Bourret Robert B
Department of Microbiology & Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
J Bacteriol. 2017 Aug 22;199(18). doi: 10.1128/JB.00420-17. Print 2017 Sep 15.
Many two-component regulatory systems, including PhoRB, are positively autoregulated, so stimuli result in an increase in the concentration of signaling proteins. When the quantity of signaling proteins depends on exposure history, how do past conditions affect future responses to stimuli? Hoffer et al. (J. Bacteriol. 183:4914-4917, 2001, https://doi.org/doi:10.1128/JB.183.16.4914-4917.2001) previously reported that bacteria "learn" from phosphate starvation and respond more rapidly to subsequent episodes of starvation. Gao et al. (J. Bacteriol. 199:e00390-17, 2017, https://doi.org/doi:10.1128/JB.00390-17) describe another aspect of hysteresis in the PhoRB regulon. Phosphate starvation also leads to a global decline in transcription, counteracting the effects of positive autoregulation and resulting in a similar net response (homeostasis), regardless of exposure history.
许多双组分调节系统，包括PhoRB，都存在正自调节，因此刺激会导致信号蛋白浓度增加。当信号蛋白的数量取决于暴露历史时，过去的条件如何影响未来对刺激的反应？霍弗等人（《细菌学杂志》183:4914 - 4917，2001年，https://doi.org/doi:10.1128/JB.183.16.4914 - 4917.2001）此前报道，细菌从磷酸盐饥饿中“学习”，并对随后的饥饿事件做出更快的反应。高等人（《细菌学杂志》199:e00390 - 17，2017年，https://doi.org/doi:10.1128/JB.00390 - 17）描述了PhoRB调节子中滞后现象的另一个方面。磷酸盐饥饿还会导致转录全面下降，抵消正自调节的作用，并导致类似的净反应（稳态），而与暴露历史无关。
