable RNA molecules were induced in response to acid- or alkaline-shock conditions and may mediate adaptation to pH stress.
金黄色葡萄球菌的致病机制部分可归因于其适应宿主相关有害应激的能力。在此，利用Affymetrix基因芯片来检测金黄色葡萄球菌对无机酸和碱性冲击的反应，并评估mRNA周转中依赖应激的变化是否可能促进该生物体耐受pH挑战的能力。结果表明，金黄色葡萄球菌通过引发应对pH改变的细胞预期反应来适应pH冲击，包括中和细胞内pH、DNA修复、氨基酸生物合成和毒力因子表达。此外，金黄色葡萄球菌对碱性条件的反应与严格反应诱导细胞的反应惊人地相似。事实上，我们表明碱性冲击会刺激严格反应激活剂（p）ppGpp的积累。结果还显示，pH冲击会显著改变细胞的mRNA特性。对因突然pH变化而滴度增加或降低的转录本的mRNA降解特性进行比较发现，mRNA降解的改变可能部分解释了预测介导pH耐受性的因子的mRNA水平变化。一组小的稳定RNA分子在酸或碱性冲击条件下被诱导产生，并可能介导对pH应激的适应。
