Foster J W, Hall H K
Department of Microbiology and Immunology, College of Medicine, University of South Alabama, Mobile 36688.
J Bacteriol. 1991 Aug;173(16):5129-35. doi: 10.1128/jb.173.16.5129-5135.1991.
The acid tolerance response (ATR) is an adaptive system triggered at external pH (pHo) values of 5.5 to 6.0 that will protect cells from more severe acid stress (J. Foster and H. Hall, J. Bacteriol. 172:771-778, 1990). Correlations between the internal pH (pHi) of adapted versus unadapted cells at pHo of 3.3 indicate that the ATR system produces an inducible pH-homeostatic function. This function serves to maintain the pHi above 5 to 5.5. Below this range, cells rapidly lose viability. Development of this pH homeostasis mechanism was sensitive to protein synthesis inhibitors and operated only to augment the pHi at pHo values below 4. In contrast, classical constitutive pH homeostasis was insensitive to protein synthesis inhibitors and was efficient only at pHo values above 4. Physiological studies indicated an important role for the Mg(2+)-dependent proton-translocating ATPase in affording ATR-associated survival during exposure to severe acid challenges. Along with being acid intolerant, cells deficient in this ATPase did not exhibit inducible pH homeostasis. We speculate that adaptive acid tolerance is important to Salmonella species in surviving acid encounters in both the environment and the infected host.
耐酸应答（ATR）是一种适应性系统，在外部pH（pHo）值为5.5至6.0时触发，可保护细胞免受更严重的酸胁迫（J.福斯特和H.霍尔，《细菌学杂志》172:771 - 778，1990年）。在pHo为3.3时，适应型细胞与未适应型细胞的内部pH（pHi）之间的相关性表明，ATR系统产生一种可诱导的pH稳态功能。该功能用于将pHi维持在5至5.5以上。低于此范围，细胞会迅速丧失活力。这种pH稳态机制的发展对蛋白质合成抑制剂敏感，且仅在pHo值低于4时起作用以提高pHi。相比之下，经典的组成型pH稳态对蛋白质合成抑制剂不敏感，且仅在pHo值高于4时有效。生理学研究表明，Mg(2 +)依赖性质子转运ATP酶在暴露于严重酸挑战期间提供与ATR相关的存活中起重要作用。除了不耐酸外，缺乏这种ATP酶的细胞也不表现出可诱导的pH稳态。我们推测，适应性耐酸对沙门氏菌在环境和受感染宿主中遭遇酸时的存活很重要。
