Bacteria spend their lives buffeted by changing environmental conditions. To adapt to and survive these stresses, bacteria have global response systems that result in sweeping changes in gene expression and cellular metabolism. These responses are controlled by master regulators, which include: alternative sigma factors, such as RpoS and RpoH; small molecule effectors, such as ppGpp; gene repressors such as LexA; and, inorganic molecules, such as polyphosphate. The response pathways extensively overlap and are induced to various extents by the same environmental stresses. These stresses include nutritional deprivation, DNA damage, temperature shift, and exposure to antibiotics. All of these global stress responses include functions that can increase genetic variability. In particular, up-regulation and activation of error-prone DNA polymerases, down-regulation of error-correcting enzymes, and movement of mobile genetic elements are common features of several stress responses. The result is that under a variety of stressful conditions, bacteria are induced for genetic change. This transient mutator state may be important for adaptive evolution.

中文翻译：

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细菌中的应激诱导诱变。

细菌终其一生都在不断变化的环境条件中度过。为了适应和生存这些压力，细菌具有全球反应系统，导致基因表达和细胞代谢发生彻底变化。这些响应由主调节器控制，其中包括： 替代西格玛因子，例如 RpoS 和 RpoH；小分子效应物，如ppGpp；基因阻遏物，如 LexA；和无机分子，如聚磷酸盐。响应途径广泛重叠，并在不同程度上受到相同环境压力的影响。这些压力包括营养剥夺、DNA 损伤、温度变化和接触抗生素。所有这些全球压力反应都包括可以增加遗传变异性的功能。特别是容易出错的 DNA 聚合酶的上调和激活，错误纠正酶的下调和可移动遗传元件的运动是几种应激反应的共同特征。结果是，在各种压力条件下，细菌被诱导进行基因改变。这种瞬态突变状态可能对适应性进化很重要。