RUI: pH Regulation of Genes in Escherichia coli

对pH变化的遗传反应将在大肠杆菌中进行研究。外部pH值是细菌的主要环境参数，内部pH值在细菌生理和能量转导方面具有重要意义。两个新的pH调节位点，作为lacZ操纵子融合体，将被研究：一个是由膜渗透性弱酸和质子载体诱导的，另一个是由外部碱诱导的。将对这些基因座进行克隆和测序，并对其序列进行启动子和调控位点分析。酸敏感序列如H-DNA可能的调控作用将被研究。我们将在体外测试ina转录的pH依赖性。通过筛选组成型或不可诱导型的Tn10分离株，分离出ina和alx的调节基因。将寻找表现出pH稳态缺陷的突变体。

The genetic response to pH change will be investigated in Escherichia coli. External pH is a major environmental parameter for bacteria, and internal pH is significant in terms of bacterial physiology and energy transduction. Two novel pH- regulated loci, isolated as lacZ operon fusions, will be studied: ina inducible by membrane-permeable weak acids and protonophores, and alx inducible by external base. These loci will be cloned and sequenced, and their sequences analyzed for promoters and regulatory sites. The possible regulatory role of acid-sensitive sequences such as H-DNA will be investigated. The pH dependence of ina transcription will be tested in vitro. Regulator genes for ina and alx will be isolated, by screening Tn10 pools for isolates which are either constitutive or uninducible. Mutants exhibiting defective pH homeostasis will be sought.